Abstract: A process for the electrolytic production of a chloride-free mixture consisting essentially of sodium and potassium nitrates is disclosed. In this process, an anolyte brine comprised of a mixture of sodium and potassium chlorides dissolved therein is electrolyzed in a membrane type electrolysis type cell to produce a mixed alkali metal hydroxide catholyte solution. The catholyte is reacted with nitric acid to form a mixed potassium-sodium nitrate solution. By properly adjusting the ratio of potassium chloride to sodium chloride concentration in the anolyte brine, a final nitrate product containing about from about 40% to about 80% NaNO.sub.3 and from about 60% to about 20% KNO.sub.3 by weight can be produced. The resulting product, after drying is suitable for use in many solar panel heat transfer applications.

Abstract: An electrode for use in an electrolytic cell, and a method for producing same, wherein said electrode comprises an internal copper conductor and an external element of a second metal, at least a portion of each having contact surfaces being held in intimate contact with the other, said conductor and said element each having a conductive coating applied to the contact surface, said conductive coating comprising between about 20 and about 30 percent indium and between about 80 and about 70 percent gallium, whereby the contact resistance between said conductor and said element is reduced.

Abstract: Described is a process for making a calcium/sodium ferrate adduct with sodium ferrate in a divided-type electrolysis cell. The anolyte chamber of the cell is charged with an aqueous solution of sodium hydroxide and a sodium ferrate-stabilizing proportion of at least one sodium halide salt. The anolyte chamber additionally contains ferric ions [Fe(III)]. The catholyte chamber contains an aqueous sodium hydroxide solution during operation. The source of ferric ion in the anolyte may be either an iron-containing anode or at least one iron-containing compound present in the anolyte solution or both. The preferred material separating the anolyte chamber from the catholyte chamber is comprised of a gas- and hydraulic-impermeable, ionically-conductive, chemically-stable ionomeric film (e.g., a cation-exchange membrane with carboxylic, sulfonic or other inorganic exchange sites).

Abstract: Described is an electrolytic process for producing sodium ferrate [Fe(VI)] in a membrane-type electrolysis cell. The anolyte chamber of the cell is charged with an aqueous solution of sodium hydroxide and a sodium ferrate-stabilizing proportion of at least one sodium halide salt. The anolyte chamber additionally contains ferric ions [Fe(III)]. The catholyte chamber contains an aqueous sodium hydroxide solution during operation. The source of ferric ion in the anolyte may be either an iron-containing anode or at least one iron-containing compound present in the anolyte solution or both. The preferred membrane material for separating the anolyte chamber from the catholyte chamber is comprised of a gas- and hydraulic-impermeable, ionically-conductive, chemically-stable ionomeric film (e.g., a cation-exchange membrane) with carboxylic, sulfunic or other inorganic exchange sites.

Abstract: A process is described for reducing the concentration of oxyhalogen impurities in an alkali metal halide brine recovered from an electrolytic cell which comprises circulating the alkali metal halide brine to a treatment zone outside of the electrolytic cell. Within the treatment zone, the alkali metal halide brine is reacted with oxalic acid while maintaining the alkali metal halide brine at a pH of less than about 4.5. A purified brine having a substantially reduced concentration of oxyhalogen impurities is recovered from the treatment zone. The process may be employed in treating brines recovered from mercury cells and membrane cells for the production of chlorine and alkali metal hydroxides and its employment results in a substantial reduction in the amount of concentrated acid required in brine treatment and a reduction in energy costs for brine purification.

Abstract: Disclosed is a process for making potassium ferrate (K.sub.2 FeO.sub.4) by reacting substantially pure KOH, C1.sub.2, and a ferric salt in the presence of a stabilizing proportion of at least one ferrate-stabilizing compound (e.g., a combination of an alkali metal silicate and an alkali metal iodine-containing salt). The formed K.sub.2 FeO.sub.4 is separated and recovered from other reaction co-products [KCl, H.sub.2 O, KOCl, and Fe(OH).sub.3 ] and excess KOH. Other specific improvements include the following:(i) returning KCl co-product back to a chlor/alkali membrane-type electrolytic cell and then making very pure KOH and Cl.sub.2 ;(ii) recylcing excess KOH back to the ferrate-forming reaction; and(iii) recovering a substantially pure dry solid K.sub.2 FeO.sub.4 product by washing the above-noted K.sub.2 FeO.sub.4 product in DMSO or its equivalent; and then washing with methanol or its equivalent, before drying.

