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EVALUATION OF AN ELECTRODIALYTIC PROCESS FOR PURIFICATION OF HEXAVALENT CHROMIUM SOLUTIONS
Citation:
Folsom, D. W., J. A. Jones, AND R. F. Olfenbuttel. EVALUATION OF AN ELECTRODIALYTIC PROCESS FOR PURIFICATION OF HEXAVALENT CHROMIUM SOLUTIONS. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-94/071 (NTIS 94-165214), 1994.
Description:
This evaluation addresses the waste reduction and economics of an electrodialytic process that can be used to selectively remove impurities that build up in chromic acid solutions with use. The removal of impurities extends the useful life of the chromic acid solution and avoids periodic replacement of the solution. The electrodialytic units tested in this evaluation were manufactured by lonsep. The units were tested at SL Modern Hard Chrome in Camden, New Jersey, for a hard chromium plating solution and at Paramax in St. Paul, Minnesota, for a chromic acid solution etching copper from printed wire boards. The electrodialytic process was found to effectively remove the impurities that build up in chromic acid solutions. The rate of return on investment varied from being not cost effective to a payback of less than 5 years. The payback is a function of the rate of contaminant buildup in the solution – the more frequently a solution must be replaced when contaminants are not removed, the shorter the payback after an electrolytic process is installed. There was a waste reduction of 68.4 kg (151 Ib) annually in chromium reaching the environment from the chromium plating operation and a projected reduction of 4,410 kg (9,700 Ib) in chromium reaching the environment from the copper etching operation. This report was submitted in partial fulfillment of Contract Number 68-CO-0003, Work Assignment 3-36, under the sponsorship of the U.S. Environmental Protection Agency. The report covers the period from May 1991 through January 1994 and work was completed as of January 24, 1994.