Sodium hydroxide production with carboxylic acid and sulfur dioxide intermediates

BACKGROUND AND SUMMARY

Sodium hydroxide is generally produced using the chlor-alkali process, which is energy intensive, requires rare metal anodes and cathodes, and produces hydrochloric acid, which has a limited market and cannot be discharged into the environment. Production of sodium hydroxide in prior art is energy intensive, CO₂emissions intensive, and expensive. Additionally, prior art production of sodium hydroxide may not be employed in CO₂removal, or may not be added to a sea for deacidification or CO₂removal, because they are energy intensive, CO₂emissions intensive, expensive, and environmentally damaging. Commercial applications of hydrochloric acid often involve employing hydrochloric acid in a reaction with a carbonate salt, which may result in the release of CO₂and may counter any CO₂emissions reduction benefit. Additionally, if hydrochloric acid is released into the environment, it will react with carbonate or bicarbonate salts present in the environment, emitting carbon dioxide and acidifying water bodies, such as the ocean. Sodium hydroxide is an essential chemical employed in a wide range of applications, which include, for example, pulp & paper production, lithium processing, soap production, rayon production, aluminum refining, to name a few. Production of sodium hydroxide in prior art is energy intensive, CO₂emissions intensive, and expensive. Reducing the energy, cost, and emissions associated with the production of sodium hydroxide would greatly benefit the economy and environment. There is a significant need for a low energy consumption, low CO₂emissions, environmentally friendly process for producing sodium hydroxide.

Production of calcium oxide, or calcium hydroxide, or cement klinker in prior art produces CO₂emissions, which may be difficult or expensive to capture. It may be highly desirable to develop a calcium oxide, or calcium hydroxide, or cement klinker production process which does not produce CO₂emissions and/or inherently produces high purity, captured CO₂.

Some embodiments of the present invention may pertain to low carbon emissions, or low energy consumption, or carbon negative production of sodium hydroxide, or sodium carbonate, or sodium bicarbonate, or sodium sulfite, or sodium bisulfite, or gypsum, or alkaline-earth sulfate, or alkali hydroxide, or alkali carbonate, or alkali bicarbonate, or alkali sulfite. Some embodiments of the present invention may enable ultra-low CO₂emissions production of sodium hydroxide with calcium sulfate as the side product. Calcium sulfate comprises a solid, is minimally soluble in water, is non-toxic, is not dangerous for the environment, and has a multi-billion metric ton per year market in gypsum wallboard, concrete aggregates, fireproofing, plaster, building materials, and other applications. Some embodiments of the present invention may be capable of scaling to greater than 1 billion ton per year CO₂emissions reduction, or carbon removal, or a combination thereof. Some embodiments of the present invention may enable highly scalable, environmentally beneficial systems and methods for ocean deacidification, which are capable of scaling to meaningfully increase ocean pH, rejuvenate marine ecosystems, and permanently sequester carbon dioxide. Additionally some embodiments may lower the required cost and energy consumption of alkali hydroxides, alkali carbonates, and alkali bicarbonates. Some embodiments may be employ equipment comprising abundant and recyclable materials.

Some embodiments of the present invention may pertain to low carbon emissions, or low energy consumption, or carbon negative production of calcium oxide, or calcium hydroxide, or calcium carbonate, or magnesium oxide, or magnesium hydroxide, or cement, or cement klinker, or Portland cement, or magnesium carbonate, or alkaline earth oxide, or alkaline earth hydroxide, or alkaline earth carbonate or any combination thereof. Some embodiments of the present invention may enable ultra-low CO₂emissions production of calcium oxide, or magnesium oxide, or cement. Some embodiments may comprise a CO₂capture process, or a CO₂air capture process, or CO₂removal process, or a CO₂conversion process, or a CO₂separation process, or a process for recovering or separating CO₂from solutions comprising carbonate, or bicarbonate, or any combination thereof. Some embodiments of the present invention may enable calcium oxide or cement production with inherent production of high purity, high pressure carbon dioxide in the nature of the process, which may reduce the cost and energy required to produce low emissions or zero emissions calcium oxide or cement. Some embodiments may be employ equipment comprising abundant and recyclable materials.

Advantages of some embodiments include lower energy consumption, lower cost, or lower CO₂emissions, CO₂emissions negative outputs, or application in carbon dioxide removal, or no strong acid products, or abundant materials, or global scalability.

BRIEF FIGURE DESCRIPTIONS

FIG. 1: Process for producing calcium oxide and captured carbon dioxide with carboxylic acid and sulfur dioxide intermediates.

FIG. 2A: Process for producing calcium oxide and weak acid derivative employing carboxylic acid and sulfur dioxide intermediates.

FIG. 2B: Process for producing calcium oxide and weak acid derivative employing carboxylic acid and sulfur dioxide intermediates.

FIG. 3A: Process for producing magnesium oxide and weak acid derivative employing carboxylic acid and sulfur dioxide intermediates.

FIG. 3B: Process for producing magnesium oxide and weak acid derivative employing carboxylic acid and sulfur dioxide intermediates.

FIG. 4A: Process for producing alkaline earth oxide and captured carbon dioxide employing carboxylic acid, alkali, and sulfur dioxide intermediates.

FIG. 4B: Process for producing alkaline earth oxide and captured carbon dioxide employing carboxylic acid, alkali, and sulfur dioxide intermediates.

FIG. 4C: Process for producing alkaline earth oxide and captured carbon dioxide employing carboxylic acid, alkali, and sulfur dioxide intermediates.

FIG. 5A: Process for producing alkaline earth oxide and weak acid derivative employing carboxylic acid, alkali, and sulfur dioxide intermediates.

FIG. 5B: Process for producing alkaline earth oxide and weak acid derivative employing carboxylic acid, alkali, and sulfur dioxide intermediates.

FIG. 5C: Process for producing alkaline earth oxide and weak acid derivative employing carboxylic acid, alkali, and sulfur dioxide intermediates.

FIG. 5D: Process for producing alkaline earth oxide and weak acid derivative employing carboxylic acid, alkali, and sulfur dioxide intermediates.

FIG. 5E: Process for producing alkaline earth oxide and weak acid derivative employing carboxylic acid, alkali, and sulfur dioxide intermediates.

FIG. 5F: Process for producing alkaline earth oxide and weak acid derivative employing carboxylic acid, alkali, and sulfur dioxide intermediates.

FIG. 6A: Process for producing alkaline earth oxide and weak acid derivative employing carboxylic acid, alkali, and sulfur dioxide intermediates.

FIG. 6B: Process for producing alkaline earth oxide and weak acid derivative employing carboxylic acid, alkali, and sulfur dioxide intermediates.

FIG. 7A: Process for producing alkaline earth oxide and weak acid derivative employing carboxylic acid, alkali, and sulfur dioxide intermediates with membrane separation of at least a portion of alkali sulfite.

FIG. 7B: Process for producing alkaline earth oxide and weak acid derivative employing carboxylic acid, alkali, and sulfur dioxide intermediates with membrane separation of at least a portion of alkali sulfite.

FIG. 8: Process for producing alkaline earth oxide and weak acid derivative employing carboxylic acid, alkali, and sulfur dioxide intermediates with membrane separation of at least a portion of alkali sulfite.

FIG. 9A: Process for producing alkali hydroxide from alkali sulfate using carboxylic acid and sulfur dioxide intermediates.

FIG. 9B: Process for producing alkali hydroxide from alkali sulfate using carboxylic acid and sulfur dioxide intermediates.

FIG. 9C: Process for producing alkali hydroxide from alkali sulfate using carboxylic acid and sulfur dioxide intermediates.

FIG. 9D: Process for producing alkali hydroxide from alkali sulfate using carboxylic acid and sulfur dioxide intermediates.

FIG. 10A: Process for producing alkali hydroxide from alkali sulfate using carboxylic acid and sulfur dioxide intermediates.

FIG. 10B: Process for producing alkali hydroxide from alkali sulfate using carboxylic acid and sulfur dioxide intermediates.

FIG. 10C: Process for producing alkali hydroxide from alkali sulfate using carboxylic acid and sulfur dioxide intermediates.

FIG. 10D: Process for producing alkali hydroxide from alkali sulfate using carboxylic acid and sulfur dioxide intermediates.

FIG. 10E: Process for producing alkali hydroxide from alkali sulfate using carboxylic acid and sulfur dioxide intermediates.

FIG. 10F: Process for producing alkali hydroxide from alkali sulfate using carboxylic acid and sulfur dioxide intermediates.

FIG. 11A: Process for producing alkali hydroxide from alkali sulfate using carboxylic acid and sulfur dioxide intermediates.

FIG. 11B: Process for producing alkali hydroxide from alkali sulfate using carboxylic acid and sulfur dioxide intermediates.

FIG. 11C: Process for producing alkali hydroxide from alkali sulfate using carboxylic acid and sulfur dioxide intermediates.

FIG. 12A: Process for producing alkali hydroxide from alkali sulfate using carboxylic acid and sulfur dioxide intermediates.

FIG. 12B: Process for producing alkali hydroxide from alkali sulfate using carboxylic acid and sulfur dioxide intermediates.

FIG. 12C: Process for producing alkali hydroxide from alkali sulfate using carboxylic acid and sulfur dioxide intermediates.

FIG. 13A: Process for producing alkali carbonate and removing or capturing or converting CO₂from alkali sulfate employing acid, such as carboxylic acid, and sulfur dioxide intermediates.

FIG. 13B: Process for producing alkali carbonate and removing or capturing or converting CO₂from alkali sulfate employing acid, such as carboxylic acid, and sulfur dioxide intermediates.

FIG. 13C: Process for producing alkali carbonate and removing or capturing or converting CO₂from alkali sulfate employing acid, such as carboxylic acid, and sulfur dioxide intermediates.

FIG. 13D: Process for producing alkali carbonate and removing or capturing or converting CO₂from alkali sulfate employing acid, such as carboxylic acid, and sulfur dioxide intermediates.

FIG. 13E: Process for producing alkali carbonate and removing or capturing or converting CO₂from alkali sulfate employing acid, such as carboxylic acid, and sulfur dioxide intermediates.

FIG. 13F: Process for producing alkali carbonate and removing or capturing or converting CO₂from alkali sulfate employing acid, such as carboxylic acid, and sulfur dioxide intermediates.

FIG. 14A: Process for producing alkali carbonate and removing or capturing or converting CO₂from alkali sulfate employing carboxylic acid and sulfur dioxide intermediates.

FIG. 14B: Process for producing alkali carbonate and removing or capturing or converting CO₂from alkali sulfate employing carboxylic acid and sulfur dioxide intermediates.

FIG. 14C: Process for producing alkali carbonate and removing or capturing or converting CO₂from alkali sulfate employing carboxylic acid and sulfur dioxide intermediates.

FIG. 15A: Process for producing alkaline earth oxide and weak acid derivative employing carboxylic acid, alkali (such as ammonia or ammonium), and sulfur dioxide intermediates.

FIG. 15B: Process for producing alkaline earth oxide and weak acid derivative employing carboxylic acid, alkali (such as ammonia or ammonium), and sulfur dioxide intermediates.

FIG. 15C: Process for producing alkaline earth oxide and weak acid derivative employing carboxylic acid, alkali (such as ammonia or ammonium), and sulfur dioxide intermediates.

FIG. 16A: Process for producing alkaline earth oxide and weak acid derivative employing carboxylic acid, alkali (such as ammonia or ammonium), and sulfur dioxide intermediates.

FIG. 16B: Process for producing alkaline earth oxide and weak acid derivative employing carboxylic acid, alkali (such as ammonia or ammonium), and sulfur dioxide intermediates.

FIG. 16C: Process for producing alkaline earth oxide and weak acid derivative employing carboxylic acid, alkali (such as ammonia or ammonium), and sulfur dioxide intermediates.

FIG. 17A: Process for producing alkaline earth oxide and weak acid derivative employing carboxylic acid, alkali (such as ammonia or ammonium), and sulfur dioxide intermediates.

FIG. 17B: Process for producing alkaline earth oxide and weak acid derivative employing carboxylic acid, alkali (such as ammonia or ammonium), and sulfur dioxide intermediates.

FIG. 17C: Process for producing alkaline earth oxide and weak acid derivative employing carboxylic acid, alkali (such as ammonia or ammonium), and sulfur dioxide intermediates.

FIG. 18: Process for producing alkaline earth oxide and weak acid derivative employing carboxylic acid, alkali (such as ammonia or ammonium), and sulfur dioxide intermediates.

FIG. 19: Process for producing alkaline earth oxide and weak acid derivative employing carboxylic acid, alkali (such as ammonia or ammonium), and sulfur dioxide intermediates.

FIG. 20A: Process for producing or recovering ammonia from ammonium sulfate

FIG. 20B: Process for producing or recovering ammonia from ammonium sulfate

FIG. 20C: Process for producing or recovering ammonia from ammonium sulfate

FIG. 21A: Process for producing or recovering ammonia from ammonium sulfate

FIG. 21B: Process for producing or recovering ammonia from ammonium sulfate

FIG. 21C: Process for producing or recovering ammonia from ammonium sulfate

FIG. 22A: Process for producing or recovering ammonia from ammonium sulfate

FIG. 22B: Process for producing or recovering ammonia from ammonium sulfate

FIG. 22C: Process for producing or recovering ammonia from ammonium sulfate

FIG. 23A: Process for producing or recovering ammonia from ammonium sulfate

FIG. 23B: Process for producing or recovering ammonia from ammonium sulfate

FIG. 23C: Process for producing or recovering ammonia from ammonium sulfate

FIG. 24: Process for thermally decomposing or calcining alkaline earth sulfite to form alkaline earth oxide and sulfur dioxide and/or absorbing sulfur dioxide employing a recirculating carrier gas to, for example, enable use of zero emissions heat and/or enable low diatomic oxygen concentrations

FIG. 25: Process for thermally decomposing or calcining alkaline earth sulfite to form alkaline earth oxide and sulfur dioxide and/or absorbing sulfur dioxide employing a recirculating carrier gas

FIG. 26A: Process for producing alkali hydroxide using carboxylic acid and sulfur dioxide intermediates from alkali chloride.

FIG. 26B: Process for producing alkali hydroxide using carboxylic acid and sulfur dioxide intermediates from alkali chloride.

FIG. 26C: Process for producing alkali hydroxide using carboxylic acid and sulfur dioxide intermediates from alkali chloride.

FIG. 26D: Process for producing alkali hydroxide using carboxylic acid and sulfur dioxide intermediates from alkali chloride.

FIG. 27: Process for producing alkali sulfate from alkali chloride and alkaline earth sulfate using ammonia and carbon dioxide intermediates

FIG. 28A: Process for producing alkali sulfate from alkali chloride and alkaline earth sulfate using ammonia and carbon dioxide intermediates

FIG. 28B: Process for producing alkali sulfate from alkali chloride and alkaline earth sulfate using ammonia and carbon dioxide intermediates

FIG. 28C: Process for producing alkali sulfate from alkali chloride and alkaline earth sulfate using ammonia and carbon dioxide intermediates

FIG. 29: Process for producing alkali sulfate and capturing CO₂employing alkali chloride and alkaline earth sulfate using ammonia and carbon dioxide intermediates

FIG. 30: Process for producing alkali sulfate, capturing CO₂, and/or producing urea employing alkali chloride and alkaline earth sulfate using ammonia and carbon dioxide

FIG. 31A: Process for producing alkali hydroxide from alkali sulfite employing acid and sulfur dioxide intermediates

FIG. 31B: Process for producing alkali hydroxide from alkali sulfite employing acid and sulfur dioxide intermediates

FIG. 31C: Process for producing alkali hydroxide from alkali sulfite employing acid and sulfur dioxide intermediates

FIG. 32A: Process for absorbing or reacting sulfur dioxide within alkali acid-anion, such as alkali carboxylate, in a manner which may minimize or reduce potential residual vapor in remaining gases.

FIG. 32B: Process for absorbing or reacting sulfur dioxide within alkali acid-anion, such as alkali carboxylate, in a manner which may minimize or reduce potential residual vapor in remaining gases.

FIG. 33: Process for producing alkali hydroxide from alkali sulfate using carboxylic acid and sulfur dioxide intermediates.

FIG. 34: Process for producing alkali hydroxide from alkali sulfate using carboxylic acid, sulfur dioxide, and carbon dioxide intermediates.

FIG. 35: Process for producing alkali hydroxide from alkali sulfate using carboxylic acid, sulfur dioxide, and carbon dioxide intermediates.

