Patent ID: 7824538

Claim:
A process for purifying a recycle base solution waste stream of a composition comprising a quaternary ammonium hydroxide comprising the steps of (a) providing an electrolysis cell which consisting of an anolyte compartment containing an anode, a catholyte compartment containing a cathode, and a cation-selective membrane separating the anolyte and catholyte compartments, (b) charging the recycle base solution waste stream comprising an aqueous solution of the quaternary ammonium hydroxide that was used in the production of 4-aminodiphenylamine, to be purified to the anolyte compartment and charging water, optionally containing a quaternary ammonium hydroxide, to the catholyte compartment, (c) passing a current through the electrolysis cell to produce a purified aqueous quaternary ammonium hydroxide solution in the catholyte compartment, (d) recovering the purified aqueous quaternary ammonium hydroxide solution from the catholyte compartment, (e) washing the anolyte compartment with a suitable solvent to dissolve solid materials fouling the anode and the anolyte compartment, the suitable solvent being one selected from the group of aniline, N,N-dimethylformamide, N-methyl-2-pyrrolidone, and dimethyl sulfoxide, and (f) repeating steps (b)-(e).