Mediated electrochemical oxidation of inorganic materials

• US 7,531,710 B2
• Filed: 09/10/2003
• Issued: 05/12/2009
• Est. Priority Date: 09/10/2002
• Status: Expired due to Fees

• Current Assignee: Lnc Scimist
• Original Assignee: Scimist Corporation
• Inventors: Carson, Roger W., Bremer, Bruce W.
• Primary Examiner(s): Johnson; Edward M
• Application Number:
  US10/527,103
• Publication Number:
  US 20050245784A1
• Time in Patent Office: 2,071 Days
• Field of Search: 588/303, 588/320, 588/405, 588/410, 588/900
• US Class Current: 588/410
• CPC Class Codes: A61L 11/00 Methods specially adapted for refuse disintegrating medical waste B02C19/0075; disposal of medical waste B09B3/00
• CPC Class Codes: A61L 2/025 Ultrasonics
• CPC Class Codes: A61L 2/035 Electrolysis
• CPC Class Codes: A61L 2/10 Ultraviolet radiation
• CPC Class Codes: A61L 2/24 Apparatus using programmed or automatic operation
• CPC Class Codes: C02F 1/4672 by electrooxydation
• CPC Class Codes: C22B 3/045 Leaching using electrochemical processes
• CPC Class Codes: C22B 7/00 Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals briquetting of scrap C22B1/248; preliminary treatment of scrap C22B1/005
• CPC Class Codes: C25D 11/005 Apparatus specially adapted for electrolytic conversion coating apparatus in general for electrolytic coating C25D17/00
• CPC Class Codes: C25D 17/002 Cell separation, e.g. membranes, diaphragms
• CPC Class Codes: Y02P 10/20 Recycling
• CPC Class Codes: Y10S 588/90 Apparatus

Abstract

A mediated electrochemical oxidation process and apparatus for the use of mediated electrochemical oxidation for the oxidation, conversion/recovery, and decontamination of inorganic solids, liquids, and gases where higher oxidation states exist. Inorganic materials are introduced into an apparatus for contacting the inorganic materials with an electrolyte containing the oxidized form of one or more reversible redox couples, at least one of which is produced electrochemically by anodic oxidation at the anode of an electrochemical cell. The oxidized forms of any other redox couples present are produced either by similar anodic oxidation or reaction with the oxidized form of other redox couples present and capable of affecting the required redox reaction. The oxidized species of the redox couples oxidize the inorganic waste molecules and are converted to their reduced form, whereupon they are reoxidized by either of the aforementioned mechanisms and the redox cycle continues.

Claims

1. A treatment of waste process for the use of mediated electrochemical oxidation (MEO) for the oxidation, conversion/recovery, and decontamination of all previously defined inorganic solid, liquid, or gas where higher oxidation states exist selected from a group consisting of halogenated inorganic compounds (except fluorinated), inorganic pesticides and herbicides, inorganic fertilizers, carbon residues, incinerator residue, inorganic carbon compounds, mineral formations, mining tailings, inorganic salts, metals and metal compounds, and combinations thereof;

and combined waste (a mixture of any of the foregoing with each other or other non-inorganic materials) further comprising disposing an electrolyte in an electrochemical cell, separating the electrolyte into an anolyte portion and a catholyte portion with an ion-selective membrane, semi permeable, microporous polymer, ceramic or glass frit membrane;

applying a direct current voltage between the anolyte portion and the catholyte portion, placing the waste and/or inorganic materials in the anolyte portion, and oxidizing the waste and/or inorganic materials in the anolyte portion with a mediated electrochemical oxidation (MEO) process, wherein the anolyte portion further comprises a mediator or mediators (oxidizing species) in aqueous solution and containing an acid, neutral or alkaline electrolytes, and wherein the mediator oxidizing species are simple anion redox couples described in Table I as below;

Type I isopolyanions complex anion redox couples formed by incorporation of Mo, W, V, Nb, Ta, or mixtures thereof as addenda atoms;

Type I heteropolyanions complex anion redox couples formed by incorporation in to Type I isopolyanions as heteroatoms any of the elements listed in Table II either singly or in combination thereof, or heteropolyanions complex anion redox couples containing at least one heteroatom type element contained in both Table I and Table II below or combinations of the mediator oxidizing species from any or all of these generic groups;

2. The process of claim 1, further comprising adding stabilizing compounds to the electrolyte for overcoming and stabilizing the short lifetime of oxidized forms of higher oxidation state species of the mediator oxidizing species, and further comprising additives disposed in the electrolyte thereby increasing the kinetics of the mediated electrochemical processes of the mediated electrochemical processes while keeping it from becoming directly involved in the oxidizing of the waste and/or inorganic materials, and stabilizer compounds disposed in the electrolyte for stabilizing higher oxidation state species of oxidized forms of the reversible redox couples used as the mediator oxidizing species in the electrolyte.