FIG. 36A: Process for producing alkali bicarbonate or carbonate from alkali sulfate using carboxylic acid and sulfur dioxide intermediates and carbon dioxide input and intermediate.

FIG. 36B: Process for producing alkali bicarbonate or carbonate from alkali sulfate using carboxylic acid and sulfur dioxide intermediates and carbon dioxide input and intermediate.

FIG. 37: Process for producing alkali hydroxide from alkali sulfate using carboxylic acid, magnesium, sulfur dioxide, and carbon dioxide intermediates.

FIG. 38: Process for producing alkali hydroxide from alkali sulfate using carboxylic acid, magnesium, sulfur dioxide, and carbon dioxide intermediates.

FIG. 39A: Process for producing alkali bicarbonate or carbonate from alkali sulfate using carboxylic acid and sulfur dioxide intermediates and carbon dioxide input and intermediate.

FIG. 39B: Process for producing alkali bicarbonate or carbonate from alkali sulfate using carboxylic acid and sulfur dioxide intermediates and carbon dioxide input and intermediate.

DETAILED DESCRIPTION
Example Chemistry
Example 1: Process for Producing Calcium Oxide or Cement or Clinker

(1) React Material comprising Calcium, or Magnesium, or Other Alkaline Earth-Weak Acid Anion with Acetic Acid, which may comprise, including, but not limited to, one or more or any combination of the following:

CaCO₃(s or aq)+2CH₃COOH(aq) custom character Ca(CH₃COO)₂(aq)+CO₂(g)
Calcium Silicate(s)+2CH₃COOH(aq)Ca(CH₃COO)₂(aq)+Silicon Dioxide(s)
CaS(s)+2CH₃COOH(aq)Ca(CH₃COO)₂(aq)+H₂S(g)
Calcium(Weak Acid Anion)+2CH₃COOH(aq)Ca(CH₃COO)₂(aq)+Weak Acid(s, or g, or l, or aq)

Note: Residual solids or undissolved solids, such as silicon dioxide or other undissolved solids, may be separated from the liquid solution using a solid-liquid separation.

Note: CO₂(g) may comprise captured CO₂.

Note: In some embodiments, acetic acid vapor and/or water vapor may be separated or recovered from CO₂(g).

Ca(CH₃COO)₂(aq)+SO₂(g or aq)+H₂O(l or aq) custom character CaSO₃(s)+2CH₃COOH(aq) (2)

Note: CaSO₃(s) may be separated using a solid-liquid separation.

Note: In some embodiments, SO₂(g) may comprise other gases in addition to SO₂(g). In some embodiments, the remaining gases after the absorption or reaction of at least a portion of SO₂(g) may comprise a portion of acetic acid vapor. In some embodiments, the remaining gases after the absorption or reaction of at least a portion of SO₂(g) may comprise at least a portion of acetic acid vapor, which may comprise acetic acid evaporated from the products of reaction step ‘(2)’. In some embodiments, remaining gases comprising at least a portion of acetic acid vapor may be contacted with Ca(CH₃COO)₂(aq) before the reaction with SO₂(g), which may enable at least a portion of acetic acid vapor to be absorbed in the Ca(CH₃COO)₂(aq) and/or removed from the remaining gases. In some embodiments, acetic acid vapor may be removed from remaining gases using, for example, including, but not limited to, one or more or any combination of the following: alkaline earth carbonate, or alkaline earth-weak acid, or alkaline earth carbonate-water slurry, or alkaline earth oxide, or alkaline earth hydroxide, or alkaline earth hydroxide-water slurry, or alkaline earth hydroxide-water suspension, or alkaline earth hydroxide-water solution, or water, or alkali carbonate, or alkali bicarbonate, or alkali hydroxide.

Note: In some embodiments, residual aqueous magnesium sulfite may be present in the ‘2CH₃COOH(aq)’. In some embodiments, the residual aqueous magnesium sulfite may remain in the ‘2CH₃COOH(aq)’ transferred to reaction ‘(1)’ from, for example, reaction ‘(2)’. In some embodiments, at least a portion of the aqueous magnesium sulfite may remain in the ‘2CH₃COOH(aq)’ solution transferred to reaction ‘(1)’ from reaction ‘(2)’/. Additional magnesium sulfite above the solubility limits of magnesium sulfite in the solution may precipitate or co-precipitate during the reaction of Ca(CH₃COO)₂(aq) or Mg(CH₃COO)₂(aq) with SO₂(g or aq), or sulfite, or bisulfite, or any combination thereof.

Note: In some embodiments, residual aqueous magnesium sulfite may be present in the ‘2CH₃COOH(aq)’. In some embodiments, a portion of the residual aqueous magnesium sulfite may be concentrated and/or separated using, including, but not limited to, one or more, or any combination of the following: heating, or cooling, or reverse osmosis, or membrane based process, or precipitation, or electrodialysis, or forward osmosis, or any combination thereof. For example, the residual aqueous magnesium sulfite may be separated by concentrating the magnesium sulfite using reverse osmosis or nanofiltration, wherein the pore size or properties of the membrane may enable the permeation of at least a portion of the acetic acid and the rejection of at least a portion of magnesium sulfite, and/or cooling the resulting concentrated magnesium sulfite solution to produce at least a portion of a magnesium sulfite precipitate.

CaSO₃(s) custom character CaO(s)+SO₂(g) (3)

Note: ‘(3)’ may comprise calcining CaSO₃(s), which may employ a kiln.

Note: CaSO₃(s) may be dried, or dehydrated, or both before or during ‘(3)’.

Example 2: Process for Producing Magnesium Oxide or Cement or Clinker

(1) React Material comprising Calcium, or Magnesium, or Other Alkaline Earth-Weak Acid Anion with Acetic Acid

MgCO₃(s or aq)+2CH₃COOH(aq) custom character Mg(CH₃COO)₂(aq)+CO₂(g)
Magnesium Silicate(s)+2CH₃COOH(aq)Mg(CH₃COO)₂(aq)+Silicon Dioxide(s)
MgS(s)+2CH₃COOH(aq)Mg(CH₃COO)₂(aq)+H₂S(g)
Magnesium(Weak Acid Anion)+2CH₃COOH(aq)Mg(CH₃COO)₂(aq)+Weak Acid(s, or g, or l, or aq)

Note: Residual solids or undissolved solids, such as silicon dioxide or other undissolved solids, may be separated from the liquid solution using a solid-liquid separation.

Note: In some embodiments, 2CH₃COOH(aq) may comprise at least a portion of MgSO₃(aq), which may be referred to as residual MgSO₃(aq).

Mg(CH₃COO)₂(aq)+SO₂(g or aq)+H₂O(l or aq) custom character MgSO₃(s)+2CH₃COOH(aq) (2)

Note: MgSO₃(s) may be separated using a solid-liquid separation.

Note: Residual MgSO₃(aq) may be present in the 2CH₃COOH(aq) solution.

MgSO₃(s) custom character MgO(s)+SO₂(g) (3)

Note: ‘(3)’ may comprise calcining MgSO₃(s), which may employ a kiln.

Note: MgSO₃(s) may be dried, or dehydrated, or both before or during ‘(3)’.

Example 3: Process for Producing Calcium Oxide or Cement or Clinker with Alkali Intermediate

(1) React Material comprising Calcium, or Magnesium, or Other Alkaline Earth-Weak Acid Anion with Acetic Acid

CaCO₃(s or aq)+2CH₃COOH(aq) custom character Ca(CH₃COO)₂(aq)+CO₂(g)
Calcium Silicate(s)+2CH₃COOH(aq)Ca(CH₃COO)₂(aq)+Silicon Dioxide(s)
CaS(s)+2CH₃COOH(aq)Ca(CH₃COO)₂(aq)+H₂S(g)
Calcium(Weak Acid Anion)+2CH₃COOH(aq)Ca(CH₃COO)₂(aq)+Weak Acid(s, or g, or l, or aq)

Note: Residual solids or undissolved solids, such as silicon dioxide or other undissolved solids, may be separated from the liquid solution using a solid-liquid separation.

Note: If CO₂(g) is produced, it may be desirable for said CO₂(g) to be produced at a high partial pressure CO₂(g), or purity CO₂(g), or to comprise captured CO₂(g).

Ca(CH₃COO)₂(aq)+Na₂SO₃(s or aq) custom character 2NaCH₃COO(aq)+CaSO₃(s) (2)

Note: CaSO₃(s) may be separated using a solid-liquid separation.

Note: In some embodiments, Na₂SO₃(s or aq) may comprise a solid comprising sodium sulfite, which may be added to or dissolved in a solution comprising calcium acetate.

Note: In some embodiments, Na₂SO₃(s or aq) may comprising an aqueous solution comprising sodium sulfite and acetic acid.

2NaCH₃COO(aq)+SO₂(g or aq)+H₂O(l or aq) custom character Na₂SO₃(aq)+2CH₃COOH(aq) (3)

Note: In some embodiments, SO₂(g) may comprise other gases in addition to SO₂(g). In some embodiments, the reaction of 2NaCH₃COO(aq)+SO₂(g) may result in at least a portion of acetic acid vapor in the remaining gases during or after the reaction. In some embodiments, NaCH₃COO(aq) entering the present step may be pre-contacted with or may absorb at least a portion of acetic acid vapor from the remaining gases. In some embodiments, the reactor or absorption column may be configured to absorb acetic acid vapor in NaCH₃COO(aq) before or while reacting NaCH₃COO(aq) with SO₂(g). In some embodiments, acetic acid vapor may be removed from remaining gases using, for example, including, but not limited to, one or more or any combination of the following: alkaline earth carbonate, or alkaline earth-weak acid, or alkaline earth carbonate-water slurry, or alkaline earth oxide, or alkaline earth

Na₂SO₃(aq)+2CH₃COOH(aq) custom character 2CH₃COOH(aq or l)+Na₂SO₃(s) (4)

Note: CH₃COOH may be more soluble in water than Na₂SO₃. In some embodiments, Na₂SO₃may be separated or precipitated from solution by, for example, including, but not limited to, evaporation, or distillation, or crystallization, or separation systems or methods described herein, or separation systems or methods described in the art, or any combination thereof.

Note: In some embodiments, CH₃COOH and/or water may be separated from Na₂SO₃by, for example, evaporation, or distillation, or crystallization, or any combination thereof. In some embodiments, CH₃COOH may evaporate with water vapor and/or condense with water vapor, which may result in a distillate or condensate comprising CH₃COOH(aq).

Note: In some embodiments, magnesium sulfite(aq) may be present in the Na₂SO₃(aq)+2CH₃COOH(aq). In some embodiments, if present, magnesium sulfite may begin to precipitate or crystalize before Na₂SO₃. In some embodiments magnesium sulfite solid may be separated during step ‘(4)’. In some embodiments, separated magnesium sulfite may be decomposed to magnesium oxide, or decomposed separately from calcium sulfite, or decomposed together with calcium sulfite, or any combination thereof.s

Note: Na₂SO₃(s) may be separated from CH₃COOH(aq) by a solid-liquid separation, which may include, but is not limited to, filter, or centrifuge, or decanter, or separation systems or methods described herein, or separation systems or methods described in the art, or any combination thereof.

Note: In some embodiments, a feed solution comprising sodium sulfite and acetic acid may be evaporated, wherein a portion of acetic acid and water vapor evaporate and/or are condensed to form an a separated acetic acid solution, and/or the remaining solution comprises aqueous acetic acid and a higher concentration of sodium sulfite than in the concentration of sodium sulfite in the feed solution.

CaSO₃(s) custom character CaO(s)+SO₂(g) (5)

Note: ‘(5)’ may comprise calcining CaSO₃(s), which may employ a kiln.

Note: CaSO₃(s) may be dried, or dehydrated, or both before, or during ‘(5)’.

Note: In some embodiments, it may be preferred or desired to react SO₂(g) with NaCH₃COO(aq) to form Na₂SO₃(aq), and then react Na₂SO₃with Ca(CH₃COO)₂(aq) to form CaSO₃(s) because, for example, including, but not limited to, one or more or any combination of the following potential benefits:

- In some embodiments, it may be desirable to absorb SO₂(g) in an absorption column. Precipitate formation can be problematic in an absorption column due to, for example, including, but not limited to, precipitate clogging packing material, or plates, or interfering with gas flows, or interfering with liquid flows, or forming scaling, or any combination thereof. The reaction of Ca(CH₃COO)₂(aq) with SO₂(g) may form a precipitate comprising CaSO₃(s), which may be challenging in some absorption columns or a gas absorption processes. The reaction of NaCH₃COO(aq) with SO₂(g) may, if desired, the salt may mostly remain at an aqueous or liquid phase throughout the reaction, because, for example, Na₂SO₃may be soluble in water, which may be desirable in an absorption column.
- In some embodiments, if the SO₂(g) comprises gases in addition to SO₂(g), acetic acid vapor may be present in the remaining gases during or after the reaction of SO₂(g) with an acetate salt. If SO₂(g) is contacted with NaCH₃COO(aq), which may form aqueous phase Na₂SO₃(aq) and/or acetic acid, the reactor or absorption column may be configured such that NaCH₃COO(aq) entering the reactor or absorption column absorbs or recovers at least a portion of acetic acid vapor from the remaining gases. If SO₂(g) is contacted with NaCH₃COO(aq), which may form aqueous phase Na₂SO₃(aq) and/or acetic acid, the reactor or absorption column may be configured such that NaCH₃COO(aq) entering the reactor or absorption column absorbs or recovers at least a portion of acetic acid vapor from the remaining gases before or while NaCH₃COO(aq) is substantially reacted with SO₂(g). The employing NaCH₃COO(aq) may react with residual SO₂(g) potentially present in the remaining gases, which may avoid solid formation or solid handing issues which may occur if Ca(CH₃COO)₂(aq) is reacted with residual SO₂(g).
- For example, in some embodiments in some embodiments, the ability for the reaction products to comprise aqueous or pumpable phases may enable absorption column, or absorber, or reactor, or any combination thereof designs or configurations which may facilitate the recovery of acetic acid vapor and/or may reduce the potential amount or concentration of acetic acid vapor in the remaining gases.
- For example, it may be desirable to absorb SO₂(g) in an absorption column because the SO₂(g) may be at a dilute concentration, or a low partial pressure, or may comprise a gas mixture, or to improve absorption efficiency, or to facilitate the recovery or removal of any acid vapor from remaining gases, or to facilitate the recovery or removal of acetic acid vapor from remaining gases, or prevent or minimize or reduce the concentration or partial pressure of acetic acid vapor in the remaining gases, or any combination thereof. For example, in some embodiments, the process employed to decompose calcium sulfite to calcium oxide and sulfur dioxide may form a gas mixture comprising sulfur dioxide. For example, in some embodiments, the partial pressure of sulfur dioxide in said gas mixture may be lower than 1 atm, or 0.9 atm, or 0.8 atm, or 0.7 atm, or 0.6 atm, or 0.5 atm, or 0.4 atm, or 0.3 atm, or 0.2 atm, or 0.1 atm, or 0.05 atm, or any combination thereof and/or wherein the volume percent concentration of sulfur dioxide in said gas mixture may be lower than 100%, or 90%, or 80%, or 70%, or 60%, or 50%, or 40%, or 30%, or 20%, or 10%, or 5%, or any combination thereof.
- Greater absorption rate or absorption efficiency.
- Solid-liquid separations may be easier or simpler or higher yielding. For example, in some embodiments, if the rate of precipitation is dependent on the mixing of two liquids, rather a precipitation reaction from a gas and a liquid, the formation of and/or separation of precipitates may be more controllable.

Example 4: Process for Producing Magnesium Oxide or Cement or Clinker with Alkali Intermediate

Note: Residual solids or undissolved solids, such as silicon dioxide or other undissolved solids, may be separated from the liquid solution using a solid-liquid separation.

Note: If CO₂(g) is produced, it may be desirable for said CO₂(g) to be produced at a high partial pressure CO₂(g), or purity CO₂(g), or to comprise captured CO₂(g).

Mg(CH₃COO)₂(aq)+Na₂SO₃(s or aq) custom character 2NaCH₃COO(aq)+MgSO₃(s) (2)

Note: MgSO₃(s) may be separated using a solid-liquid separation.

