Patent Grant
8968576
Not applicable
Not applicable
1. Field of the Invention
This invention relates to a method of oxidatively treating gases, liquids, slurries and surfaces in which high energy oxidants are created through the nebulization of an oxidizer into an energy field. If the media requiring treatment may itself be nebulized, treatment will occur within the radiation/energy field. If the media requiring treatment is a surface or bulk slurry, the energy field is positioned directly above but not on the surface requiring treatment. This oxidation method may be employed for disinfection, purification, sterilization, destruction of organic molecules, oxidation of inorganics, oxidation of metals, and co-precipitation of metals.
2. General Background of the Invention
Free radical formation is a process that has been developed for the purification and disinfection of contaminated liquids, gases, and surfaces. The present invention is an efficient method of free radical application through instantaneous formation of free radicals through the nebulization of liquid and gas oxidants through an energy field.
The process of nebulization or atomization has per se been used in prior art for the dispersion of powders or liquids into clouds (U.S. Pat. No. 4,993,411), humidification of air or oxygen gas for inhalation (U.S. Pat. Nos. 6,511,050; 5,407,604; 4,993,411) the dispersion of fuel into a cloud for efficient combustion (U.S. Pat. Nos. 4,696,719; 4,267,976), and the saturation of a liquid with oxygen, ozone or other gas (U.S. Pat. No. 5,366,696). The dispersion of liquids, slurries or solids into nano-sized droplets or particles increases the effective surface area available for instantaneous reaction and therefore increases efficiency of processes.
Prior art nebulizers which can be used in this process include two examples shown in U.S. Pat. No. 4,344,574 (cross-flow) and U.S. Pat. No. 4,575,605 (concentric), which both atomize a liquid with a gas at high velocity.
Concentric nebulizers have evolved into models with adjustable inner capillary tubes (see for example U.S. Pat. No. 5,884,846), tips with varying geometry (see for example U.S. Pat. No. 6,032,876), direct injection high efficiency models (see for example U.S. Pat. No. 6,166,379), a supersonic nozzle nebulization apparatus (see for example U.S. Pat. No. 6,009,869), a concentric nebulizer with electrospray capability (see for example U.S. Pat. Nos. 6,478,238 and 6,126,086), and a model with parallel paths of gas (surrounding the liquid capillary) with different velocities to direct the cloud of liquid droplets in a specific direction. A combined cross-flow ultrasonic nebulizer has also been developed (see for example U.S. Pat. No. 4,961,885.)
Other apparatuses and methods for nebulizing or atomizing a liquid solution with gas have been patented including a method of thermal pressurization (U.S. Pat. No. 6,601,776), ultrasonication (U.S. Pat. Nos. 6,555,011; 5,922,247), centrifugal pressurization (U.S. Pat. No. 5,727,541) and specialty nozzles (U.S. Pat. No. 5,269,461). These prior art references support the claimed method when the atomized liquid is combined with a stream of gas moving at substantial velocity.
Prior art patents also include any process which combines an energy field and an oxidant for the treatment of gases, liquids and solids in bulk (see U.S. Pat. Nos. 6,761,863; 6,761,729; 6,555,835; 6,468,433; 6,264,899; 5,765,403; 5,688,378; 4,816,145; 4,265,747); of particular application are advanced oxidation processes which generate hydroxyl radicals (OH.) for oxidative treatment of media (see U.S. Pat. Nos. 6,780,306; 6,630,105; 6,361,697; 6,328,898; 6,264,899; 6,200,466; 6,030,526; 5,512,244; 5,364,537; 5,213,759; 4,849,114).
Liquid treatment systems include compounded reactors geometrically shaped to enhance internally applied UV energy (see U.S. Pat. No. 6,555,011); mixing oxygen, ozone and or hydrogen peroxide into the liquid and contacting the mixture with a free radical inducer (see U.S. Pat. No. 6,361,697); pulse-discharge treatment of oxygen saturated liquid (see U.S. Pat. No. 6,328,898); treatment of water with blackbody radiation (see U.S. Pat. No. 6,200,466); dual annular UV reactor which respectively form ozone from dissolved oxygen and then initiate free radical formation with photolysis of titanium dioxide (see U.S. Pat. No. 6,030,526); dissolution of UV treated humid air, referred to as active air (containing only peroxide and hydroxyl radicals) into a liquid (see U.S. Pat. No. 5,765,403); dissolved oxygen and or photoabsorbers (metals/cations) are irradiated in the liquid being treated; combining ozone and hydrogen peroxide in water to create free radicals (U.S. Pat. No. 5,634,537); dissolved ozone and hydrogen peroxide irradiated with UV light (U.S. Pat. No. 4,849,114); laser disinfection of fluids (U.S. Pat. Nos. 4,816,145; 4,265,747)
Surface decontamination systems include a wand which sprays (using a nozzle) ozone combined with water vapor and hydrogen peroxide onto surfaces which are irradiated by a UV source (either a lamp or a fiber optic cable) on the tip of the wand (see U.S. Pat. No. 6,630,105); a reaction chamber in which the object being treated is heated on a sample stage while being irradiated from above with a UV lamp in an ozone atmosphere; sterilization of an object by exposure to an activated gas medium, composed of irradiated SF6, H2O, O2, H2S, CO, C2H2, Hg, NO, Cl2, N2O, C2H6 or mixtures thereof. (U.S. Pat. No. 5,512,244); ultrasonic nebulization of antiseptic solution (U.S. Pat. No. 5,449,502); and wound treatment with ultrasonic atomization of liquid and laser light (U.S. Pat. No. 6,761,729). A spray device which is based on ICP-MS nebulizer technology also exists for the misting of surfaces with various liquids and gases (U.S. Pat. No. 6,848,633).
