Process for desalination with chlor-alkali production in a mercury diaphragm cell

Claim 1

A novel process for the production of deionized water, alkali metal hydroxide, halogen, and hydrogen from an anolyte comprising an aqueous saline solution the solutes of which comprise alkali metal halides, said halides being selected from the group consisting of chloride and bromide, said anolyte being continuously influent to the anodic compartment of an electrolytic cell, said process being characterized by two alternating phases, a first of said phases comprising the electrosorption of anions in said anolyte on the surface of a porous anode immersed in said anolyte, said anode being impressed with a voltage lower than the discharge D.C. voltage for said anions, said voltage activating transmission of cations in said anolyte from said anodic compartment thru a cation-permeable diaphragm structure separating said anodic compartment from a cathodic compartment of said cell, said cations being then transmitted by said impressed voltage thru a catholyte comprised of an aqueous alkali metal hydroxide solution continuously circulated thru said cathodic compartment, said anolyte and said catholyte being separately maintained, said cations being then electrosorbed on the surface of a porous cathode immersed in said catholyte, said cathode being impressed by a lower than discharge D.C. voltage for said cations, the so formed at least partly deionized water being effluent from said anodic compartment during said first phase of said process, and a second of said alternating phases comprising the raising of the D.C. voltage of both said anode and said cathode to or above the voltage necessary for electrical discharge of the said electrosorbed anions and cations respectively, the so formed halogen being effluent with said anolyte and the so formed alkali metal hydroxide and hydrogen being effluent with said catholyte during said second phase, and finally the voltage of both said anode and said cathode being lowered as specified above for said first phase as part of an alternation to said first phase of said novel process.