2NaCH₃COO(aq)+SO₂(g or aq)+H₂O(l or aq) custom character Na₂SO₃(aq)+2CH₃COOH(aq) (3)
Na₂SO₃(aq)+2CH₃COOH(aq)2CH₃COOH(aq or l)+Na₂SO₃(s) (4)

Note: CH₃COOH may be more soluble in water than Na₂SO₃. In some embodiments, water may be removed and/or Na₂SO₃may be separated or precipitated by, for example, including, but not limited to, evaporation, or distillation, or crystallization, or separation systems or methods described herein, or separation systems or methods described in the art, or any combination thereof.

Note: In some embodiments, magnesium sulfite(aq) may be present in the Na₂SO₃(aq)+2CH₃COOH(aq). In some embodiments, if present, magnesium sulfite may precipitate or crystalize before Na₂SO₃. In some embodiments, if present, magnesium sulfite may precipitate or crystalize before Na₂SO₃, which may enable the separation of at least a portion of magnesium sulfite from Na₂SO₃.

Note: Na₂SO₃(s) may be separated from CH₃COOH(aq or l) by a solid-liquid separation, which may include, but is not limited to, filter, or centrifuge, or decanter, or separation systems or methods described herein, or separation systems or methods described in the art, or any combination thereof.

Note: In some embodiments, CH₃COOH may evaporate with water vapor and/or condense with water vapor to form a distillate or condensate comprising CH₃COOH(aq).

MgSO₃(s) custom character MgO(s)+SO₂(g) (5)

Note: ‘(5)’ may comprise calcining CaSO₃(s), which may employ a kiln.

Note: CaSO₃(s) may be dried, or dehydrated, or both before, or during ‘(5)’.

Note: In some embodiments, it may be preferred to react SO₂(g) with NaCH₃COO(aq) to form Na₂SO₃(aq), and then react Na₂SO₃with Mg(CH₃COO)₂(aq) to form MgSO₃(s) because, for example, including, but not limited to, one or more or any combination of the following potential benefits:

- In some embodiments, it may be desirable to absorb SO₂(g) in an absorption column. Precipitate formation can be problematic in an absorption columns due to, for example, including, but not limited to, precipitate clogging packing material, or plates, or interfering with gas flows, or interfering with liquid flows, or forming scaling, or any combination thereof. The reaction of Mg(CH₃COO)₂(aq) with SO₂(g) may form a precipitate comprising MgSO₃(s), which may be problematic in some absorption columns or a gas absorption processes. The reaction of NaCH₃COO(aq) with SO₂(g) may, if desired, remain an aqueous solution or liquid solution throughout the reaction, because, for example, Na₂SO₃is soluble in water, which may be desirable in an absorption column.
- For example, it may be desirable to absorb SO₂(g) in an absorption column because the SO₂(g) may be at a dilute concentration, or a low partial pressure, or may comprise a gas mixture, or to improve absorption efficiency, or to facilitate the recovery or removal of any acid vapor from remaining gases, or any combination thereof. For example, in some embodiments, the process employed to decompose calcium sulfite to calcium oxide and sulfur dioxide may form a gas mixture comprising sulfur dioxide. For example, in some embodiments, the partial pressure of sulfur dioxide in said gas mixture may be lower than 1 atm, or 0.9 atm, or 0.8 atm, or 0.7 atm, or 0.6 atm, or 0.5 atm, or 0.4 atm, or 0.3 atm, or 0.2 atm, or 0.1 atm, or 0.05 atm, or any combination thereof and/or wherein the volume percent concentration of sulfur dioxide in said gas mixture may be lower than 100%, or 90%, or 80%, or 70%, or 60%, or 50%, or 40%, or 30%, or 20%, or 10%, or 5%, or any combination thereof.
- In some embodiments, if the SO₂(g) comprises gases in addition to SO₂(g), acetic acid vapor may be present in the remaining gases during or after the reaction of SO₂(g) with an acetate salt. If SO₂(g) is contacted with NaCH₃COO(aq), which may form aqueous phase Na₂SO₃(aq) and/or acetic acid, the reactor or absorption column may be configured such that NaCH₃COO(aq) entering the reactor or absorption column absorbs or recovers at least a portion of acetic acid vapor from the remaining gases. If SO₂(g) is contacted with NaCH₃COO(aq), which may form aqueous phase Na₂SO₃(aq) and/or acetic acid, the reactor or absorption column may be configured such that NaCH₃COO(aq) entering the reactor or absorption column absorbs or recovers at least a portion of acetic acid vapor from the remaining gases before or while NaCH₃COO(aq) is substantially reacted with SO₂(g). The employing NaCH₃COO(aq) may react with residual SO₂(g) potentially present in the remaining gases, which may avoid solid formation or solid handing issues which may occur if Ca(CH₃COO)₂(aq) is reacted with residual SO₂(g).
- Greater absorption rate or absorption efficiency.
- Solid-liquid separations may be easier or simpler or higher yielding. For example, if the rate of precipitation is dependent on the mixing of two liquids, rather than a gas and a liquid, the formation of and/or separation of precipitates may be more controlled.

Example 5: Process for Producing Calcium Oxide or Cement or Clinker with Alkali Intermediate with Recirculating Separation Process

Note: CaSO₃(s) may be separated using a solid-liquid separation.

Note: CH₃COOH(aq) may be present due to CH₃COOH(aq) being present in the retanate solution comprising Na₂SO₃(aq) from a membrane based separation of CH₃COOH(aq) and Na₂SO₃(aq).

2NaCH₃COO(aq)+SO₂(g or aq)+H₂O(l or aq) custom character Na₂SO₃(aq)+2CH₃COOH(aq) (3)
Na₂SO₃(aq)+2CH₃COOH(aq)2CH₃COOH(aq) separately from Na₂SO₃(aq)+2CH₃COOH(aq) (4)

Note: A portion of CH₃COOH(aq) may be separated from Na₂SO₃(aq) using a separation process, such as a membrane based process, such as reverse osmosis. In some embodiments, CH₃COOH(aq) may have a hydration radius or molar mass sufficiently small to permeate through a membrane, while said membrane may reject Na₂SO₃(aq). In some embodiments, Na₂SO₃(aq)+2CH₃COOH(aq) may be separated into a permeate solution comprising 2CH₃COOH(aq) and a retentate solution comprising Na₂SO₃(aq)+2CH₃COOH(aq).

CaSO₃(s) custom character CaO(s)+SO₂(g) (5)

Note: ‘(5)’ may comprise calcining CaSO₃(s), which may employ a kiln.

Note: CaSO₃(s) may be dried, or dehydrated, or both before or during ‘(5)’.

Example 6: Process for Producing Magnesium Oxide or Cement or Clinker with Alkali Intermediate with Recirculating Separation Process

Note: MgSO₃(s) may be separated using a solid-liquid separation.

Note: ‘(5)’ may comprise calcining MgSO₃(s), which may employ a kiln.

Note: MgSO₃(s) may be dried, or dehydrated, or both before or during ‘(5)’.

Example 7: Sodium Hydroxide Production from Sodium Sulfate Using Calcium Precipitation and Acid Intermediate

(1) React Material comprising Calcium, or Magnesium, or Other Alkaline Earth-Weak Acid Anion with Acetic Acid

CaCO₃(s or aq)+2CH₃COOH(aq) custom character Ca(CH₃COO)₂(aq)+CO₂(g)+H₂O(l or aq)
Calcium Silicate(s)+2CH₃COOH(aq)Ca(CH₃COO)₂(aq)+Silicon Dioxide(s)+H₂O(l or aq)
CaS(s)+2CH₃COOH(aq)Ca(CH₃COO)₂(aq)+H₂S(g)+H₂O(l or aq)
Calcium(Weak Acid Anion)+2CH₃COOH(aq)Ca(CH₃COO)₂(aq)+Weak Acid(s, or g, or l, or aq)+H₂O(l or aq)

Note: Residual solids or undissolved solids, such as silicon dioxide or other undissolved solids, may be separated from the liquid solution using a solid-liquid separation.

Note: CO₂(g) may comprise captured CO₂.

Note: In some embodiments, acetic acid vapor and/or water vapor may be separated or recovered from CO₂(g).

Ca(CH₃COO)₂(aq)+Na₂SO₄(s or aq) custom character 2NaCH₃COO(aq)+CaSO₄(s) (2)

Note: In some embodiments, Na₂SO₄(s) may be added directly to or dissolved in Ca(CH₃COO)₂(aq).

Note: In some embodiments, Na₂SO₄(s) may be dissolved in water or an aqueous solution to form Na₂SO₄(aq) before mixing with Ca(CH₃COO)₂(aq).

Note: In some embodiments, water may be added to the process to make up for water which may leave the process, for example, if NaOH(aq) is an output, or another aqueous solution is an output, or any combination thereof. In some embodiments, water may be added to the process by Na₂SO₄being in the form of Na₂SO₄(aq) or an aqueous solution comprising sodium sulfate, wherein at least a portion of the water in Na₂SO₄(aq) may comprise water added to the process. In some embodiments, Na₂SO₄(aq) may be provided or sourced as an aqueous solution. For example, in some embodiments, Na₂SO₄(aq) may be provided to the process in the form of Na₂SO₄(aq). In some embodiments, Na₂SO₄(aq) may be provided or sourced as a solid or Na₂SO₄(s), then dissolved in water to form Na₂SO₄(aq).

2NaCH₃COO(aq)+SO₂(g or aq)+H₂O(l or aq) custom character Na₂SO₃(aq)+2CH₃COOH(aq) (3)

Note: Ca(OH)₂(s or aq) may comprise a solid-liquid suspension, such as milk of lime.

Note: CaSO₃(s) may be separated using a solid-liquid separation.

CaSO₃(s) custom character CaO(s)+SO₂(g) (6)

Note: ‘(6)’ may comprise calcining CaSO₃(s), which may employ a kiln.

Note: CaSO₃(s) may be dried, or dehydrated, or both before or during ‘(6)’.

CaO(s)+Water(g or l or aq) custom character Ca(OH)₂(s or aq) (7)

Note: In some embodiments, CaO(s) may be employed to remove water vapor or facilitated drying of CaSO₃(s) before or during decomposition of CaSO₃(s) to CaO(s).

Note: In some embodiments, calcium oxide may be reacted directly with an aqueous solution comprising sodium sulfite to produce calcium sulfite and sodium hydroxide. In some embodiments, calcium oxide may be reacted directly with an aqueous solution comprising sodium sulfite to produce calcium sulfite and sodium hydroxide, which may comprise combining step ‘(5)‘ and step’(7)’.

Note: In some embodiments, calcium oxide may be reacted with water to produce an aqueous solution, or solid-liquid suspension, or milk of lime, or solid, or any combination thereof comprising calcium hydroxide.

2NaOH(aq or s) custom character 2NaOH(aq or s)+Water (8)

Note: In some embodiments, NaOH(aq) may be concentrated into an aqueous solution comprising a greater mass percent concentration of NaOH.

Note: In some embodiments, water may be removed and/or NaOH may be separated or precipitated by, for example, including, but not limited to, evaporation, or distillation, or crystallization, or separation systems or methods described herein, or separation systems or methods described in the art, or any combination thereof.

Note: In some embodiments, it may be desirable for NaOH to comprise a concentrated aqueous solution.

Example 8: Sodium Hydroxide Production from Sodium Sulfate Using Alkaline-Earth Precipitation and Acid Intermediate

Note: Residual solids or undissolved solids, such as silicon dioxide or other undissolved solids, may be separated from the liquid solution using a solid-liquid separation.

Mg(CH₃COO)₂(aq)+Na₂SO₄(aq) custom character 2NaCH₃COO(aq)+MgSO₄(s or aq) (2)
2NaCH₃COO(aq)+SO₂(g or aq)+H₂O(l or aq)Na₂SO₃(aq)+2CH₃COOH(aq) (3)
Na₂SO₃(aq)+2CH₃COOH(aq)2CH₃COOH(aq)+Na₂SO₃(s) (4)

Note: Mg(OH)₂(s or aq) may comprise a solid-liquid suspension, such as milk of lime.

Note: MgSO₃(s) may be separated using a solid-liquid separation.

MgSO₃(s) custom character MgO(s)+SO₂(g) (6)

Note: ‘(6)’ may comprise calcining MgSO₃(s), which may employ a kiln.

Note: MgSO₃(s) may be dried, or dehydrated, or both before or during ‘(6)’.

MgO(s)+Water(g or l or aq) custom character Mg(OH)₂(s or aq) (7)

Note: MgO(s) may be employed to remove water vapor or facilitated drying of MgSO₃(s) before or during decomposition of MgSO₃(s) to MgO(s).

2NaOH(aq or s) custom character 2NaOH(s)+Water (8)

Note: In some embodiments, it may be desirable for NaOH to comprise a concentrated aqueous solution.

Example 9: Sodium Hydroxide Production from Sodium Sulfate Using Calcium Precipitation and Acid Intermediate

Note: Residual solids or undissolved solids, such as silicon dioxide or other undissolved solids, may be separated from the liquid solution using a solid-liquid separation.

Ca(CH₃COO)₂(aq)+Na₂SO₄(aq) custom character 2NaCH₃COO(aq)+CaSO₄(s) (2)
2NaCH₃COO(aq)+SO₂(g or aq)+H₂O(l or aq)Na₂SO₃(aq)+2CH₃COOH(aq) (3)
Na₂SO₃(aq)+2CH₃COOH(aq)2CH₃COOH(aq)+Na₂SO₃(s) (4)

Note: Mg(OH)₂(s or aq) may comprise a solid-liquid suspension, such as milk of lime.

Note: MgSO₃(s) may be separated using a solid-liquid separation.

MgSO₃(s) custom character MgO(s)+SO₂(g) (6)

Note: ‘(6)’ may comprise calcining MgSO₃(s), which may employ a kiln.

Note: MgSO₃(s) may be dried, or dehydrated, or both before or during ‘(6)’.

MgO(s)+Water(g or l or aq) custom character Mg(OH)₂(s or aq) (7)

Note: MgO(s) may be employed to remove water vapor or facilitated drying of MgSO₃(s) before or during decomposition of MgSO₃(s) to MgO(s).

2NaOH(aq or s) custom character 2NaOH(s)+Water
Or
2NaOH(aq)2NaOH(aq—more concentrated)+Water (8)

Note: In some embodiments, it may be desirable for NaOH to comprise a concentrated aqueous solution.

Note: Residual MgSO₃(aq) may be present or dissolved in the solution comprising NaOH(aq). In some embodiments, during the concentrating of NaOH(aq) or removal of at least a portion of water from the NaOH(aq), at least a portion of the residual MgSO₃may precipitate or may be separated or recovered. For example, in some embodiments, MgSO₃(aq) may be less soluble in water than NaOH(aq). Separated or recovered MgSO₃may be transferred, for example, to step ‘(6)’.

Example 10: Sodium Carbonate Production from Sodium Sulfate Using Alkaline-Earth Precipitation and Acid Intermediate

Note: Ca(OH)₂(s or aq) may comprise a solid-liquid suspension, such as milk of lime.

Note: CaSO₃(s) may be separated using a solid-liquid separation.

Note: In some embodiments, Na₂SO₃(s) may be dissolved in water to form Na₂SO₃(aq) before step ‘(5)’. In some embodiments, water may provided from internally within the process, or water may be provided from an external source, or any combination thereof. For example, if net water is consumed, or water is in the sodium hydroxide or sodium carbonate product, or water is in the product, or any combination thereof, it may be desirable for a portion of the water to come from an external source.

CaSO₃(s) custom character CaO(s)+SO₂(g) (6)

Note: ‘(6)’ may comprise calcining CaSO₃(s), which may employ a kiln.

Note: CaSO₃(s) may be dried, or dehydrated, or both before or during ‘(6)’.

CaO(s)+Water(g or l or aq) custom character Ca(OH)₂(s or aq) (7)

Note: CaO(s) may be employed to remove water vapor or facilitated drying of CaSO₃(s) before or during decomposition of CaSO₃(s) to CaO(s).

Note: In some embodiments, CaO may be reacted directly with Na₂SO₃(s or aq) or an aqueous solution comprising sodium sulfite. For example, in some embodiments, step ‘(5)’ may be combined with step ‘(7)’

Note: In some embodiments, water may provided from internally within the process, or water may be provided from an external source, or any combination thereof. For example, if net water is consumed, or water is in the sodium hydroxide or sodium carbonate product, or water is in the product, or any combination thereof, it may be desirable for a portion of the water to come from an external source.

