Process for regenerating spent chromic acid solutions

摘要

The present invention relates to a process for regenerating chromic acid solutions which have been used in etching, anodising, chromating, roughening of plastic surfaces, oxidising organic chemicals and the like, but particularly for chromium plating. According to the invention, an electrolysis cell having a chromic acid-resistant cation-exchange membrane and an acid catholyte is connected in parallel with a cation exchanger, the catholyte circulates pseudo-continually from the cathode space of the electrolysis cell to the cation exchanger and back. The exchange resin removes all metal ions so effectively that their activity is no longer sufficient for any appreciable deposition on the cathodes. The cathodes remain clean and do not have to be lifted out of the electrolysis bath and have the deposits chipped off. The worked up electrolyte is reusable for a long time. The increase in the operating life enables materials to be used which have hitherto been excluded for cost reasons. <IMAGE>