Purifying Air Force Plating Baths by Chelate Ion Exchange

摘要

During plating operations at various Air Force Air Logistics Centers, the plating baths become contaminated with heavy metals. The present Air Force practice is to replace the baths and dispose of the contaminated baths. The objective of this study is to determine the feasibility of using chelate ion exchange for the purification and reuse of the plating baths. Removal of the contaminant metals without removing the plating metals will extend the operating life of the baths. The test program was carried out in pilot scale ion exchange columns and showed that electroless nickel, electrolytic nickel, nickel strike, and hydrochloric acid etch bath could be treated successfully with three chelate resins: Amberlite IRC-718, Cuolite ES-467, and Dowex XFS-4195. The pilot-scale test results were used in the design of a scaled-up chelate ion exchange system capable of treating all four plating baths. The annual costs of operation were about one-third of the present operating cost of replacement and disposal. The paycheck period for the ion exchange system was about 5 months, an exceptionally short time to recover the capital costs of the system. The results of the study show that chelate ion exchange is an economically viable process for the purification and reuse of contaminated plating baths.