2NaOH(aq or s)+CO₂(g) custom character Na₂CO₃(s or aq)+H₂O(l or aq or g) (8)

Note: In some embodiments, CO₂may comprise a gas with a dilute concentration of carbon dioxide, which may include, but is not limited to, CO₂sources described herein or CO₂sources. In some embodiments, NaOH(aq) may be capable of reacting with a wide range of CO₂(g) concentrations, including, potentially, for example, very low CO₂(g) concentrations, such as CO₂(g) in air.

Note: In some embodiments, NaOH(aq or s) may be added to the ocean or sea, where it may react with CO₂or CO₂derivative ions or chemical species in the ocean or air and/or increase ocean pH.

Note: Na₂CO₃(s or aq) may be further reacted with carbon dioxide and/or water to form sodium bicarbonate.

Note: Na₂CO₃(s) may precipitate and/or be separated from the remaining solution. After precipitation, NaOH(s) may be added and/or dissolved in the remaining solution to, for example, make up for sodium lost during the precipitation and separation of Na₂CO₃(s).

Note: In some embodiments, Na₂CO₃(aq), which may comprise a ‘feed’ solution into a concentrating process, may be concentrated using an energy efficient concentrating method, such as reverse osmosis or electrodialysis or heat recovery distillation, at an elevated temperature and/or the resulting concentrate or retentate may be cooled to precipitate a portion of Na₂CO₃(s). In some embodiments, the remaining solution after precipitation and separation of Na₂CO₃(s) may be mixed with Na₂CO₃(aq) feed solution before heating the combined solution and/or concentrating the combined solution using an energy efficient concentrating method. In some embodiments, water recovered during the concentrating, such as water permeate, or diluate, or condensate, may be, including, but not limited to, one or more or any combination of the following: employed dissolve sodium sulfite and form aqueous sodium sulfite, or transferred to a reaction of calcium oxide with water to produce calcium hydroxide, or transferred to dissolve sodium sulfate.

Note: SO₂(g) from calcining CaSO₃may be further concentrated, or pressurized, or purified.

Note: SO₂(g) from calcining CaSO₃may be absorbed into water or an aqueous solution to form sulfurous acid or aqueous sulfur dioxide.

Note: Weak acid or weak acid anion may comprise an acid or acid anion with an acid strength lower than the acid strength of formic acid, or acetic acid, or propionic acid, or butyric acid, or citric acid, or lactic acid, or valeric acid, or caproic acid, or enanthic acid, or caprylic acid, or pelargonic acid, or capric acid, or carboxylic acid, or sulfurous acid.

Note: Weak acid or weak acid anion may comprise an acid or acid anion with a higher pKa than acetic acid, or carboxylic acid, or sulfurous acid.

Note: Acetic acid may be provided as an example acid with an acid strength greater than ‘Weak Acid’, and an acid strength lower than sulfurous acid or aqueous sulfur dioxide.

Note: Acetic acid may be provided as an example acid with an pKa lower than ‘Weak Acid’, and an pKa greater than sulfurous acid or aqueous sulfur dioxide.

Note: Calcium may be provided as an example alkaline earth. Other alkaline earths, which may include beryllium (Be), or magnesium (Mg), or calcium (Ca), or strontium (Sr), or barium (Ba), or radium (Ra), or any combination thereof, may be employed instead or in addition to calcium.

Example 11: Process for Producing Calcium Oxide or Cement or Clinker with Ammonia Intermediate

Note: Residual solids or undissolved solids, such as silicon dioxide or other undissolved solids, may be separated from the liquid solution using a solid-liquid separation.

Note: If CO₂(g) is produced, it may be desirable for said CO₂(g) to be produced at a high partial pressure CO₂(g), or purity CO₂(g), or to comprise captured CO₂(g).

Ca(CH₃COO)₂(aq)+(NH₄)₂SO₃(s or aq) custom character 2NH₄CH₃COO(aq)+CaSO₃(s) (2)

Note: CaSO₃(s) may be separated using a solid-liquid separation.

2NH₄CH₃COO(aq)+SO₂(g or aq)+H₂O(l or aq) custom character (NH₄)₂SO₃(aq)+2CH₃COOH(aq) (3)
(NH₄)₂SO₃(aq)+2CH₃COOH(aq)2CH₃COOH(aq)+(NH₄)₂SO₃(s) (4)

Note: CH₃COOH may be more soluble in water than (NH₄)₂SO₃. In some embodiments, water may be removed and/or (NH₄)₂SO₃may be separated or precipitated by, for example, including, but not limited to, evaporation, or distillation, or crystallization, or separation systems or methods described herein, or zero-liquid discharge methods described in the art, or separation systems or methods described in the art, or any combination thereof.

Note: In some embodiments, magnesium sulfite(aq) may be present in the (NH₄)₂SO₃(aq)+2CH₃COOH(aq). In some embodiments, if present, at least a portion of magnesium sulfite may begin to precipitate or crystalize before (NH₄)₂SO₃. In some embodiments, it may be desirable to separate at least a portion of the magnesium sulfite from (NH₄)₂SO₃.

Note: (NH₄)₂SO₃(s) may be separated from CH₃COOH(aq or l) by a solid-liquid separation, which may include, but is not limited to, filter, or centrifuge, or decanter, or separation systems or methods described herein, or separation systems or methods described in the art, or any combination thereof.

CaSO₃(s) custom character CaO(s)+SO₂(g) (5)

Note: ‘(5)’ may comprise calcining CaSO₃(s), which may employ a kiln.

Note: CaSO₃(s) may be dried, or dehydrated, or both before, or during ‘(5)’.

Note: In some embodiments, it may be preferred to react SO₂(g) with NH₄CH₃COO(aq) to form (NH₄)₂SO₃(aq), then react (NH₄)₂SO₃with Ca(CH₃COO)₂(aq) to form CaSO₃(s) because, for example, including, but not limited to, one or more or any combination of the following potential benefits:

- In some embodiments, it may be desirable to absorb SO₂(g) in an absorption column. Precipitate formation can be problematic in an absorption columns due to, for example, including, but not limited to, precipitate clogging packing material, or plates, or interfering with gas flows, or interfering with liquid flows, or forming scaling, or any combination thereof. The reaction of Ca(CH₃COO)₂(aq) with SO₂(g) may form a precipitate comprising CaSO₃(s), which may be problematic in some absorption columns or a gas absorption processes. The reaction of NH₄CH₃COO(aq) with SO₂(g) may, if desired, remain an aqueous solution or liquid solution throughout the reaction, because, for example, (NH₄)₂SO₃is soluble in water, which may be desirable in an absorption column.
- For example, it may be desirable to absorb SO₂(g) in an absorption column because the SO₂(g) may be at a dilute concentration, or a low partial pressure, or may comprise a gas mixture, or to improve absorption efficiency, or any combination thereof. For example, in some embodiments, the process employed to decompose calcium sulfite to calcium oxide and sulfur dioxide may form a gas mixture comprising sulfur dioxide. For example, in some embodiments, the partial pressure of sulfur dioxide in said gas mixture may be lower than 1 atm, or 0.9 atm, or 0.8 atm, or 0.7 atm, or 0.6 atm, or 0.5 atm, or 0.4 atm, or 0.3 atm, or 0.2 atm, or 0.1 atm, or 0.05 atm, or any combination thereof and/or wherein the volume percent concentration of sulfur dioxide in said gas mixture may be lower than 100%, or 90%, or 80%, or 70%, or 60%, or 50%, or 40%, or 30%, or 20%, or 10%, or 5%, or any combination thereof.
- Greater absorption rate or absorption efficiency.
- Solid-liquid separations may be easier or simpler or higher yielding. For example, if the rate of precipitation is dependent on the mixing of two liquids, rather than a gas and a liquid, the formation of and/or separation of precipitates may be more controlled.

Example 12: Process for Producing Alkaline-Earth Oxide or Cement or Clinker with Ammonia Intermediate

Note: Residual solids or undissolved solids, such as silicon dioxide or other undissolved solids, may be separated from the liquid solution using a solid-liquid separation.

Note: If CO₂(g) is produced, it may be desirable for said CO₂(g) to be produced at a high partial pressure CO₂(g), or purity CO₂(g), or to comprise captured CO₂(g).

Mg(CH₃COO)₂(aq)+(NH₄)₂SO₃(s or aq) custom character 2NH₄CH₃COO(aq)+MgSO₃(s) (2)

Note: MgSO₃(s) may be separated using a solid-liquid separation.

2NH₄CH₃COO(aq)+SO₂(g or aq)+H₂O(l or aq) custom character (NH₄)₂SO₃(aq)+2CH₃COOH(aq) (3)
(NH₄)₂SO₃(aq)+2CH₃COOH(aq)2CH₃COOH(aq)+(NH₄)₂SO₃(s) (4)

Note: CH₃COOH may be more soluble in water than (NH₄)₂SO₃. In some embodiments, water may be removed and/or (NH₄)₂SO₃may be separated or precipitated by, for example, including, but not limited to, evaporation, or distillation, or crystallization, or separation systems or methods described herein, or separation systems or methods described in the art, or any combination thereof.

Note: In some embodiments, magnesium sulfite(aq) may be present in the (NH₄)₂SO₃(aq)+2CH₃COOH(aq). In some embodiments, if present, magnesium sulfite may begin to precipitate or crystalize before (NH₄)₂SO₃.

Note: (NH₄)₂SO₃(s) may be separated from CH₃COOH(aq) by a solid-liquid separation, which may include, but is not limited to, filter, or centrifuge, or decanter, or separation systems or methods described herein, or separation systems or methods described in the art, or any combination thereof.

MgSO₃(s) custom character MgO(s)+SO₂(g) (5)

Note: ‘(5)’ may comprise calcining CaSO₃(s), which may employ a kiln.

Note: CaSO₃(s) may be dried, or dehydrated, or both before, or during ‘(5)’.

Note: In some embodiments, it may be preferred to react SO₂(g) with NH₄CH₃COO(aq) to form (NH₄)₂SO₃(aq), then react (NH₄)₂SO₃with Mg(CH₃COO)₂(aq) to form MgSO₃(s) because, for example, including, but not limited to, one or more or any combination of the following potential benefits:

- In some embodiments, it may be desirable to absorb SO₂(g) in an absorption column. Precipitate formation can be problematic in an absorption columns due to, for example, including, but not limited to, precipitate clogging packing material, or plates, or interfering with gas flows, or interfering with liquid flows, or forming scaling, or any combination thereof. The reaction of Mg(CH₃COO)₂(aq) with SO₂(g) may form a precipitate comprising MgSO₃(s), which may be problematic in some absorption columns or a gas absorption processes. The reaction of NH₄CH₃COO(aq) with SO₂(g) may, if desired, remain an aqueous solution or liquid solution throughout the reaction, because, for example, Na₂SO₃is soluble in water, which may be desirable in an absorption column.
- For example, it may be desirable to absorb SO₂(g) in an absorption column because the SO₂(g) may be at a dilute concentration, or a low partial pressure, or may comprise a gas mixture, or to improve absorption efficiency, or any combination thereof. For example, in some embodiments, the process employed to decompose calcium sulfite to calcium oxide and sulfur dioxide may form a gas mixture comprising sulfur dioxide. For example, in some embodiments, the partial pressure of sulfur dioxide in said gas mixture may be lower than 1 atm, or 0.9 atm, or 0.8 atm, or 0.7 atm, or 0.6 atm, or 0.5 atm, or 0.4 atm, or 0.3 atm, or 0.2 atm, or 0.1 atm, or 0.05 atm, or any combination thereof and/or wherein the volume percent concentration of sulfur dioxide in said gas mixture may be lower than 100%, or 90%, or 80%, or 70%, or 60%, or 50%, or 40%, or 30%, or 20%, or 10%, or 5%, or any combination thereof.
- Greater absorption rate or absorption efficiency.
- Solid-liquid separations may be easier or simpler or higher yielding. For example, if the rate of precipitation is dependent on the mixing of two liquids, rather than a gas and a liquid, the formation of and/or separation of precipitates may be more controlled.

Example 13: Process for Producing Calcium Oxide or Cement or Clinker with Ammonia Intermediate with Recirculating Separation

Note: CaSO₃(s) may be separated using a solid-liquid separation.

Note: CH₃COOH(aq) may be present due to CH₃COOH(aq) being present in the retentate solution comprising (NH₄)₂SO₃(aq) from a membrane based separation of CH₃COOH(aq) and (NH₄)₂SO₃(aq).

2(NH₄)CH₃COO(aq)+SO₂(g or aq)+H₂O(l or aq) custom character (NH₄)₂SO₃(aq)+2CH₃COOH(aq) (3)
(NH₄)₂SO₃(aq)+2CH₃COOH(aq)2CH₃COOH(aq) separately from (NH₄)₂SO₃(aq)+2CH₃COOH(aq) (4)

Note: A portion of CH₃COOH(aq) may be separated from (NH₄)₂SO₃(aq) using a separation process, such as a membrane based process, such as reverse osmosis. In some embodiments, CH₃COOH(aq) may have a hydration radius or molar mass sufficiently small to permeate through a membrane, while said membrane may reject (NH₄)₂SO₃(aq). In some embodiments, (NH₄)₂SO₃(aq)+2CH₃COOH(aq) may be separated into a permeate solution comprising 2CH₃COOH(aq) and a retentate solution comprising (NH₄)₂SO₃(aq)+2CH₃COOH(aq).

CaSO₃(s) custom character CaO(s)+SO₂(g) (5)

Note: ‘(5)’ may comprise calcining CaSO₃(s), which may employ a kiln.

Note: CaSO₃(s) may be dried, or dehydrated, or both before or during ‘(5)’.

Example 14: Process for Producing Alkaline-Earth Oxide or Cement or Clinker with Ammonia Intermediate with Recirculating Separation

Note: MgSO₃(s) may be separated using a solid-liquid separation.

Note: CH₃COOH(aq) may be present due to CH₃COOH(aq) being present in the retanate solution comprising (NH₄)₂SO₃(aq) from a membrane based separation of CH₃COOH(aq) and (NH₄)₂SO₃(aq).

2NH₄CH₃COO(aq)+SO₂(g or aq)+H₂O(l or aq) custom character (NH₄)₂SO₃(aq)+2CH₃COOH(aq) (3)
(NH₄)₂SO₃(aq)+2CH₃COOH(aq)2CH₃COOH(aq) separately from (NH₄)₂SO₃(aq)+2CH₃COOH(aq) (4)

Note: ‘(6)’ may comprise calcining MgSO₃(s), which may employ a kiln.

Note: MgSO₃(s) may be dried, or dehydrated, or both before or during ‘(6)’.

Example 15: Ammonia Production from Ammonium Sulfate Using Calcium Precipitation and Acid Intermediate

Note: Residual solids or undissolved solids, such as silicon dioxide or other undissolved solids, may be separated from the liquid solution using a solid-liquid separation.

Ca(CH₃COO)₂(aq)+(NH₄)₂SO₄(aq) custom character 2NH₄CH₃COO(aq)+CaSO₄(s) (2)
2NH₄CH₃COO(aq)+SO₂(g or aq)+H₂O(l or aq)(NH₄)₂SO₃(aq)+2CH₃COOH(aq) (3)
(NH₄)₂SO₃(aq)+2CH₃COOH(aq)2CH₃COOH(aq or l)+(NH₄)₂SO₃(s)+Water (4)

Note: CH₃COOH may be more soluble in water than (NH₄)₂SO₃. In some embodiments, water may be removed and/or (NH₄)₂SO₃may be separated or precipitated by, for example, including, but not limited to, evaporation, or distillation, or crystallization, or separation systems or methods described herein, or separation systems or methods described in the art, or any combination thereof.

Note: Ca(OH)₂(s or aq) may comprise a solid-liquid suspension, such as milk of lime.

Note: CaSO₃(s) may be separated using a solid-liquid separation.

Note: 2NH₃(aq) may be separated into ammonia gas and water if desired.

CaSO₃(s) custom character CaO(s)+SO₂(g) (6)

Note: ‘(6)’ may comprise calcining CaSO₃(s), which may employ a kiln.

Note: CaSO₃(s) may be dried, or dehydrated, or both before or during ‘(6)’.

CaO(s)+Water(g or l or aq) custom character Ca(OH)₂(s or aq) (7)

Note: CaO(s) may be employed to remove water vapor or facilitated drying of CaSO₃(s) before or during decomposition of CaSO₃(s) to CaO(s).

