Investigation Into Rejuvenation of Spent Chromium Plating Solutions by Bipolar Membrane Electrodialysis

Hexavalent chromium electroplating can form decorative or engineered chrome coatings, however it generates serious Cr(VI) con-tamination. Rejuvenation and reusage of spent chromium plating solutions can powerfully avoid emission of pollutant. Electrodialysis is an effective method to separate impurity cations mixed in spent chrome solutions. In conventional electrodialysis stacks, cations can be deposited on cathodes and current efficiency is decreased. Thus, the bipolar membrane electrodialysis is applied to dispose the cupric (Cu(II)) and ferric (Fe(III)) ions as impurity cations mixed in chrome solutions. Influencing factors on impurity cations removal efficiency were explored including operation conditions, membrane material, and chromium ion concentration in the bipolar mem-brane electrodialysis system. The results reveal that Cr(VI) concentration is a critical factor on the efficiency of rejuvenation