METHOD OF REGENERATING CHROMATE ZINC PASSIVATION SOLUTION Russian patent published in 2019 - IPC C25D21/16 C01G37/00 

FIELD: chemistry.

SUBSTANCE: invention relates to methods of electrochemical recovery of chromate solutions used for passivation of zinc coatings, and can be used in electroplating shops and sections to prevent formation of liquid and solid wastes containing compounds of zinc, hexa- and trivalent chromium. Regeneration is carried out in anode chamber of two-chamber electrolytic cell with anode made of platinized titanium or niobium. Cathode chamber is separated from the anode chamber by a cation-exchange membrane, and electrolysis is carried out in two stages. At first step, cathode chamber comprises sulphuric acid solution 50–100 g/l and through electrolytic cell passes through 40–80 A⋅h/l of electricity at cathode and anode current density of 3–5 A/dm², then catholyte pH is increased to 3–4 and 10–20 A⋅h/l of electricity is passed at cathode and anode current density of 0.5–2 A/dm².

EFFECT: method enables to remove zinc ions from catholyte with simultaneous elimination of growth of zinc dendrites.

1 cl, 3 ex