2NH₄OH(aq) or 2NH₃(aq) custom character 2NH₃(g or l or aq)+Water (8)

Note: In some embodiments, it may be desirable to produce ammonia gas or liquid ammonia. In some embodiments, it may be desirable to produce a high concentration or greater concentration aqueous ammonia or ammonium hydroxide solution.

Note: In some embodiments, it may be desirable for 2NH₄OH(aq) or 2NH₃(aq) to comprise an aqueous solution. If example, in some embodiments, it may be desirable for to keep aqueous ammonia or ammonium hydroxide at an aqueous phase.

Example 16: Ammonia Production from Ammonium Sulfate Using Alkaline-Earth Precipitation and Acid Intermediate

Note: Residual solids or undissolved solids, such as silicon dioxide or other undissolved solids, may be separated from the liquid solution using a solid-liquid separation.

Mg(CH₃COO)₂(aq)+(NH₄)₂SO₄(aq) custom character 2NH₄CH₃COO(aq)+MgSO₄(s or aq) (2)
2NH₄CH₃COO(aq)+SO₂(g or aq)+H₂O(l or aq)(NH₄)₂SO₃(aq)+2CH₃COOH(aq) (3)
(NH₄)₂SO₃(aq)+2CH₃COOH(aq)2CH₃COOH(aq)+(NH₄)₂SO₃(s) (4)

Note: CH₃COOH may be more soluble in water than (NH₄)₂SO₃. In some embodiments, water may be removed and/or (NH₄)₂SO₃may be separated or precipitated by, for example, including, but not limited to, evaporation, or distillation, or crystallization, or separation systems or methods described herein, or separation systems or methods described in the art, or any combination thereof.

Note: Mg(OH)₂(s or aq) may comprise a solid-liquid suspension, such as milk of lime.

Note: MgSO₃(s) may be separated using a solid-liquid separation.

Note: 2NH₃(aq) may be separated into ammonia gas and water if desired.

MgSO₃(s) custom character MgO(s)+SO₂(g) (6)

Note: ‘(6)’ may comprise calcining MgSO₃(s), which may employ a kiln.

Note: MgSO₃(s) may be dried, or dehydrated, or both before or during ‘(6)’.

MgO(s)+Water(g or l or aq) custom character Mg(OH)₂(s or aq) (7)

Note: MgO(s) may be employed to remove water vapor or facilitated drying of MgSO₃(s) before or during decomposition of MgSO₃(s) to MgO(s).

2NH₄OH(aq) or 2NH₃(aq) custom character 2NH₃(g or l or aq)+Water (8)

Example 17: Ammonia Production from Ammonium Sulfate Using Alkaline-Earth Precipitation and Acid Intermediate

Note: Residual solids or undissolved solids, such as silicon dioxide or other undissolved solids, may be separated from the liquid solution using a solid-liquid separation.

Ca(CH₃COO)₂(aq)+(NH₄)₂SO₄(aq) custom character 2NH₄CH₃COO(aq)+CaSO₄(s) (2)
2NH₄CH₃COO(aq)+SO₂(g or aq)+H₂O(l or aq)(NH₄)₂SO₃(aq)+2CH₃COOH(aq) (3)
(NH₄)₂SO₃(aq)+2CH₃COOH(aq)2CH₃COOH(aq)+(NH₄)₂SO₃(s) (4)

Note: CH₃COOH may be more soluble in water than (NH₄)₂SO₃. In some embodiments, water may be removed and/or (NH₄)₂SO₃may be separated or precipitated by, for example, including, but not limited to, evaporation, or distillation, or crystallization, or separation systems or methods described herein, or separation systems or methods described in the art, or any combination thereof.

Note: Mg(OH)₂(s or aq) may comprise a solid-liquid suspension, such as milk of lime.

Note: MgSO₃(s) may be separated using a solid-liquid separation.

Note: 2NH₃(aq) may be separated into ammonia gas and water if desired.

MgSO₃(s) custom character MgO(s)+SO₂(g) (6)

Note: ‘(6)’ may comprise calcining MgSO₃(s), which may employ a kiln.

Note: MgSO₃(s) may be dried, or dehydrated, or both before or during ‘(6)’.

MgO(s)+Water(g or l or aq) custom character Mg(OH)₂(s or aq) (7)

Example 18: Ammonium Carbonate or Ammonium Bicarbonate or Ammonium Carbamate or Urea Production Using Acid Intermediate

Note: Residual solids or undissolved solids, such as silicon dioxide or other undissolved solids, may be separated from the liquid solution using a solid-liquid separation.

Ca(CH₃COO)₂(aq)+(NH₄)₂SO₄(aq) custom character 2NH₄CH₃COO(aq)+CaSO₄(s) (2)
2NH₄CH₃COO(aq)+SO₂(g or aq)+H₂O(l or aq)(NH₄)₂SO₃(aq)+2CH₃COOH(aq) (3)
(NH₄)₂SO₃(aq)+2CH₃COOH(aq)2CH₃COOH(aq)+(NH₄)₂SO₃(s) (4)

Note: Ca(OH)₂(s or aq) may comprise a solid-liquid suspension, such as milk of lime.

Note: CaSO₃(s) may be separated using a solid-liquid separation.

CaSO₃(s) custom character CaO(s)+SO₂(g) (6)

Note: ‘(6)’ may comprise calcining CaSO₃(s), which may employ a kiln.

Note: CaSO₃(s) may be dried, or dehydrated, or both before or during ‘(6)’.

CaO(s)+Water(g or l or aq) custom character Ca(OH)₂(s or aq) (7)

Note: CaO(s) may be employed to remove water vapor or facilitated drying of CaSO₃(s) before or during decomposition of CaSO₃(s) to CaO(s).

2NH₄OH(aq)+CO₂(g) custom character (NH₄)₂CO₃(s or aq)+H₂O(l or aq or g) (8)

Note: In some embodiments, (NH₄)₂CO₃(s or aq) may be further reacted with carbon dioxide and/or water to form sodium bicarbonate.

Note: In some embodiments, the aqueous solution may comprise a mixture of ammonium carbonate, or ammonium bicarbonate, or ammonium carbamate, or ammonium sesquicarbonate, or free ammonia, or aqueous ammonia, or ammonium hydroxide, or any combination thereof.

Example 19: Direct Air Capture, or Capture of CO₂from Air, or CO₂Capture Using Alkaline-Earth, Sulfur Dioxide, and Acid

(1) Reaction of alkaline-earth oxide, or alkaline-earth hydroxide, or any combination thereof with carbon dioxide.

CaO(s)+CO₂(g) custom character CaCO₃(s)
and/or
Ca(OH)₂(s or aq)+CO₂(g)CaCO₃(s)+H₂O(g or l)
CaCO₃(s or aq)+2CH₃COOH(aq)Ca(CH₃COO)₂(aq)+CO₂(g) (2)

Note: CO₂(g) in ‘(2)’ may comprise captured CO₂(g).

Ca(CH₃COO)₂(aq)+SO₂(g) custom character CaSO₃(s)+2CH₃COOH(aq) (3)

Note: In some embodiments, SO₂(g) may comprise a gas comprising a dilute concentration of SO₂(g).

CaSO₃(s) custom character CaO(s)+SO₂(g) (4)
CaO(s)+H₂O(l or g)Ca(OH)₂(s or aq) (5)

Example 20: Direct Air Capture, or Capture of CO₂from Air, or CO₂Capture Using Alkaline-Earth, Sulfur Dioxide, and Acid

(1) Reaction of alkaline-earth oxide, or alkaline-earth hydroxide, or any combination thereof with carbon dioxide.

MgO(s)+CO₂(g) custom character MgCO₃(s)
and/or
Mg(OH)₂(s or aq)+CO₂(g)MgCO₃(s)+H₂O(g or l)
MgCO₃(s or aq)+2CH₃COOH(aq)Mg(CH₃COO)₂(aq)+CO₂(g) (2)

Note: CO₂(g) in ‘(2)’ may comprise captured CO₂(g).

Mg(CH₃COO)₂(aq)+SO₂(g) custom character MgSO₃(s)+2CH₃COOH(aq) (3)

Note: In some embodiments, SO₂(g) may comprise a gas comprising a dilute concentration of SO₂(g).

MgSO₃(s) custom character MgO(s)+SO₂(g) (4)
MgO(s)+H₂O(l or g)Mg(OH)₂(s or aq) (5)

Example 21: Direct Air Capture, or Capture of CO₂from Air, or CO₂Capture Using Alkali, Alkaline-Earth, and Sulfur Dioxide

2NaOH(aq)+CO₂(g) custom character Na₂CO₃(aq or s)+H₂O(g or l) (1)
Na₂CO₃(aq or s)+SO₂(l or aq)Na₂SO₃(aq or s)+CO₂(g) (2)

Note: CO₂(g) in ‘(2)’ may comprise captured CO₂(g).

Na₂SO₃(aq or s)+Ca(OH)₂(s or aq) custom character 2NaOH(aq)+CaSO₃(s) (3)
CaSO₃(s)CaO(s)+SO₂(g) (4)
CaO(s)+H₂O(l or g)Ca(OH)₂(s or aq) (5)

Example 22: Direct Air Capture, or Capture of CO₂from Air, or CO₂Capture Using Alkali, Alkaline-Earth, and Sulfur Dioxide

2NaOH(aq)+CO₂(g) custom character Na₂CO₃(aq or s)+H₂O(g or l) (1)
Na₂CO₃(aq or s)+SO₂(l or aq)Na₂SO₃(aq or s)+CO₂(g) (2)

Note: CO₂(g) in ‘(2)’ may comprise captured CO₂(g).

Na₂SO₃(aq or s)+Mg(OH)₂(s or aq) custom character 2NaOH(aq)+MgSO₃(s) (3)
MgSO₃(s)MgO(s)+SO₂(g) (4)
MgO(s)+H₂O(l or g)Mg(OH)₂(s or aq) (5)

Example 23: Direct Air Capture, or Capture of CO₂from Air, or CO₂Capture Using Alkali, Alkaline-Earth, and Sulfur Dioxide

2NaOH(aq)+CO₂(g) custom character Na₂CO₃(aq or s)+H₂O(g or l) (1)
Na₂CO₃(aq or s)+2CH₃COOH(l or aq)2NaCH₃COO(aq)+CO₂(g) (2)

Note: CO₂(g) in ‘(2)’ may comprise captured CO₂(g).

2NaCH₃COO(aq)+SO₂(g) custom character Na₂SO₃(aq or s)+2CH₃COOH(aq) (3)

Note: In some embodiments, SO₂(g) may comprise a gas comprising a dilute concentration of SO₂(g).

Separate Na₂SO₃from 2CH₃COOH (4)
Na₂SO₃(aq or s)+Ca(OH)₂(s or aq) custom character 2NaOH(aq)+CaSO₃(s) (5)
CaSO₃(s)CaO(s)+SO₂(g) (6)
CaO(s)+H₂O(l or g)Ca(OH)₂(s or aq) (7)

Example 24: Direct Air Capture, or Capture of CO₂from Air, or CO₂Capture Using Alkali, Alkaline-Earth, and Sulfur Dioxide

2NaOH(aq)+CO₂(g) custom character Na₂CO₃(aq or s)+H₂O(g or l) (1)
Na₂CO₃(aq or s)+2CH₃COOH(l or aq)2NaCH₃COO(aq)+CO₂(g) (2)

Note: CO₂(g) in ‘(2)’ may comprise captured CO₂(g).

2NaCH₃COO(aq)+SO₂(g) custom character Na₂SO₃(aq or s)+2CH₃COOH(aq) (3)

Note: In some embodiments, SO₂(g) may comprise a gas comprising a dilute concentration of SO₂(g).

Separate Na₂SO₃from 2CH₃COOH (4)
Na₂SO₃(aq or s)+Mg(OH)₂(s or aq) custom character 2NaOH(aq)+MgSO₃(s) (5)
MgSO₃(s)MgO(s)+SO₂(g) (6)
MgO(s)+H₂O(l or g)Mg(OH)₂(s or aq) (7)

Example 25: CO₂Capture with Decoupled CO₂Absorption or Adsorption, CO₂Desorption or Displacement, and Reagent Regeneration

(1) CO₂Absorption: CO₂may be absorbed or adsorbed in calcium oxide, or calcium hydroxide, or calcium hydroxide suspension, such as milk of lime, or any combination thereof to produce calcium carbonate solid or suspension.

Ca(OH)₂(s or aq)+CO₂(g) custom character CaCO₃(s)+H₂O(l or g)

Note: Calcium hydroxide suspension may be transported to the absorption location and/or stored at or near the absorption location.

Note: Calcium carbonate solid may be separated by settling, or solid-liquid separation, or any combination thereof.

Note: Calcium carbonate may be stored at or near the absorption or adsorption location. Calcium carbonate may be transported to an application using calcium carbonate. Calcium carbonate may be transferred to the CO₂desorption or displacement location. In some embodiments, the CO₂desorption or displacement location may be the same as the CO₂absorption or adsorption location. In some embodiments, the CO₂desorption or displacement location may be different than the CO₂absorption or adsorption location. For example, in some embodiments, it may be desirable for the CO₂absorption or adsorption to be located at multiple distributed sites, while the Regeneration may be conducted at a larger and/or more centralized facility or site.

(2) CO₂Desorption or Displacement: Calcium carbonate may be reacted with acetic acid to produce calcium acetate and carbon dioxide.

CaCO₃(s)+2CH₃COOH custom character Ca(CH₃COO)₂(aq)+CO₂(g)

- Note: Calcium carbonate may be stored at or near the CO₂Desorption or Displacement location.
- Note: Acetic acid may be stored at or near the CO₂Desorption or Displacement location.
- Note: CO₂Desorption or Displacement may be located at an application requiring carbon dioxide, or high purity carbon dioxide, or high pressure carbon dioxide, or captured carbon dioxide, or any combination thereof. For example, CO₂Desorption or Displacement may be located at a site requiring CO₂enhanced oil recovery (EOR).
- Note: Calcium acetate may comprise an aqueous calcium acetate solution, or calcium acetate solid, or any combination thereof.
- Note: Calcium acetate may be stored at or near the CO₂Desorption or Displacement. Calcium acetate may be transported to an application using calcium acetate. Calcium acetate may be transferred to at or near the Regeneration location. In some embodiments, the CO₂desorption or displacement location may be the same as Regeneration location. In some embodiments, the CO₂desorption or displacement location may be different than the Regeneration location. For example, in some embodiments, it may be desirable for the CO₂Desorption or Displacement to be located at multiple distributed sites, while the Regeneration may be conducted at a larger and/or more centralized facility or site.
- Note: Acetic acid vapor may be present in the CO₂(g). In some embodiments, acetic acid vapor may be at least partially removed from CO₂(g) by, for example, including, but not limited to, one or more or any combination of the following: contacting CO₂(g) comprising a portion of acetic acid vapor with CaCO₃, or contacting CO₂(g) comprising a portion of acetic acid vapor with sodium carbonate, or contacting CO₂(g) comprising a portion of acetic acid vapor with an alkali carbonate, or compression, or cooling, or condensing, or cryo-separation, or freeze separation.

(3) Regeneration: Calcium acetate may be reacted with sulfur dioxide to produce calcium sulfite. Calcium sulfite may be converted into calcium oxide and sulfur dioxide. Calcium oxide may be reacted with water to form a calcium hydroxide suspension, such as milk of lime.

Ca(CH₃COO)₂(aq)+SO₂(g or aq) custom character CaSO₃(s)+2CH₃COOH(aq)
CaSO₃(s)CaO(s)+SO₂(g)
CaO(s)+H₂O(g or l)Ca(OH)₂(s or aq)

Note: Calcium oxide or calcium hydroxide may be transported to the CO₂Absorption or Adsorption location.

Note: Acetic acid may be transported to the CO₂Desorption or Displacement location.

Note: It may be desirable for the regeneration to comprise a centralized facility, or a facility which may benefit from economies of scale, or any combination thereof.

Example 26: CO₂Capture with Decoupled CO₂Absorption or Adsorption, CO₂Desorption or Displacement, and Reagent Regeneration

(2) CO₂Desorption or Displacement: Calcium carbonate may be reacted with aqueous sulfurous acid to produce calcium sulfite and carbon dioxide.

