FIELD: technological processes.
SUBSTANCE: invention relates to a method of regenerating acidic chromate solutions of passivation, clarification-passivation, clarification by reagent-membrane-electrolysis method. Solid sodium or potassium hydroxide or aqueous solutions with concentration of 1–40 wt% are added to the spent solution to achieve solution pH of 4–10 for precipitation of insoluble chromates and/or hydroxides of heavy metals. Precipitation is separated from treated solution by filtration. Obtained filtrate is subjected to membrane electrolysis, for which filtrate is directed into an anode space with an insoluble anode of a two-chamber membrane electrolysis cell with a cation-exchange membrane, where the cathode contains a cathode and a solution of sodium or potassium hydroxide. When the nominal values in the anolyte of concentration of sodium bichromate, sulfuric acid or a mixture of sulfuric and nitric acid corresponding to the fresh solution of passivation, clarification-passivation or clarification are reached, electrolysis is terminated.
EFFECT: technical result consists in improvement of degree of purification and speed of regeneration process, as well as recycling of used chemicals.
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