Gas purification systems include a method of removing pollutants from flue gas by ozonation of the gas, followed by wet scrubbing, followed by ultra-violet radiation (see U.S. Pat. No. 6,761,863); in this invention, NOx, SOx, and Hg are oxidized by ozone and UV radiation to water soluble species which are removed from the gas phase into the liquid phase. The concentric nebulization of ozone with water is also patent pending for the disinfection of surfaces and treatment of gaseous odors (2004/0096354 A1). Pressurization systems in prior art allow for greater mass transfer of gas into liquids (see U.S. Pat. No. 5,971,368).
Prior art also involves catalysts which can be employed for photolytic production of hydroxyl radicals (see U.S. Pat. No. 6,866,755) include titanium dioxide (TiO2), tungsten oxide (WO3), zinc oxide (ZnO) and other semiconductor catalysts which produce electron hole pairs when irradiated with ultraviolet or ionizing energy; catalysts which generally speed up reaction rates are also applicable.
The method of treatment of media with nebulized oxidant combined with a radiation or energy field and catalyst is unique to the present invention. This new method is designed for superior treatment efficiency due to increased surface area for reaction between oxidants, radiation and constituent requiring oxidation leading to overall more rapid treatment time; it is also a convenient method of generating reactive oxidants for immediate application to a surface without damaging or weakening the surface with direct application of radiation or energy.
The following above-discussed US patents are listed in the following table, each patent hereby incorporated herein by reference:
The method of the present invention involves combining an oxidant into a liquid solution or gas through nebulization or atomization. This dispersion process also promotes interaction of the gaseous and liquid molecules which promotes oxidation reactions. The oxidant may itself be a liquid or a gas. When the oxidant is a liquid, it can be delivered undiluted or combined with a solvent or combined with the liquid to be treated. When the oxidant is a gas, it is used by itself or can be combined with the gas to be treated as the carrier gas for nebulization or atomization. As used herein, nebulizing and atomizing are interchangeable, each being defined as a process that includes the mechanical, electrical (e.g. electrospray, see http://www.newobjective.com/electrospray/index.html) or ultrasonic subdivision of a liquid to produce drops or droplets. The oxidant gas or oxidant/polluted gas mixture may then be nebulized with a liquid into the radiation field.
Ultraviolet or ionizing radiation is used to initiate reactions which form highly reactive oxidant species, such as free radicals (OH.); the radiation itself will also decompose some organic species (dependent on bond dissociation energies) but the combination of radiation and chemical oxidation as an advanced oxidation process will decompose all organics as well as oxidize metals and kill microorganisms. The frequency of energy used must be chosen based on the absorption requirements of the employed oxidant. For example, ozone is effectively decomposed into singlet oxygen by electromagnetic radiation with a wavelength less than approximately 300 nm and water is decomposed into hydroxyl radicals at a wavelength less than approximately 190 nm. Gamma rays (wavelengths less than approximately 0.1 nm) are already present when waste being treated is radioactive so the natural energy source within the waste may be incorporated into the design. All gamma radiation induces hydroxyl radical formation in water and also decomposes organics. Sonic energy induces hydroxyl radical formation through cavitation.
The method of the present invention may also be used to carry out a reduction instead of an oxidation reaction. In such a case, the invention can include a method of treating a fluid stream comprising the steps of: providing a nebulizer having a liquid inlet and a gas inlet that each communicate with an outlet; transmitting an influent fluid stream to the liquid inlet; transmitting an influent carrier gas stream to the gas inlet; using the gas stream to atomize the fluid that is emitted by the outlet, forming small droplets downstream of the outlet; and treating the atomized fluid of step “d” with a radiation field, wherein a constituent is reduced instead of oxidized.