CaCO₃(s)+SO₂(aq) custom character CaSO₃(s)+CO₂(g)

- Note: SO₂(g) vapor may be present in the CO₂(g). In some embodiments, SO₂(g) may be at least partially removed from CO₂(g) by, for example, including, but not limited to, one or more or any combination of the following: contacting CO₂(g) comprising a portion of SO₂(g) with CaCO₃, or contacting CO₂(g) comprising a portion of SO₂(g) with sodium carbonate, or contacting CO₂(g) comprising a portion of SO₂(g) with an alkali carbonate, or compression, or cooling, or condensing, or cryo-separation, or freeze separation.

(3) Regeneration: Calcium sulfite is converted into calcium oxide and sulfur dioxide. Calcium oxide is reacted with water to form a calcium hydroxide suspension, such as milk of lime.

CaSO₃(s) custom character CaO(s)+SO₂(g)
CaO(s)+H₂O(g or l)Ca(OH)₂(s or aq)

Example 27: CO₂Capture with Decoupled CO₂Absorption or Adsorption, CO₂Desorption or Displacement, and Reagent Regeneration

(1) CO₂Adsorption: CO₂adsorption or absorption in calcium oxide or calcium hydroxide to produce calcium carbonate solid

CaO(s)+CO₂(g) custom character CaCO₃(s)
Ca(OH)₂(s or aq)+CO₂(g)CaCO₃(s)+H₂O(l or g)

(3) Regeneration: Calcium acetate may be reacted with sulfur dioxide to produce calcium sulfite. Calcium sulfite is converted into calcium oxide and sulfur dioxide. Calcium oxide may be reacted with water to form a calcium hydroxide. In some embodiments, calcium hydroxide may form due to reaction of calcium oxide with water vapor.

Ca(CH₃COO)₂(aq)+SO₂(g or aq) custom character CaSO₃(s)+2CH₃COOH(aq)
CaSO₃(s)CaO(s)+SO₂(g)
CaO(s)+H₂O(g or l)Ca(OH)₂(s or aq)

Example 28: CO₂Capture with Decoupled CO₂Absorption or Adsorption, CO₂Desorption or Displacement, and Reagent Regeneration

(1) CO₂Adsorption: CO₂adsorption or absorption in calcium oxide or calcium hydroxide to produce calcium carbonate solid.

CaO(s)+CO₂(g) custom character CaCO₃(s)
Ca(OH)₂(s or aq)+CO₂(g)CaCO₃(s)+H₂O(l or g)

(2) CO₂Desorption or Displacement: Calcium carbonate may be reacted with sulfurous acid to produce calcium sulfite and carbon dioxide.

CaCO₃(s)+2CH₃COOH custom character Ca(CH₃COO)₂(aq)+CO₂(g)

(3) Regeneration: Calcium sulfite may be converted into calcium oxide and sulfur dioxide. Calcium oxide may be reacted with water to form a calcium hydroxide. In some embodiments, calcium hydroxide may form due to reaction of calcium oxide with water vapor.

Ca(CH₃COO)₂(aq)+SO₂(g or aq) custom character CaSO₃(s)+2CH₃COOH(aq)
CaSO₃(s)CaO(s)+SO₂(g)
CaO(s)+H₂O(g or l)Ca(OH)₂(s or aq)

Example 29: CO₂Capture with Decoupled CO₂Absorption or Adsorption, CO₂Desorption or Displacement, and Reagent Regeneration

(1) CO₂Absorption: CO₂absorption in sodium hydroxide solution to produce sodium carbonate solution or sodium carbonate precipitate. If sodium carbonate precipitate forms, sodium carbonate precipitate may be separated using, for example, a solid-liquid separation method.

2NaOH(aq or s)+CO₂(g) custom character Na₂CO₃(aq or s)+H₂O(l or aq or g)

Note: Sodium hydroxide solid or solution may be transported to the absorption location and/or stored at or near the absorption location.

Note: Sodium carbonate may be stored at or near the absorption or adsorption location. Sodium carbonate may be transported to an application using calcium carbonate. Sodium carbonate may be transferred to the CO₂desorption or displacement location. In some embodiments, the CO₂desorption or displacement location may be the same as the CO₂absorption or adsorption location. In some embodiments, the CO₂desorption or displacement location may be different than the CO₂absorption or adsorption location. For example, in some embodiments, it may be desirable for the CO₂absorption or adsorption to be located at multiple distributed sites, while the Regeneration may be conducted at a larger and/or more centralized facility or site.

(2) CO₂Desorption or Displacement: Sodium carbonate may be reacted with acetic acid to produce sodium acetate and carbon dioxide.

Na₂CO₃(aq or s)+2CH₃COOH custom character 2NaCH₃COO+CO₂(g)

- Note: Sodium carbonate may be stored at or near the CO₂Desorption or Displacement location.
- Note: Acetic acid may be stored at or near the CO₂Desorption or Displacement location.
- Note: CO₂Desorption or Displacement may be located at an application requiring carbon dioxide, or high purity carbon dioxide, or high pressure carbon dioxide, or captured carbon dioxide, or any combination thereof. For example, CO₂Desorption or Displacement may be located at a site requiring CO₂enhanced oil recovery (EOR).
- Note: Sodium acetate may comprise an aqueous calcium acetate solution, or sodium acetate solid, or any combination thereof.
- Note: Sodium acetate may be stored at or near the CO₂Desorption or Displacement. Sodium acetate may be transported to an application using sodium acetate. Sodium acetate may be transferred to at or near the Regeneration location. In some embodiments, the CO₂desorption or displacement location may be the same as Regeneration location. In some embodiments, the CO₂desorption or displacement location may be different than the Regeneration location. For example, in some embodiments, it may be desirable for the CO₂Desorption or Displacement to be located at multiple distributed sites, while the Regeneration may be conducted at a larger and/or more centralized facility or site.
- Note: Acetic acid vapor may be present in the CO₂(g). In some embodiments, acetic acid vapor may be at least partially removed from CO₂(g) by, for example, including, but not limited to, one or more or any combination of the following: contacting CO₂(g) comprising a portion of acetic acid vapor with CaCO₃, or contacting CO₂(g) comprising a portion of acetic acid vapor with sodium carbonate, or contacting CO₂(g) comprising a portion of acetic acid vapor with an alkali carbonate, or compression, or cooling, or condensing, or cryo-separation, or freeze separation.

(3) Regeneration: Sodium acetate may be reacted with sulfur dioxide to produce sodium sulfite and acetic acid. Sodium sulfite may be separated from acetic acid. Sodium sulfite may be reacted with calcium hydroxide, or calcium oxide, or calcium hydroxide suspension, or any combination thereof to produce sodium hydroxide and calcium sulfite. Calcium sulfite solid may be separated from sodium hydroxide solution. Calcium sulfite solid may be converted into calcium oxide and sulfur dioxide. Calcium oxide may be reacted with water to produce calcium hydroxide or calcium hydroxide suspension.

2NaCH₃COO+SO₂(g or aq) custom character Na₂SO₃(aq or s)+2CH₃COOH(aq)
Separate Na₂SO₃and 2CH₃COOH
Na₂SO₃(aq or s)+Ca(OH)₂(s or aq)CaSO₃(s)+2NaOH
CaSO₃(s)CaO(s)+SO₂(g)
CaO(s)+H₂O(g or l)Ca(OH)₂(s or aq)

- Note: Sodium hydroxide may be transported to the CO₂Absorption or Adsorption location.
- Note: Acetic acid may be transported to the CO₂Desorption or Displacement location.
- Note: It may be desirable for the regeneration to comprise a centralized facility, or a facility which may benefit from economies of scale, or any combination thereof.

Example 30: CO₂Capture with Decoupled CO₂Absorption or Adsorption, CO₂Desorption or Displacement, and Reagent Regeneration

(1) CO₂Absorption: CO₂absorption in sodium hydroxide solution to produce sodium carbonate solution, or solid precipitate, or any combination thereof.

2NaOH(aq or s)+CO₂(g) custom character Na₂CO₃(aq or s)+H₂O(l or aq or g)

(2) CO₂Desorption or Displacement: Sodium carbonate may be reacted with aqueous sulfurous acid or aqueous sulfur dioxide to produce sodium sulfite and carbon dioxide.

Na₂CO₃(aq or s)+SO₂(aq) custom character Na₂SO₃(aq or s)+CO₂(g)

- Note: SO₂(g) vapor may be present in the CO₂(g). In some embodiments, SO₂(g) may be at least partially removed from CO₂(g) by, for example, including, but not limited to, one or more or any combination of the following: contacting CO₂(g) comprising a portion of SO₂(g) with CaCO₃, or contacting CO₂(g) comprising a portion of SO₂(g) with sodium carbonate, or contacting CO₂(g) comprising a portion of SO₂(g) with an alkali carbonate, or compression, or cooling, or condensing, or cryo-separation, or freeze separation.

(3) Regeneration: Sodium sulfite may be reacted with calcium hydroxide, or calcium oxide, or calcium hydroxide suspension, or any combination thereof to produce sodium hydroxide and calcium sulfite. Calcium sulfite solid is separated from sodium hydroxide solution. Calcium sulfite solid is converted into calcium oxide and sulfur dioxide. Calcium oxide may be reacted with water to produce calcium hydroxide or calcium hydroxide suspension.

Na₂SO₃(aq or s)+Ca(OH)₂(s or aq) custom character CaSO₃(s)+2NaOH(aq or s)
CaSO₃(s)CaO(s)+SO₂(g)
CaO(s)+H₂O(g or l)Ca(OH)₂(s or aq)

Example 31: CO₂Production and Production of Sodium Hydroxide

(1) CO₂Desorption or Displacement: Sodium bicarbonate, which may comprise Nahcolite, may be reacted with aqueous sulfurous acid or aqueous sulfur dioxide to produce sodium sulfite and carbon dioxide.

2NaHCO₃(aq or s)+SO₂(aq) custom character Na₂SO₃(aq or s)+H₂O+2CO₂(g)
Or
2NaHCO₃(aq or s)+2SO₂(aq)NaHSO₃(aq or s)+2CO₂(g)

(2) Production of Sodium Hydroxide: Sodium sulfite may be reacted with calcium hydroxide, or calcium oxide, or calcium hydroxide suspension, or any combination thereof to produce sodium hydroxide and calcium sulfite. Calcium sulfite solid is separated from sodium hydroxide solution. Calcium sulfite solid is converted into calcium oxide and sulfur dioxide. Calcium oxide may be reacted with water to produce calcium hydroxide or calcium hydroxide suspension.

Na₂SO₃(aq or s)+Ca(OH)₂(s or aq) custom character CaSO₃(s)+2NaOH(aq or s)
CaSO₃(s)CaO(s)+SO₂(g)
CaO(s)+H₂O(g or l)Ca(OH)₂(s or aq)

Example 31: CO₂Production and Production of Sodium Hydroxide

(2) CO₂Desorption or Displacement: Sodium bicarbonate, which may comprise Nahcolite, may be reacted with acetic acid to produce sodium acetate and carbon dioxide.

2NaHCO₃(aq or s)+2CH₃COOH custom character 2NaCH₃COO+2CO₂(g)

(3) Regeneration: Sodium acetate may be reacted with sulfur dioxide to produce sodium sulfite and acetic acid. Sodium sulfite is separated from acetic acid. Sodium sulfite may be reacted with calcium hydroxide, or calcium oxide, or calcium hydroxide suspension, or any combination thereof to produce sodium hydroxide and calcium sulfite. Calcium sulfite solid is separated from sodium hydroxide solution. Calcium sulfite solid is converted into calcium oxide and sulfur dioxide. Calcium oxide may be reacted with water to produce calcium hydroxide or calcium hydroxide suspension.

2NaCH₃COO+SO₂(g or aq) custom character Na₂SO₃(aq or s)+2CH₃COOH(aq)
Separate Na₂SO₃and 2CH₃COOH
Na₂SO₃(aq or s)+Ca(OH)₂(s or aq)CaSO₃(s)+2NaOH
CaSO₃(s)CaO(s)+SO₂(g)
CaO(s)+H₂O(g or l)Ca(OH)₂(s or aq)

Example 32: Lithium Hydroxide Production from Lithium Sulfate Using Calcium Precipitation and Acid Intermediate

Note: Residual solids or undissolved solids, such as silicon dioxide or other undissolved solids, may be separated from the liquid solution using a solid-liquid separation.

Ca(CH₃COO)₂(aq)+Li₂SO₄(aq) custom character 2LiCH₃COO(aq)+CaSO₄(s) (2)
2LiCH₃COO(aq)+SO₂(g or aq)+H₂O(l or aq)Li₂SO₃(aq)+2CH₃COOH(aq) (3)
Li₂SO₃(aq)+2CH₃COOH(aq)2CH₃COOH(aq or l)+Li₂SO₃(s)+Water (4)

Note: CH₃COOH may be more soluble in water than Li₂SO₃. In some embodiments, water may be removed and/or Li₂SO₃may be separated or precipitated by, for example, including, but not limited to, evaporation, or distillation, or crystallization, or separation systems or methods described herein, or separation systems or methods described in the art, or any combination thereof.

Note: Li₂SO₃(s) may be separated from CH₃COOH(aq or l) by a solid-liquid separation, which may include, but is not limited to, filter, or centrifuge, or decanter, or separation systems or methods described herein, or separation systems or methods described in the art, or any combination thereof.

Li₂SO₃(s or aq)+Ca(OH)₂(s or aq) custom character 2LiOH(aq or s)+CaSO₃(s) (5)

Note: Ca(OH)₂(s or aq) may comprise a solid-liquid suspension, such as milk of lime.

Note: CaSO₃(s) may be separated using a solid-liquid separation.

CaSO₃(s) custom character CaO(s)+SO₂(g) (6)

Note: ‘(6)’ may comprise calcining CaSO₃(s), which may employ a kiln.

Note: CaSO₃(s) may be dried, or dehydrated, or both before or during ‘(6)’.

CaO(s)+Water(g or l or aq) custom character Ca(OH)₂(s or aq) (7)

Note: CaO(s) may be employed to remove water vapor or facilitated drying of CaSO₃(s) before or during decomposition of CaSO₃(s) to CaO(s).

2LiOH(aq or s) custom character 2LiOH(s)+Water (8)

Note: In some embodiments, water may be removed and/or LiOH may be separated or precipitated by, for example, including, but not limited to, evaporation, or distillation, or crystallization, or separation systems or methods described herein, or separation systems or methods described in the art, or any combination thereof.

Note: In some embodiments, it may be desirable for LiOH to comprise a concentrated aqueous solution.

Example 33: Sodium Hydroxide Production from Sodium Chloride Using Calcium Precipitation, Acid Intermediate, and Process for Producing Sodium Sulfate and Calcium Chloride from Calcium Sulfate and Sodium Chloride

Note: In some embodiments, Na₂SO₄(s or aq) may be transferred from step ‘(10)’.

2NaCH₃COO(aq)+SO₂(g or aq)+H₂O(l or aq) custom character Na₂SO₃(aq)+2CH₃COOH(aq) (3)
Na₂SO₃(aq)+2CH₃COOH(aq)2CH₃COOH(aq or l)+Na₂SO₃(s)+Water (4)

Note: Ca(OH)₂(s or aq) may comprise a solid-liquid suspension, such as milk of lime.

Note: CaSO₃(s) may be separated using a solid-liquid separation.

CaSO₃(s) custom character CaO(s)+SO₂(g) (6)

Note: ‘(6)’ may comprise calcining CaSO₃(s), which may employ a kiln.

Note: CaSO₃(s) may be dried, or dehydrated, or both before or during ‘(6)’.

CaO(s)+Water(g or l or aq) custom character Ca(OH)₂(s or aq) (7)

Note: CaO(s) may be employed to remove water vapor or facilitated drying of CaSO₃(s) before or during decomposition of CaSO₃(s) to CaO(s).

2NaOH(aq or s) custom character 2NaOH(s)+Water (8)

Note: In some embodiments, it may be desirable for NaOH to comprise a concentrated aqueous solution.

CaSO₄(s or aq)+(NH₄)₂CO₃(aq) custom character CaCO₃(s or aq)+(NH₄)₂SO₄(aq) (9)

Note: CaSO₄(s or aq) may be transferred from step ‘(2)’.

Note: CaCO₃(s) may be separated from a solution comprising (NH₄)₂SO₄(aq) by a solid-liquid separation.

(NH₄)₂SO₄(aq)+2NaCl(aq) custom character 2NH₄Cl(aq)+Na₂SO₄(s or aq) (10)

Note: In some embodiments, a portion of Na₂SO₄(s) may be precipitated by cooling precipitation due to, for example, the increasingly lower solubility of Na₂SO₄in water compared to NH₄Cl the lower the temperature below about 32 degrees Celsius or the closer the temperature of the solution is to 0° C.