Abstract: A process is disclosed for purifying aqueous solutions of metal hydroxides.An aqueous solution of a metal hydroxide, such as sodium hydroxide, containing a complex of a heavy metal contaminant, such as mercury, is heated.An oxidizing agent, such as hydrogen peroxide, is reacted with the solution to precipitate solid particles of an oxide of the heavy metal, for example, mercuric oxide, in a solution. The solid particles of mercuric oxide are separated from the solution by filtration.The purified solution comprised of water and sodium hydroxide and containing less than about 0.3 part per million mercury by weight is sold commercially. The solid particles of mercuric oxide are landfilled or otherwise utilized.

Abstract: A method of purifying alkali metal chloride brine containing calcium ion impurities which comprises adding to the brine a proportion of an alkali metal carboxylate compound to form an insoluble calcium carboxylate precipitate, separating the insoluble carboxylate precipitate from the brine to purify the brine and recovering the resulting purified brine. The alkali metal carboxylate compound has the formula: ##STR1## wherein Me is an alkali metal and n is an integer from 0 to 6.

Abstract: Concentrated alkali metal hydroxide substantially free of alkali metal halide and other impurities is produced by the electrolysis of an alkali metal halide solution in an electrolytic cell having a dimensionally stable anode and a metal cathode separated by an electrically conductive stable selectively permeable hydrated cation ion-exchange membrane film of a fluorinated copolymer having pendant sulfonic acid groups or derivatives of such groups. The membrane film is capable of use at high temperatures and under severely corrosive chemical conditions for extended periods without degradation.

Abstract: A method and apparatus for in situ reduction of cathode overvoltage in electrolytic cells. The method involves introducing low overvoltage or noble metal ions into the catholyte solution and plating those ions on the cathode in situ. The apparatus includes a low overvoltage or noble metal ion generating device for introducing low overvoltage or noble metal ions into the cathode solution so as to plate them in situ on the cathode during or prior to cell operation.

Abstract: Electrolytic apparatus is described for purifying an aqueous solution of an alkali metal hydroxide containing an impurity of a soluble heavy metal complex comprised of a heavy metal cation and a plurality of anions.For example, an aqueous solution of sodium hydroxide containing a soluble heavy metal complex, such as mercuric polysulfide, [HgS].sup.+ S.sup.-, is charged to the electrolytic chamber of an electrolytic cell. An electric current is employed to reduce heavy metal cations to a separate phase in elemental form, and simultaneously to oxidize anions to a separate phase in elemental form, and to form a slurry of the separate phases in elemental forms in the aqueous solution.The slurry is removed from the electrolytic chamber and the phases of elemental forms are separated from the purified aqueous solution. The purified alkali metal hydroxide solution is sold commercially or otherwise utilized.

Abstract: A process for removing dissolved halogen gas and oxyhalide ions from an aqueous alkali metal halide solution containing them which comprises reacting said aqueous alkali metal halide solution with an inorganic peroxide, and adjusting the pH of said aqueous alkali metal halide solution to a pH within the range from about 6 to about 11 with an inorganic base, whereby a purified alkali metal halide solution of reduced concentration of said dissolved halogen gas and oxyhalide ions is produced.

Abstract: A process is disclosed for purifying aqueous solutions of metal hydroxides.An aqueous solution of a metal hydroxide, such as sodium hydroxide, containing a complex of a heavy metal contaminant, such as mercury, is heated.An oxidizing agent, such as hydrogen peroxide, is reacted with the solution to precipitate solid particles of an oxide of the heavy metal, for example, mercuric oxide, in a solution. The solid particles of mercuric oxide are separated from the solution by filtration.The purified solution comprised of water and sodium hydroxide and containing less than about 0.3 part per million mercury by weight is sold commercially. The solid particles of mercuric oxide are landfilled or otherwise utilized.