3. The process of claim 1, wherein the mediator oxidizing species are super oxidizers which exhibit oxidation potentials of at least 1.7 volts at 1 molar, 25°

C. and pH 1 and which are redox couple species that have the capability of producing free radicals of hydroxyl or perhydroxyl, and further comprising creating free radical secondary oxidizers by reacting the super oxidizers with water, adding energy from an energy source, ultra sonic and/or ultraviolet, to the anolyte portion and augmenting the secondary oxidation processes, breaking down hydrogen peroxide in the anolyte portion into hydroxyl free radicals, and increasing an oxidizing effect of the secondary oxidation processes, and further comprising generating inorganic free radicals in acqueous solutions from a group consisting of carbonate, azide, nitrite, nitrate, phosphite, phosphate, sulfite, sulfate, selenite, thiocyanate, chloride, bromide, iodide, and formate oxidizing species and combinations thereof.

4. The process of claim 1, further comprising using an alkaline solution, aiding decomposing of the biological materials in waste and/or inorganic materials derived from base promoted ester hydrolysis, saponification, of fatty acids, and forming water soluble alkali metal salts of the fatty acids and glycerin in a process similar to the production of soap from animal fat by introducing it into a hot aqueous lye solution.

5. The process of claim 1, further comprising using an alkaline anolyte solution for aiding decomposing the materials, for absorbing CO₂ from the oxidizing of waste and/or inorganic materials and forming alkali metal bicarbonate/carbonate solutions, which subsequently circulate through the electrochemical cell, producing percarbonate oxidizers.

6. The process of claim 1, further comprising impressing an AC voltage upon the direct current voltage for retarding formation of cell performance limiting surface films on the electrodes or the membrane.

7. The process of claim 1, further comprising adjusting temperature between 0°

C. and slightly below the boiling point of the anolyte portion before it enters the electrochemical cell for enhancing generation of oxidized forms of the mediator oxidizing species, and adjusting the temperature between 0°

C. and below the boiling temperature of the anolyte portion entering the anolyte reaction chamber affecting desired chemical reactions at desired rates.

8. The process of claim 1, further comprising introducing an ultrasonic energy into the anolyte portion, rupturing cell membranes in the biological materials in waste and/or inorganic materials by momentarily raising local temperature and pressure within the cell membranes with the ultrasonic energy to above several thousand degrees and thousand atmospheres, and causing cell membrane failure, and wherein the added energy comprises using ultrasonic energy and inducing microscopic bubble expansion and implosion for reducing in size individual second phase mixed waste volumes dispersed in the anolyte.

9. The process of claim 1, further comprising inorganic waste containing elements that are identified in Table I as anion redox couples, they become possible mediated redox couples when the oxidation of the inorganic waste releases them into solution as the reduced form of the redox couple and are raised to the oxidized form when they pass through the electrochemical cell.

10. The process of claim 1, further comprising introducing ultraviolet energy into the anolyte portion and decomposing hydrogen peroxide into hydroxyl free radicals therein, thereby increasing efficiency of the process by converting products of electron consuming parasitic reactions, hydrogen peroxide, into viable free radical secondary oxidizers without consumption of additional electrons.

11. The process of claim 1, further comprising adding a surfactant to the anolyte portion for promoting dispersion of the waste and/or inorganic materials or intermediate stage reaction products within the aqueous solution when the waste and/or inorganic materials or reaction products are not water-soluble and tend to form immiscible layers.

12. The process of claim 1, further comprising attacking specific organic molecules in the waste and/or inorganic materials with the mediator oxidizing species while operating at a sufficiently low temperatures and preventing formation of dioxins and furans.

13. The process of claim 1, further comprising breaking down the waste and/or inorganic materials into biological and organic compounds and attacking these compounds using as the mediator simple and/or complex anion redox couple mediators or inorganic free radicals and generating organic free radicals.

14. The process of claim 1, further comprising raising normal valence state mediator anions to a higher valence state by stripping the mediator anions of electrons in the electrochemical cell, wherein oxidized forms of weaker redox couples present in the mediator oxidizing species are produced by similar anodic oxidation or reaction with oxidized forms of stronger redox couples present and the oxidized species of the redox couples oxidize molecules of the waste and/or inorganic materials and are themselves converted to their reduced form, whereupon they are oxidized by the aforementioned mechanisms and the redox cycle continues.

17. The process of claim 1, further comprising using the mediator oxidizing species that are found in situ in the waste and/or inorganic materials to be decomposed, by circulating the waste and/or inorganic materials-anolyte mixture through the electrochemical cell where in an oxidized form of an in situ reversible redox couple is formed by anodic oxidizing or reacting with an oxidized form of a more powerful redox couple added to or already present in the anolyte portion and anodically oxidized in the electrochemical cell, thereby destroying the biological and organic materials in the waste and/or inorganic materials.