Note: In some embodiments, Na₂SO₄may be separated from 2NH₄Cl by evaporation, or crystallization, or cooling precipitation, or any combination thereof. In some embodiments, Na₂SO₄(s), or water, or 2NH₄Cl(aq), or 2NH₄Cl(s), or any combination thereof may be produced or may form.

(11) One, or more, or any combination of the following:

2NH₄Cl(s) custom character 2NH₃(g)+2HCl(g)
2NH₃(g)+2HCl(g)+CaCO₃(s)CaCl₂(s)+H₂O(g)+CO₂(g)+2NH₃(g)
CaCO₃(s)+2NH₄Cl(s)CaCl₂(s)+H₂O(g)+CO₂(g)+2NH₃(g)

Note: CaCO₃(s) may be transferred from step ‘(9)’.

Note: One or more or any combination of the above reactions may require heat input.

Note: In some embodiments, heat may be recovered from one or more or any combination of reactions. For example, the calcium carbonate and hydrogen chloride may be exothermic.

Note: In some embodiments, 2NH₄Cl(s) may be precipitated or crystallized from an aqueous solution in the presence of calcium carbonate to, for example, create a distributed mixture of calcium carbonate and ammonium chloride.

Note: Calcium chloride may comprise an output. In some embodiments, calcium chloride may be sold or utilized. In some embodiments, calcium chloride may comprise a waste product.

2NH₃(g)+H₂O(g)+CO₂(g) custom character (NH₄)₂CO₃(s or aq) (12)

Note: (NH₄)₂CO₃(s or aq) may be transferred to step ‘(9)’.

Note: 2NH₃(g), or H₂O(g), or CO₂(g), or any combination thereof may be recycled or recirculated within the process. In some embodiments, losses may occur and/or make up 2 NH₃, or H₂O, or CO₂, or any combination thereof may be added.

Example 34: Process for Producing Sodium Sulfate, Ammonia, and Calcium Chloride from Ammonium Sulfate, Sodium Chloride, and Calcium-Weak Acid

(NH₄)₂SO₄(aq)+2NaCl(aq) custom character 2NH₄Cl(aq)+Na₂SO₄(s or aq) (1)

(2) One, or more, or any combination of the following:

2NH₄Cl(s) custom character 2NH₃(g)+2HCl(g)
2NH₃(g)+2HCl(g)+CaCO₃(s)CaCl₂(s)+H₂O(g)+CO₂(g)+2NH₃(g)
CaCO₃(s)+2NH₄Cl(s)CaCl₂(s)+H₂O(g)+CO₂(g)+2NH₃(g)
2NH₃(g)+2HCl(g)+Ca(WA)(s)CaCl₂(s)+H₂O(g)+WA(s or g or l)+2NH₃(g)
Ca(WA)(s)+2NH₄Cl(s)CaCl₂(s)+H₂O(g)+WA(s or g or l)+2NH₃(g)

Note: One or more or any combination of the above reactions may require heat input.

Note: In some embodiments, heat may be recovered from one or more or any combination of reactions. For example, the calcium carbonate and hydrogen chloride may be exothermic.

Note: In some embodiments, 2NH₄Cl(s) may be precipitated or crystallized from an aqueous solution in the presence of calcium-weak acid to, for example, create a distributed mixture of calcium-weak acid and ammonium chloride.

Note: Calcium chloride may comprise an output. In some embodiments, calcium chloride may be sold or utilized. In some embodiments, calcium chloride may comprise a waste product.

Note: In some embodiments, carbon dioxide produced may comprise captured carbon dioxide. For example, ammonia and/or water may be separated from carbon dioxide using an aqueous solution and/or high pressures and/or elevated temperatures.

Example 35: Process for Producing Sodium Sulfate and Calcium Chloride from Sodium Chloride and Calcium Sulfate Using an Ammonia and Carbon Dioxide Intermediate

CaSO₄(s or aq)+(NH₄)₂CO₃(aq) custom character CaCO₃(s or aq)+(NH₄)₂SO₄(aq) (1)

Note: CaSO₄(s or aq) may comprise an input. For example, CaSO₄(s) may be a product or byproduct from a process. For example, CaSO₄(s) may be mined. For example, CaSO₄(s) may comprise phosphogypsum.

Note: CaCO₃(s) may be separated from a solution comprising (NH₄)₂SO₄(aq) by a solid-liquid separation.

(NH₄)₂SO₄(aq)+2NaCl(aq) custom character 2NH₄Cl(aq)+Na₂SO₄(s or aq) (2)

Note: In some embodiments, Na₂SO₄may be separated from 2NH₄Cl by evaporation, or crystallization, or cooling precipitation, or separation method described herein, or any combination thereof. In some embodiments, Na₂SO₄(s), or water, or 2NH₄Cl(aq), or 2NH₄Cl(s), or any combination thereof may be produced or may form.

(3) One, or more, or any combination of the following:

2NH₄Cl(s) custom character 2NH₃(g)+2HCl(g)
2NH₃(g)+2HCl(g)+CaCO₃(s)CaCl₂(s)+H₂O(g)+CO₂(g)+2NH₃(g)
CaCO₃(s)+2NH₄Cl(s)CaCl₂(s)+H₂O(g)+CO₂(g)+2NH₃(g)

Note: CaCO₃(s) may be transferred from step ‘(1)’.

Note: One or more or any combination of the above reactions may require heat input.

Note: In some embodiments, heat may be recovered from one or more or any combination of reactions. For example, the calcium carbonate and hydrogen chloride may be exothermic.

Note: (NH₄)₂CO₃(s or aq) may be transferred to step ‘(1)’.

Example 36: Process for Producing Sodium Sulfate and Calcium Chloride from Sodium Chloride and Calcium Sulfate while Capturing Carbon Dioxide

2NH₃(aq)+H₂O(g)+CO₂(g) custom character (NH₄)₂CO₃(s or aq) (1)

Note: CO₂(g) may comprise a gas comprising CO₂(g). In some embodiments, the CO₂(g) may comprise a gas comprising a dilute concentration of carbon dioxide, which may include, but is not limited to, flue gas, or emissions gas, or sour gas, or air, or other CO₂sources described herein, or other CO₂sources in the art, or any combination thereof.

CaSO₄(s or aq)+(NH₄)₂CO₃(aq) custom character CaCO₃(s or aq)+(NH₄)₂SO₄(aq) (2)

Note: CaCO₃(s) may be separated from a solution comprising (NH₄)₂SO₄(aq) by a solid-liquid separation.

(NH₄)₂SO₄(aq)+2NaCl(aq) custom character 2NH₄Cl(aq)+Na₂SO₄(s or aq) (3)

(4) One, or more, or any combination of the following:

2NH₄Cl(s) custom character 2NH₃(g)+2HCl(g)
2NH₃(g)+2HCl(g)+CaCO₃(s)CaCl₂(s)+H₂O(g)+CO₂(g)+2NH₃(g)
CaCO₃(s)+2NH₄Cl(s)CaCl₂(s)+H₂O(g)+CO₂(g)+2NH₃(g)

Note: CaCO₃(s) may be transferred from step ‘(1)’.

Note: One or more or any combination of the above reactions may require heat input.

Note: In some embodiments, heat may be recovered from one or more or any combination of reactions. For example, the calcium carbonate and hydrogen chloride may be exothermic.

Note: 2NH₃(aq) may be transferred to step ‘(1)’.

Note: If conducted at a pressure greater than 0.9 atm, or 1 atm, or 1.2 atm, or 1.4 atm, or 1.6 atm, or 1.8 atm, or 2 atm, or 2.5 atm, or 3 atm, or 4 atm, or 5 atm, or any combination thereof and/or temperature greater than 50° C., 60° C., or 70° C., or 80° C., or 90° C., or 100° C., or 110° C., or 120° C., or 130° C. or any combination thereof in the presence of liquid water, ammonia may mostly transfer to the aqueous phase, while carbon dioxide may mostly remain at a gas phase.

Note: In some embodiments, CO₂may be further purified to remove residual ammonia. For example, CO₂(g) comprising residual ammonia may be cooled, which may result in the removal of at least a portion of the residual ammonia by the formation of ammonia-carbon dioxide derivative salts, such as ammonium carbamate, or ammonium carbonate, or ammonium bicarbonate, or any combination thereof. For example, CO₂(g) comprising residual ammonia may be cooled and/or contacted with water, which may result in the removal of at least a portion of the residual ammonia by the formation of aqueous ammonia, or ammonia-carbon dioxide derivative salts, such as ammonium carbamate, or ammonium carbonate, or ammonium bicarbonate, or any combination thereof.

Example 37: Process for Producing Sodium Sulfate, Calcium Chloride, and Urea from Sodium Chloride, Calcium Sulfate, Ammonia, and Carbon Dioxide

2NH₃(g or aq)+Water+CO₂(g) custom character (NH₄)₂CO₃(s or aq) (1)

Note: CaCO₃(s) may be separated from a solution comprising (NH₄)₂SO₄(aq) by a solid-liquid separation.

(NH₄)₂SO₄(aq)+2NaCl(aq) custom character 2NH₄Cl(aq)+Na₂SO₄(s or aq) (3)

Note: CaCO₃(s) may be transferred from step ‘(1)’.

Note: One or more or any combination of the above reactions may require heat input.

Note: In some embodiments, heat may be recovered from one or more or any combination of reactions. For example, the calcium carbonate and hydrogen chloride may be exothermic.

Note: The process may produce urea and/or water.

Note: It may be desirable to further dry the ammonia, or carbon dioxide, or both before use in the production of urea.

Example 38: Sodium Hydroxide Production from Sodium Sulfate Using Calcium Precipitation and Acid Intermediate

Note: An aqueous solution comprising sodium sulfite and acetic acid may be separated into a separate aqueous solution comprising acetic acid and a separate aqueous solution comprising sodium sulfite using, for example, electrodialysis, or electrodialysis reversal, or selective electrodialysis.

Note: For example, some embodiments may employ electrodialysis selective for monovalent or divalent or trivalent or tetravalent cations, or monovalent or divalent or trivalent or tetravalent anions, or any combination thereof.

Note: The aqueous solution comprising acetic acid may be employed as the aqueous acetic acid in step ‘(1)’.

Na₂SO₃(aq)+Ca(OH)₂(s or aq) custom character 2NaOH(aq)+CaSO₃(s) (5)

Note: Ca(OH)₂(s or aq) may comprise a solid-liquid suspension, such as milk of lime.

Note: CaSO₃(s) may be separated using a solid-liquid separation.

CaSO₃(s) custom character CaO(s)+SO₂(g) (6)

Note: ‘(6)’ may comprise calcining CaSO₃(s), which may employ a kiln.

Note: CaSO₃(s) may be dried, or dehydrated, or both before or during ‘(6)’.

CaO(s)+Water(g or l or aq) custom character Ca(OH)₂(s or aq) (7)

Note: CaO(s) may be employed to remove water vapor or facilitated drying of CaSO₃(s) before or during decomposition of CaSO₃(s) to CaO(s).

2NaOH(aq) custom character 2NaOH(aq or s)+Water (8)

Note: In some embodiments, it may be desirable for NaOH to comprise an aqueous solution or concentrated aqueous solution. In some embodiments, NaOH(aq) may be concentrated or further concentration using one or more or any combination of separation methods or water removal methods.

Note: Water or distillate from concentrating or further concentrating may be employed within the process. For example, water or distillate from concentrating or further concentrating may be employed to, for example, including but not limited to, one or more or any combination of the following: to dissolve sodium sulfate, or to absorb acetic acid vapor, or dilute or mix with the aqueous solution comprising sodium acetate, or dilute or mix with the aqueous solution comprising sodium sulfite and acetic acid, or any combination thereof.

Example 39: Sodium Hydroxide and Calcium Oxide Production from Sodium Sulfate and Calcium Carbonate Using Calcium Precipitation and Acid Intermediate

Note: In some embodiments, may be conducted under high CO₂partial pressures and/or elevated temperatures. For example, some embodiments may employ CO₂partial pressures greater than 1 Bar, or 2 Bar, or 3 Bar, or 4 Bar, or 5 Bar, or any combination thereof and/or temperatures greater than 0° C., or 20° C., or 40° C., or 50° C., or 60° C., or 70° C., or 80° C., or 90° C., or 95° C., or 100° C.

Note: CO₂may be sourced from, including, but not limited to, one or more or any combination of the following: the decomposition of sodium bicarbonate, or captured carbon dioxide, or any combination thereof.

Na₂SO₃(s)+Water custom character Na₂SO₃(aq) (6)
Na₂SO₃(aq)+Ca(HCO₃)₂(aq)2NaHCO₃(aq)+CaSO₃(s) (7)
CaSO₃(s)CaO(s)+SO₂(g) (8)
2NaHCO₃(aq)Na₂CO₃(aq)+CO₂(g)+H₂O(g or l) (9)
Na₂CO₃(aq)+Ca(OH)₂(s or aq)2NaOH(aq)+CaCO₃(s) (10)
2NaOH(aq)2NaOH(aq or s)+Water (11)
CaCO₃(s) custom character CaO(s)+CO₂(g) (12)

Note: In some embodiments, calcium carbonate may be decomposed into calcium oxide in a manner which produces high purity or captured carbon dioxide. For example, in some embodiments, calcium carbonate may be calcined or decomposed by indirect calcination or indirect heating, which may result in the production of high purity or captured carbon dioxide.

Note: Captured carbon dioxide may be sequestered or employed in one or more or any combination of applications.

CaO(s)+Water custom character Ca(OH)₂(s or aq) (13)

Note: In some embodiments, calcium oxide may be reacted directly with an aqueous solution comprising sodium carbonate to produce calcium carbonate and sodium hydroxide. For example, in some embodiments, step ‘(10)’ may be combined with step ‘(13)’.

Example 40: Sodium Carbonate, or Sodium Bicarbonate Production from Sodium Sulfate Using Calcium Precipitation and Acid Intermediate

Example 41: Sodium Hydroxide Production from Sodium Sulfate Using Calcium Precipitation, Acid Intermediate, and Calcium Carbonate Intermediate

Note: In some embodiments, may be conducted under high CO₂partial pressures and/or elevated temperatures. For example, some embodiments may employ CO₂partial pressures greater than 1 Bar, or 2 Bar, or 3 Bar, or 4 Bar, or 5 Bar, or 6 Bar, or 7 Bar, or 8 Bar, or 9 Bar, or 10 Bar, or 11 Bar, or 12 Bar, or 13 Bar, or 14 Bar, or 15 Bar, or any combination thereof and/or temperatures greater than 0° C., or 20° C., or 40° C., or 50° C., or 60° C., or 70° C., or 80° C., or 90° C., or 95° C., or 100° C.

Note: CaO(s) may be transferred to step ‘(9)’ or step ‘(11).’

Note: SO₂(g) may be transferred to step ‘(3).’

CaO(s)+Water custom character Ca(OH)₂(s or aq) (9)

Note: In some embodiments, calcium oxide may be reacted directly with an aqueous solution comprising sodium carbonate to produce calcium carbonate and sodium hydroxide. In some embodiments, calcium oxide may be reacted directly with an aqueous solution comprising sodium carbonate to produce calcium carbonate and sodium hydroxide, which may comprise combining step ‘(9)’ and step ‘(11).’

2NaHCO₃(aq) custom character Na₂CO₃(aq)+CO₂(g)+H₂O(g or l) (10)

Note: CO₂may be transferred to step ‘(5)’.

Na₂CO₃(aq)+Ca(OH)₂(s or aq) custom character 2NaOH(aq)+CaCO₃(s) (11)

Note: An aqueous solution comprising sodium hydroxide may be separated from calcium carbonate by a solid-liquid separation.

Note: Calcium carbonate may be transferred to ‘(5)’.

2NaOH(aq) custom character 2NaOH(aq or s)+Water (12)

Note: The solution comprising sodium hydroxide may be further concentrated, or at least a portion of water may be removed from the solution comprising sodium hydroxide, or any combination thereof.

Note: In some embodiments, at least a portion of the water removed or recovered from the solution comprising aqueous sodium hydroxide may be transferred to step ‘(6)’.