For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements and wherein:
An example of a nebulizer 10 which can be used to combine liquid and gas is shown in
Nebulizer 10 provides a pair of inlets 1, 2. Inlet 1 is a flow inlet that is used to introduce a liquid to be nebulized. The inlet 2 is an inlet for introducing a carrier gas. A liquid discharge orifice 3 and a gas discharge orifice 9 is provided at distal end portion 13 of nebulizer 10 opposite the flow inlets 1, 2 as shown in
A nebulized cloud 4 is discharged as indicated by arrow 8 in
The treatment of EDTA solution by nebulized hydrogen peroxide and or ozone in a 254 nm or combined 185/254 nm UV radiation field is shown in
The oxidation of Cr(III) to Cr(VI) by nebulized ozone in a 254 nm UV radiation field is shown in
The embodiments of the present invention described below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather the embodiments are chosen and described so that others skilled in the art may appreciate and understand the principles and practices of the present invention.
This example illustrates the mechanism by which a liquid is treated. The liquid requiring treatment may be blended with another liquid (a solvent or oxidant chosen based on the application of the method) and is pumped through the inner capillary tube through the liquid inlet 1 of the nebulizer. A carrier gas, which may also be an oxidant, is routed through the gas inlet 2 of the nebulizer. The liquid requiring treatment is atomized into small droplets by the carrier gas at the tip of the nebulizer 3. The liquid droplets and gas are injected into an energy field 4; the tip of the nebulizer may also be coated with a photocatalyst which, when inserted into a ultraviolet or ionizing radiation field will promote oxidation reactions. The liquid and/or gas oxidant as well as any nanoparticulate photocatalyst added to the liquid or gas will be energized by the field to form excited species, such as free radicals, which are more powerful oxidants than the parent compound. Gas oxidants will oxidize the contaminants in the liquid at the surface of the droplets and liquid oxidants will oxidize the contaminants inside the droplets. Dose of the oxidants must be designed based on the concentration of contaminant.
Examples of gaseous oxidants which may be used as parent compounds to form reactive gas or dissolved species include but are not limited to:
Examples of liquid oxidants which may be used as parent compounds to form reactive dissolved species include but are not limited to:
Examples of catalysts which may be used to promote oxidation reactions include but are not limited to:
1. Titanium dioxide (TiO2)
2. Tungsten oxide (WO3)
3. Zinc Oxide (ZnO)
4. Tantalum and Nickel Oxides Cocatalyst
Examples of the energy field which may be used to promote reactive species formation include but are not limited to:
1. Ultraviolet radiation (UV)
2. Sonication
3. X-Rays
4. Gamma Rays
5. Microwaves
This example illustrates the mechanism by which a contaminated gas is treated. The gas requiring treatment may be blended with another gas before being routed through the gas inlet 2 of the nebulizer. A liquid solvent and/or oxidant, chosen based on the application of the method, is pumped through the inner capillary tube through the liquid inlet 1 of the nebulizer. Liquid droplets are formed from the velocity of the gas at the tip of the nebulizer 3 and both are injected into the energy field 4. Particulates and volatile organic or inorganic species in the gas requiring treatment may be scrubbed in the nebulized liquid droplets before or after oxidation to soluble species. Oxidation may occur in the gas phase by the direct action of the energy field, or by excited species formed in the gas, or may occur in the liquid phase. Gaseous organic species may also be mineralized to carbon dioxide (CO2) by oxidants at the surface of the liquid. Dose of the oxidants can be designed based on the concentration of contaminant.
The examples of gas and liquid oxidants as well as energy fields and catalysts described in Example 1 are also applicable in this example.
This embodiment can be specifically employed in devices for the purification and decontamination of air in rooms or within ventilation systems.
A gas and liquid are simultaneously treated. The combined methods described in examples 1 and 2 are simultaneously employed to treat a contaminated gas and a contaminated liquid.
This embodiment can be specifically employed in a compact device for the simultaneous treatment of drinking water and indoor air.
A surface 12 is treated by the nebulized excited mist/cloud 11. A liquid oxidant and/or solvent is pumped through the inner capillary tube or conduit 5 via liquid inlet 1 of the nebulizer 10 (see arrow 14). A carrier gas, which may also be an oxidant, is routed through the gas inlet 2 of the nebulizer 10 (see arrow 15). The liquid is atomized into small droplets 7 by the carrier gas at the distal tip 13 of the nebulizer 10 and are injected with the gas into an energy field 11. The energy field 11 can be produced from a collimating source 16 so that the energy field 11 is parallel to but not touching the surface 8.
The following is a list of parts and materials suitable for use in the present invention.
All measurements disclosed herein are at standard temperature and pressure, at sea level on Earth, unless indicated otherwise. All materials used or intended to be used in a human being are biocompatible, unless indicated otherwise.
The foregoing embodiments are presented by way of example only; the scope of the present invention is to be limited only by the following claims.
Priority of U.S. Provisional Patent Application Ser. No. 60/631,781, filed 30 Nov. 2004, incorporated herein by reference, is hereby claimed.
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