Selective iron sorption for on-line reclaim of chromate electroplating solution at highly acidic condition

摘要

On-line reclaim process by selective ion sorption for the purification of highly acidic Fe contaminated chromate electroplating bath has been developed. Among many industrial functional resins, Lewatit VPOC1026 implanted with di-(2-ethylhexyl) phosphoric acid (DEHPA) extractant in the polymeric backbone exhibited the highest selectivity of Fe versus Cr but low sorption capacity of Fe. Impregnation of DEHPA on functionalized S957 resin (a sulfonated mono-phosphonic acid resin) exhibited a much enhanced Fe sorption capacity with high Fe selectivity. The enhancement in the adsorption performance of S957 is due to the selective adsorption of DEHPA for Fe(III) complex formation. For the best electroplating performance, the maximum Fe contaminant level in the chromate electroplating bath was determined as 50 mg/L. The developed process could not only maximize electroplating performance but also minimize the usage of original water and the production of waste water. (C) 2015 Elsevier B.V. All rights reserved.