Abstract: Current efficiency in an electrolytic membrane cell for the production of concentrated potassium hydroxide is considerably increased by employing in the electrolytic membrane cell a membrane selected from a group consisting of an amine modified perfluorosulfonic acid membrane such as a primary amine, diamine, or polyamine modified perfluorosulfonic acid membrane, and a laminated perfluorosulfonic acid acid membrane, and a laminated perfluorosulfonic acid membrane comprised of at least two unmodified perfluorosulfonic acid membranes of different thickness and different equivalent weight.

Abstract: Improved current efficiency is obtained in an electrolytic membrane cell for the production of potassium hydroxide by employing in combination:(a) a membrane comprised of a carboxylic acid substituted polymer prepared by reacting a fluorinated olefin with a comonomer having a functional group selected from the group consisting of carboxylic acid and a functional group which can be converted to carboxylic acid;(b) a potassium chloride brine feed through the anolyte chamber of the cell having a concentration in the range from about 250 to about 300 grams of potassium chloride per liter;(c) a cell operating temperature in the range from about 90.degree. to about 100.degree. C.

Abstract: Concentrated alkali metal hydroxide substantially free of alkali metal halide and other impurities is produced by the electrolysis of an alkali metal halide solution in an electrolytic cell having a dimensionally stable anode and a metal cathode separated by an electrically conductive stable selectively permeable hydrated cation ion-exchange membrane film of a fluorinated copolymer having pendant sulfonic acid groups or derivatives of such groups. The membrane film is capable of use at high temperatures and under severely corrosive chemical conditions for extended periods without degradation.

Abstract: An electrolytic process is described for purifying an aqueous solution of an alkali metal hydroxide containing an impurity of a soluble heavy metal complex comprised of a heavy metal cation and a plurality of anions.For example, an aqueous solution of sodium hydroxide containing a soluble heavy metal complex, such as mercuric polysulfide, [HgS].sup.+ S.sup.-, is charged to the electrolytic chamber of an electrolytic cell. An electric current is employed to reduce heavy metal cations to a separate phase in elemental form, and simultaneously to oxidize anions to a separate phase in elemental form, and to form a slurry of the separate phases in elemental forms in the aqueous solution.The slurry is removed from the electrolytic chamber and the phases of elemental forms are separated from the purified aqueous solution. The purified alkali metal hydroxide solution is sold commercially or otherwise utilized.

Abstract: Calcium hypochlorite useful as a commercial sanitizing agent and swimming pool disinfectant is produced by a process wherein calcium hydroxide and organic hypochlorite are reacted in a first reaction zone to produce calcium hypochlorite. The portion of the calcium hydroxide remaining unreacted is recovered along with product calcium hypochlorite in a mixture of solids.In a second reaction zone, an aqueous solution of sodium hydroxide is reacted with an organic hypochlorite to form an aqueous phase containing sodium hypochlorite and an organic phase. The aqueous phase is separated from the organic phase.Chlorine is reacted with the mixture of solids of the first reaction zone and the aqueous phase of the second reaction zone in a third reaction zone to produce an aqueous slurry of calcium hypochlorite particles. The calcium hypochlorite particles are thereafter recovered and dried in granular form.

Abstract: An electrolytic process for preparing organic hypohalite compounds from an aqueous brine and organic alcohol solution in a multi-chamber membrane type cell. For example, tertiary butyl hypochlorite is prepared in a membrane cell from tertiary butyl alcohol and a sodium chloride brine. An organic solvent such as carbon tetrachloride can be used to extract the organic hypohalite formed in the aqueous brine phase either during or after electrolysis.

Abstract: An electrolytic cell employing a hydraulically impermeable membrane having a spacing means interposed between the anode and the membrane, is operated by providing a positive pressure differential between the cathode compartment and the anode compartment. The pressure differential is sufficient to maintain contact between the spacer and the membrane to provide uniform spacing between the anode and the membrane. In addition, this process provides sufficient spacing between the membrane and the cathode to provide efficient release of any gas formed and to prevent gas blinding at the cathode. Employing the positive pressure differential enables the cell to be operated at reduced energy costs when producing, for example, concentrated solutions of sodium hydroxide by careful control of the spacing between the membrane and the electrodes.