19. The process of claim 1, wherein the oxidation potential of redox reactions of the mediator oxidizing species and the biological and organic molecules in the waste and/or inorganic materials producing hydrogen ions are inversely proportional to electrolyte pH, and thus with a selection of a mediator redox couple increasing the electrolyte pH reduces the electric potential required, thereby reducing electric power consumed per unit mass of the waste and/or inorganic materials destroyed.

15. A process for treating and waste comprising oxidizing waste and/or inorganic materials, comprising circulating anions of mediator oxidizing species in an electrolyte through an electrochemical cell with an ion-selective membrane, semi permeable, microporous polymer, ceramic or glass frit membrane, and affecting anodic oxidation of reduced forms of reversible redox couples into oxidized forms, contacting the anions with the waste and/or inorganic materials in an anolyte portion of the electrolyte in a primary oxidation process, involving super oxidizer anions, having an oxidation potential above a threshold value of 1.7 volts at 1 molar, 25°

C. and pH1 are present there is creating a free radical oxidizer driven secondary oxidation process, adding energy from an energy source to the anolyte portion and augmenting the secondary oxidation processes, breaking down hydrogen peroxide in the anolyte portion into hydroxyl free radicals, and increasing an oxidizing effect of the secondary oxidation processes, wherein the mediator oxidizing species are simple anion redox couples described in Table I as below;

Type I isopolyanions complex anion redox couples formed by incorporation of Mo, W, V, Nb, Ta, or mixtures thereof as addenda atoms;

Type I heteropolyanions complex anion redox couples formed by incorporation in to Type I isopolyanions as heteroatoms any of the elements listed in Table II either singly or in combination thereof, or heteropolyanions complex anion redox couples containing at least one heteroatom type element contained in both Table I and Table II below or combinations of the mediator oxidizing species from any or all of these generic groups;

16. The process of claim 15, wherein the adding energy comprises introducing an ultrasonic energy source and/or an ultraviolet energy source into the anolyte portion, promoting the formation of the hydroxyl free radicals, wherein the added energy comprises using ultrasonic energy and inducing microscopic bubble expansion and implosion for reducing in size individual second phase waste and/or inorganic materials volumes dispersed in the anolyte.

18. The process of claim 15, further comprising using an alkaline electrolyte selected from a group consisting of NaOH or KOH and combinations thereof, with the mediator oxidizing species, wherein a reduced form of a mediator redox couple has sufficient solubility in said electrolyte for allowing desired oxidation of the biological and organic materials in the waste and/or inorganic materials.

20. The process of claim 15, wherein the electrolyte is an aqueous solution chosen from the group consisting of acids, alkalines and salt electrolytes and mixtures of salt and either acids or alkalines and combinations thereof.

21. The process of claim 15, further comprising interchanging the mediator oxidizing species without changing equipment, and wherein the anolyte and catholyte portions of electrolyte are independent of one another and comprise aqueous solutions selected from the group consisting of acids, alkali or salts or mixtures of salt and either acids or alkalines and combinations thereof.

22. The process of claim 15, wherein the oxidizing and destroying waste and/or inorganic materials comprises destroying and oxidizing solid waste and/or inorganic materials, comprises oxidizing and destroying liquid waste and/or inorganic materials, comprises treating and oxidizing gas waste and/or inorganic materials, comprises oxidizing and destroying a combination of liquids, solids, and gases in waste and/or inorganic materials.

23. The process of claim 15, further comprising requiring removing and treating precipitates resulting from combinations of the oxidizing species and other species released from the waste and/or inorganic materials during destruction and sterilization.

24. The process of claim 15, further comprising a catholyte portion of the electrolyte, and wherein the anolyte and catholyte portions of electrolyte are independent of one another, and comprise aqueous solutions selected from a group consisting of acids, alkali or salt or a mixture of salt and either acids or alkali and combinations thereof.

25. The process of claim 15, further comprising separating a catholyte portion of the electrolyte from the anolyte portion with a membrane, operating the electrochemical cell at a current density such that there is the possibility that metallic anions may leak through the membrane in small quantities, typically 0.5 amps per square centimeter of membrane or less, and recovering the metallic anions from the catholyte through a device such as a resin column, thus allowing a greater rate of destruction of waste and/or inorganic materials in the anolyte portion.

26. The process of claim 15, wherein the catholyte solution portion further comprises an aqueous solution and the electrolyte in the solution is composed of acids, alkali or salts, and further comprising adding oxygen to this the solution when HNO₃ or NO₃ can occur in the catholyte portion, controlling concentration of electrolyte in the catholyte to maintain conductivity of the catholyte portion desired in the electrochemical cell, providing mechanical mixing and/or ultrasonic energy induced microscopic bubble formation, and implosion for vigorous mixing in the catholyte solution for oxidizing the nitrous acid and small amounts of nitrogen oxides NO_X,introducing air into the catholyte portion for promoting the oxidizing of the nitrous acid and the small amounts of NOR, and diluting any hydrogen produced in the catholyte portion before releasing the air and hydrogen.