Example 42: Sodium Hydroxide Production from Sodium Sulfate and Calcium Carbonate Using Calcium Precipitation and Carbon Dioxide Intermediate

CaCO₃(s or aq)+CO₂(g or aq)+H₂O(aq) custom character Ca(HCO₃)₂(aq) (1)

Note: In some embodiments, may be conducted under high CO₂partial pressures and/or elevated temperatures. For example, some embodiments may employ CO₂partial pressures greater than 1 Bar, or 2 Bar, or 3 Bar, or 4 Bar, or 5 Bar, or 6 Bar, or 7 Bar, or 8 Bar, or 9 Bar, or 10 Bar, or 11 Bar, or 12 Bar, or 13 Bar, or 14 Bar, or 15 Bar, or any combination thereof and/or temperatures greater than 0° C., or 20° C., or 40° C., or 50° C., or 60° C., or 70° C., or 80° C., or 90° C., or 95° C., or 100° C.

Note: CO₂may be transferred to step ‘(1)’.

Na₂CO₃(aq)+Ca(OH)₂(s or aq) custom character 2NaOH(aq)+CaCO₃(s) (4)

Note: An aqueous solution comprising sodium hydroxide may be separated from calcium carbonate by a solid-liquid separation.

Note: Calcium carbonate may be transferred to ‘(5)’.

2NaOH(aq) custom character 2NaOH(aq or s)+Water (5)

Note: The solution comprising sodium hydroxide may be further concentrated, or at least a portion of water may be removed from the solution comprising sodium hydroxide, or any combination thereof.

Note: In some embodiments, at least a portion of the water removed or recovered from the solution comprising aqueous sodium hydroxide may be transferred to step ‘(1)’ or step ‘(2)’.

CaCO₃(s) custom character CaO(s)+CO₂(g) (6)

Note: Captured carbon dioxide may be sequestered or employed in one or more or any combination of applications.

CaO(s)+Water custom character Ca(OH)₂(s or aq) (7)

Example 43: Sodium Carbonate or Sodium Bicarbonate Production from Sodium Sulfate and Calcium Carbonate

CaCO₃(s or aq)+CO₂(g or aq)+H₂O(aq) custom character Ca(HCO₃)₂(aq) (1)

Note: In some embodiments, may be conducted under high CO₂partial pressures and/or elevated temperatures. For example, some embodiments may employ CO₂partial pressures greater than 1 Bar, or 2 Bar, or 3 Bar, or 4 Bar, or 5 Bar, or 6 Bar, or 7 Bar, or 8 Bar, or 9 Bar, or 10 Bar, or 11 Bar, or 12 Bar, or 13 Bar, or 14 Bar, or 15 Bar, or any combination thereof and/or temperatures greater than 0° C., or 20° C., or 40° C., or 50° C., or 60° C., or 70° C., or 80° C., or 90° C., or 95° C., or 100° C.

Note: In some embodiments, NaHCO₃(aq) or NaHCO₃(s) may comprise a product which may be sold or utilized.

Note: 2NaHCO₃(aq) may be separated from at least a portion of CaSO₄(s) by solid-liquid separation.

2NaHCO₃(aq) custom character Na₂CO₃(aq)+CO₂(g)+H₂O(g or l) (3)

Note: CO₂may be transferred to step ‘(1)’.

Example 44: Process for Producing Sodium Hydroxide and Calcium Sulfate from Sodium Sulfate and Calcium Weak Acid

Note: Residual solids or undissolved solids, such as silicon dioxide or other undissolved solids, may be separated from the liquid solution using a solid-liquid separation.

Note: CO₂(g) may comprise captured CO₂.

Note: In some embodiments, some chemicals comprising calcium may comprise a portion of magnesium. In some embodiments, for example, input chemicals or input material may comprise a mixture of calcium and magnesium.

Ca(CH₃COO)₂(aq)+SO₂(g or aq)+H₂O(l or aq) custom character CaSO₃(s)+2CH₃COOH(aq) (2)

Note: CaSO₃(s) may be separated using a solid-liquid separation.

Note: In some embodiments, residual aqueous magnesium sulfite may be present in the ‘2CH₃COOH(aq)’. In some embodiments, the residual aqueous magnesium sulfite may remain in the ‘2CH₃COOH(aq)’ transferred to reaction ‘(1)’ from reaction’. In some embodiments, the aqueous magnesium sulfite may remain in the ‘2CH₃COOH(aq)’ transferred to reaction ‘(1)‘ from reaction’(2)’ because, for example, magnesium sulfite additional or accumulated magnesium sulfite above the solubility limits of magnesium sulfite in the solution may precipitate or co-precipitate during the reaction of Ca(CH₃COO)₂(aq) or Mg(CH₃COO)₂(aq) with SO₂(g or aq) or sulfite or bisulfite.

Note: ‘(4)’ may be conducted at an elevated temperature to reduce the solubility or dissolution of CaSO₄(s) or reduce potential formation of CaSO₄(aq).

(5) One or more or any combination of the following:

2NaHSO₃(aq) custom character Na₂SO₃(s or aq)+SO₂(g)+H₂O(g or l)
2NaHSO₃(aq)Na₂S₂O₅(s)+H₂O+Water
Na₂S₂O₅(s)Na₂SO₃(s)+SO₂(g)
SO₂(g or aq)+WaterSO₂(aq) (6)
Na₂SO₃(s or aq)+Ca(OH)₂(s or aq)2NaOH(aq)+CaSO₃(s) (7)
CaSO₃(s)CaO(s)+SO₂(g) (8)
CaO(s)+H₂O+Water custom character Ca(OH)₂(s or aq) (9)

Example 45: Sodium Hydroxide Production from Sodium Sulfate Using Calcium Precipitation and Acid Intermediates

Note: Residual solids or undissolved solids, such as silicon dioxide or other undissolved solids, may be separated from the liquid solution using a solid-liquid separation.

Ca(CH₃COO)₂(aq)+Na₂SO₄(aq) custom character 2NaCH₃COO(aq)+CaSO₄(s) (2)
2NaCH₃COO(aq)+Citric Acid(aq)Sodium Citrate(aq)+2CH₃COOH(aq) (3)

Note: In some embodiments, other carboxylic acids than citric acid may be employed, such as carboxylic acids which form soluble sodium salts and relatively low solubility calcium salts.

Sodium Citrate(aq)+2CH₃COOH(aq) custom character Sodium Citrate(s)+2CH₃COOH(aq) (4)

Note: ‘(4)’ may comprise separating sodium citrate from acetic acid. For example, sodium citrate may be separated from an aqueous solution comprising acetic acid or from acetic acid by distillation.

Sodium Citrate(aq)+Ca(OH)₂(s or aq) custom character Calcium Citrate(s)+2NaOH(aq) (5)

Note: Aqueous solution comprising sodium hydroxide may be separated from a solid comprising calcium citrate by a solid-liquid separation.

2NaOH(aq) custom character 2NaOH(aq or s)+Water (6)

Note: In some embodiments, an aqueous solution comprising sodium hydroxide may be further concentrated, or water may be removed from the solution comprising sodium hydroxide, or any combination thereof. In some embodiments, the aqueous solution comprising sodium hydroxide may undergo further treatment. In some embodiments, the aqueous solution comprising sodium hydroxide may comprise a product and/or may be ready to be sold or utilized.

Calcium Citrate(s)+SO₂(aq) custom character Citric Acid(aq)+CaSO₃(s) (7)
CaSO₃(s)CaO(s)+SO₂(g) (8)
SO₂(g)+WaterSO₂(aq) (9)
CaO(s)+H₂O+WaterCa(OH)₂(s or aq) (10)

Note: In some embodiments, CaO(s) may be reacted with water. In some embodiments, CaO(s) may be reacted with Sodium Citrate to produce Calcium Citrate and Sodium Hydroxide. In some embodiments, for example, step ‘(5)’ and step ‘(10)’ may be combined.

Example 46: Process for Producing Calcium Oxide or Cement or Clinker with Ascorbic Acid Intermediate

(1) React Material comprising Calcium, or Magnesium, or Other Alkaline Earth-Weak Acid Anion with Ascorbic Acid, which may comprise, including, but not limited to, one or more or any combination of the following:

CaCO₃(s or aq)+Ascorbic Acid(aq) custom character Calcium Ascorbate(aq)+CO₂(g)
Calcium Silicate(s)+Ascorbic Acid(aq)Calcium Ascorbate(aq)+Silicon Dioxide(s)
CaS(s)+Ascorbic Acid(aq)Calcium Ascorbate(aq)+H₂S(g)
Calcium(Weak Acid Anion)+Ascorbic Acid(aq)Calcium Ascorbate(aq)+Weak Acid(s, or g, or l, or aq)

Note: Residual solids or undissolved solids, such as silicon dioxide or other undissolved solids, may be separated from the liquid solution using a solid-liquid separation.

Note: CO₂(g) may comprise captured CO₂.

Note: In some embodiments, some chemicals comprising calcium may comprise a portion of magnesium. In some embodiments, for example, input chemicals or input material may comprise a mixture of calcium and magnesium.

Calcium Ascorbate(aq)+SO₂(g or aq)+H₂O(l or aq) custom character CaSO₃(s)+Ascorbic Acid(aq) (2)

Note: CaSO₃(s) may be separated using a solid-liquid separation.

Note: In some embodiments, residual aqueous magnesium sulfite may be present in the ‘2CH₃COOH(aq)’. In some embodiments, the residual aqueous magnesium sulfite may remain in the ‘2CH₃COOH(aq)’ transferred to reaction ‘(1)’ from reaction’. In some embodiments, the aqueous magnesium sulfite may remain in the ‘2CH₃COOH(aq)’ transferred to reaction ‘(1)‘ from reaction’(2)’ because, for example, magnesium sulfite additional or accumulated magnesium sulfite above the solubility limits of magnesium sulfite in the solution may precipitate or co-precipitate during the reaction of Ca(CH₃COO)₂(aq) or Mg(CH₃COO)₂(aq) with SO₂(g or aq) or sulfite or bisulfite.

Note: In some embodiments, the use of ascorbic acid may be desirable because ascorbic acid may be non-volatile, or may comprise minimal or no vapor phase, or any combination thereof, which may mean ascorbic acid may substantially remain at an aqueous phase, or ascorbic acid may substantially not evaporate into remaining gases, or any combination thereof. In some embodiments, other acids with stronger acid strength than a ‘WA’ or ‘Weak Acid’ and weaker acidity than sulfurous acid, or which form water soluble calcium or magnesium or alkaline earth salts, or which are non-volatile or have a lower vapor pressure or higher boiling point than water, or any combination thereof may be employed instead of, or in addition to, ascorbic acid.

CaSO₃(s) custom character CaO(s)+SO₂(g) (3)

Note: ‘(3)’ may comprise calcining CaSO₃(s), which may employ a kiln.

Note: CaSO₃(s) may be dried, or dehydrated, or both before or during ‘(3)’.

Example 47: Sodium Hydroxide Production from Sodium Sulfate with Calcium Precipitation and Acid Intermediate

Note: In some embodiments, the present reaction may be conducted at an elevated temperature or temperature greater than 100° C., or 200° C., or 300° C., or 400° C., or 500° C., or 600° C., or any combination thereof.

Example 48: Sodium Carbonate Production from Sodium Sulfate with Calcium Precipitation and Acid Intermediate

Example 49: Process for Direct Air Capture with Alkali Intermediate

(1) One or more or any combination of the following:

CaO(s or aq)+CO₂(g or aq) custom character CaCO₃(s or aq)
Ca(OH)₂(s or aq)+CO₂(g or aq)CaCO₃(s or aq)+H₂O(aq)

Note: If CO₂(g) is produced, it may be desirable for said CO₂(g) to be produced at a high partial pressure CO₂(g), or purity CO₂(g), or to comprise captured CO₂(g).

CaCO₃(s or aq)+2CH₃COOH(aq) custom character Ca(CH₃COO)₂(aq)+CO₂(g) (2)

Note: It may be desirable for the CO₂(g) to be produced at a high partial pressure CO₂(g), or purity CO₂(g), or to comprise captured CO₂(g).

Ca(CH₃COO)₂(aq)+Na₂SO₃(s or aq) custom character 2NaCH₃COO(aq)+CaSO₃(s) (3)

Note: CaSO₃(s) may be separated using a solid-liquid separation.

2NaCH₃COO(aq)+SO₂(g or aq)+H₂O(l or aq) custom character Na₂SO₃(aq)+2CH₃COOH(aq) (4)
Na₂SO₃(aq)+2CH₃COOH(aq)2CH₃COOH(aq)+Na₂SO₃(s) (5)
CaSO₃(s)CaO(s)+SO₂(g) (6)
CaO(s)+WaterCa(OH)₂(s or aq) (7)

Example 50: Process for Producing Precipitated Calcium Carbonate

(4) One or more or any combination of the following:

CaO(s)+CO₂ custom character CaCO₃(s)
CaO(s)+WaterCa(OH)₂(s or aq)
Ca(OH)₂(s or aq)+CO₂CaCO₃(s or aq)

Example 51: Sodium Hydroxide Production and Precipitated Calcium Carbonate Production from Sodium Bicarbonate Using Calcium Precipitation and Acid Intermediate

Note: Residual solids or undissolved solids, such as silicon dioxide or other undissolved solids, may be separated from the liquid solution using a solid-liquid separation.

Note: CO₂(g) may comprise captured CO₂.

Note: In some embodiments, acetic acid vapor and/or water vapor may be separated or recovered from CO₂(g).

Ca(CH₃COO)₂(aq)+2NaHCO₃(aq or s) custom character 2NaCH₃COO(aq)+CaCO₃(s)+CO₂(g) (2)

Note: In some embodiments, NaHCO₃(s) may be added directly to or dissolved in Ca(CH₃COO)₂(aq).

Note: In some embodiments, NaHCO₃(aq or s) may comprise a mineral, or may comprise nahcolite, or any combination thereof.

Note: In some embodiments, NaHCO₃(s) may be dissolved in water or an aqueous solution to form NaHCO₃(aq) before mixing with Ca(CH₃COO)₂(aq).

Note: The CO₂(g) may comprise captured CO₂(g).

Note: Some embodiments may form dissolved calcium bicarbonate. In some embodiments, dissolved calcium bicarbonate may be decomposed into calcium carbonate and carbon dioxide may heating solution, or depressurizing the solution, or any combination thereof.

Note: CaCO₃(s) may comprise precipitated calcium carbonate.

Note: CaCO₃(s) may be separated by solid-liquid separation.

2NaCH₃COO(aq)+SO₂(g or aq)+H₂O(l or aq) custom character Na₂SO₃(aq)+2CH₃COOH(aq) (3)

Note: Ca(OH)₂(s or aq) may comprise a solid-liquid suspension, such as milk of lime.

Note: CaSO₃(s) may be separated using a solid-liquid separation.

CaSO₃(s) custom character CaO(s)+SO₂(g) (6)

Note: ‘(6)’ may comprise calcining CaSO₃(s), which may employ a kiln.

Note: CaSO₃(s) may be dried, or dehydrated, or both before or during ‘(6)’.

CaO(s)+Water(g or l or aq) custom character Ca(OH)₂(s or aq) (7)

Note: In some embodiments, CaO(s) may be employed to remove water vapor or facilitated drying of CaSO₃(s) before or during decomposition of CaSO₃(s) to CaO(s).

Note: In some embodiments, NaOH(aq) may be concentrated into an aqueous solution comprising a greater mass percent concentration of NaOH.

Note: In some embodiments, it may be desirable for NaOH to comprise a concentrated aqueous solution

Example 52: Sodium Hydroxide Production and Precipitated Calcium Carbonate Production from Sodium Carbonate Using Calcium Precipitation and Acid Intermediate

Note: Residual solids or undissolved solids, such as silicon dioxide or other undissolved solids, may be separated from the liquid solution using a solid-liquid separation.

Note: CO₂(g) may comprise captured CO₂.

Note: In some embodiments, acetic acid vapor and/or water vapor may be separated or recovered from CO₂(g).

Ca(CH₃COO)₂(aq)+Na₂CO₃(aq or s) custom character 2NaCH₃COO(aq)+CaCO₃(s) (2)

Note: In some embodiments, Na₂CO₃(aq or s) may be added directly to or dissolved in Ca(CH₃COO)₂(aq).

Note: In some embodiments, Na₂CO₃(aq or s) may comprise a mineral, or may comprise decomposed nahcolite, or any combination thereof.

Note: In some embodiments, Na₂CO₃(aq or s) may be dissolved in water or an aqueous solution to form NaHCO₃(aq) before mixing with Ca(CH₃COO)₂(aq).