An electrolytic process for separating alkali metal ions from ions of zinc and/or aluminium

摘要

757,928. Separating alkali metal ions from zinc and/or aluminium ions by electrodialysis. ROHM & HAAS CO. Nov. 27, 1953 [Dec. 12, 1952], No. 32978/53. Drawings to Specification. Class 41. Alkali metal ions are separated from an aqueous solution containing them together with zinc and/or aluminium ions by D.C. electrolysis of the solution while placed in an intermediate compartment in an electrolytic cell having an anode compartment which is separated from it by an anionic permselective diaphragm containing an anion exchange resin and which contains an aqueous solution containing hydrogen ions, and a cathode compartment which is separated from the intermediate compartment by a cationic permselective diaphragm containing a cation exchange resin and which contains an aqueous solution containing hydroxyl ions. Typically a mixture of sodium and zinc sulphates is electrolysed in such a cell between platinum electrodes at a current density of 50-150 amps./sq. ft., the anode compartment containing sulphuric acid and the cathode compartment caustic soda. The diaphragms are of polyethylene in which the exchange resins are dispersed as described in Specification 719,315. The anion exchange resin is a strongly basic quaternary ammonium resin made by first chloromethylating and then aminating with a tertiary amine an insoluble cross-linked copolymer of styrene and divinylbenzene as described in Specification 654,706, [Group IV (a)], and the cation exchange resin is a sulphonated copolymer of styrene and divinylbenzene as described in U.S.A. Specification 2,366,007. Each cell compartment has a supply pipe at the top and a drain pipe in the floor. Specifications 450,309, 489,173, 489,437, 498,251, 515,517, 516,609, 521,207, 557,414, [all in Group IV], 566,622, [Group XI],693,166, 720,002, 721,161, [Group IV (a)], and U.S.A. Specification 2,340,111 also are referred to.