Claims
- 1. An adsorption process for separating citric acid from a fermentation broth feed mixture comprising contacting said mixture with a water-insoluble, macroreticular or gel, weakly basic anionic exchange resin possessing tertiary amine or pyridine functional groups, said weakly basic anionic exchange resin having a crosslinked acrylic or styrene resin matrix at adsorption conditions selected to selectively adsorb said citric acid, desorbing said citric acid with a desorbent comprising water or a dilute inorganic acid at desorption conditions, said adsorption conditions including pH lower than the first ionization constant (pKa.sub.1) of citric acid.
- 2. The process of claim 1 further characterized in that said adsorption and desorption conditions include a temperature within the range of from about 20.degree. C. to about 200.degree. C. and a pressure within the range of from about atmospheric to about 500 psig (3450 kPa gauge).
- 3. The process of claim 1 further characterized in that the pH of said feed mixture is lower than the first ionization constant (PKa.sub.1) of citric acid.
- 4. The process of claim 1 further characterized in that said adsorbent has a tertiary amine functional group and said matrix is a cross-linked acrylic resin.
- 5. The process of claim 1 further characterized in that said adsorbent has a pyridine functional group and said matrix is a cross-linked polystyrene resin.
- 6. The process of claim 5 further characterized in that said adsorbent has a surface area of at least 10 m.sup.2 /g.
- 7. The process of claim 1 wherein said fermentation broth comprises citric acid, carbohydrates, protein, amino acid and salts.
- 8. The process of claim 1 wherein said desorbent is sulfuric acid at a concentration in the range from about 0.01N to about 1N.
- 9. A process for separating citric acid from a feed mixture comprising a fermentation broth, which process employs a water-insoluble, macroreticular or gel, weakly basic anionic exchange resin adsorbent possessing tertiary amine functional groups or pyridine functional groups, said anionic exchange resin having a crosslinked acrylic or styrene resin matrix which process comprises the steps of:
- (a) maintaining net fluid flow through a column of said adsorbent in a single direction, which column contains at least three zones having separate operational functions occurring therein and being serially interconnected with the terminal zones of said column connected to provide a continuous connection of said zones;
- (b) maintaining an adsorption zone in said column, said zone defined by the adsorbent located between a feed input stream at an upstream boundary of said zone and a raffinate output stream at a downstream boundary of said zone;
- (c) maintaining a purification zone immediately upstream from said adsorption zone, said purification zone defined by the adsorbent located between an extract output stream at an upstream boundary of said purification zone and said feed input stream at a downstream boundary of said purification zone;
- (d) maintaining a desorption zone immediately upstream from said purification zone, said desorption zone defined by the adsorbent located between a desorbent input stream at an upstream boundary of said zone and said extract output stream at a downstream boundary of said zone;
- (e) passing said feed mixture into said adsorption zone at adsorption conditions to effect the selective adsorption of said citric acid by said adsorbent in said adsorption zone and withdrawing a raffinate output stream comprising the nonadsorbed components of said fermentation broth from said adsorption zone;
- (f) passing a desorbent material comprising water or a dilute inorganic acid into said desorption zone at desorption conditions to effect the displacement of said citric acid from the adsorbent in said desorption zone;
- (g) withdrawing an extract output stream comprising said citric acid and desorbent material from said desorption zone;
- (h) passing at least a portion of said extract output stream to a separation means and therein separating at separation conditions at least a portion of said desorbent material; and,
- (i) periodically advancing through said column of adsorbent in a downstream direction with respect to fluid flow in said adsorption zone the feed input stream, raffinate output stream, desorbent input stream, and extract output stream to effect the shifting of zones through sid adsorbent and the production of extract output and raffinate output streams.
- 10. The process of claim 9 further characterized in that it includes the step of passing at least a portion of said extract output stream to a separation means and therein separating at separation conditions at least a portion of said desorbent material to produce an extract product having a reduced concentration of desorbent material.
- 11. The process of claim 9 further characterized in that it includes the step of maintaining a buffer zone immediately upstream from said desorption zone, said buffer zone defined as the adsorbent located between the desorbent input stream at a downstream boundary of said buffer zone and the raffinate output stream at an upstream boundary of said buffer zone.
- 12. The process of claim 9 further characterized in that said adsorption conditions and desorption conditions include a temperature within the range of from about 20.degree. C. to about 200.degree. C. and a pressure within the range of from about atmospheric to about 500 psig (3450 kPa gauge) to ensure liquid phase.
- 13. The process of claim 9 wherein said desorbent is sulfuric acid at a concentration in the range from about 0.01N to about 1N.
- 14. The process of claim 9 further characterized in that the pH of said feed mixture is lower than the first ionization constant (pKa.sub.1) of citric acid.
- 15. The process of claim 9 wherein the pH of the said feed mixture is below 3.13.
- 16. The process of claim 9 wherein said fermentation broth comprises citric acid, carbohydrates and salts.
- 17. The process of claim 16 wherein said fermentation broth additionally contains proteins and amino acids.
- 18. The process of claim 1 wherein said desorbent is a dilute sulfuric acid.
- 19. The process of claim 18 wherein the concentration of said sulfuric acid is from 0.01N to 1.0N.
- 20. The process of claim 18 wherein the concentration of said sulfuric acid is from 0.05N to 0.25N.
- 21. The process of claim 1 wherein said adsorbent is in the sulfate form.
CROSS-REFERENCE TO RELATED APPLICATIONS
This is a continuation in part of Ser. No. 943,219, filed Dec. 18, 1986. A related case, filed concurrently herewith, Ser. No. Ser. No. 122,161, filed Nov. 16, 1987 is also a continuation-in-part of said Ser. No. 943,219.
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
4323702 |
Kowabata et al. |
Apr 1982 |
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Foreign Referenced Citations (1)
Number |
Date |
Country |
868926 |
Jun 1957 |
GBX |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
943219 |
Dec 1986 |
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