In Process Contaminant Removal from Chromium Electroplating Baths Using a Fuel Cell Electrode Ion Exchange Membrane ProcessEPA Grant Number: R827125
Title: In Process Contaminant Removal from Chromium Electroplating Baths Using a Fuel Cell Electrode Ion Exchange Membrane Process
Investigators: Chang, H. Ted , Holsen, Thomas M. , Selman, J. Robert , Smotkin, Eugene S.
Current Investigators: Khalili, N. R. , Ahmed, M. I. , Donepudi, V. S. , Holsen, Thomas M. , Huang, Kuo-Lin , Kizilel, Riza , Kwiecien, Malgorzata , Schrodt, Ariel G. , Selman, J. Robert
Institution: Illinois Institute of Technology , Clarkson University
EPA Project Officer: Shapiro, Paul
Project Period: October 1, 1998 through September 30, 2001
Project Amount: $331,389
RFA: Exploratory Research - Environmental Engineering (1998) RFA Text | Recipients Lists
Research Category: Engineering and Environmental Chemistry , Sustainability , Land and Waste Management
There are three objectives for this study. (1) To design, construct and test a bench scale fuel cell electrode-ion exchange membrane process (FCMP) to remove contaminants from chromium plating solution. (2) To repeat the laboratory experiments in an actual operating plating shop to determine if the FCMP removes contaminants and extends plating batch lives under actual plating conditions. (3) To develop a detailed mathematical model of the FCMP to optimize the design and operation of the process.
Spent plating solutions are generated when the chromic acid baths become contaminated by the buildup of trivalent chromium and an increase in the concentration of heavy metals. A portion of the bath must then be discarded even though it contains large amounts of chromic acid. Our previous work using a laboratory-scale porous ceramic membrane cell has shown that metal impurities present in hard-chromium plating solutions can be removed and concentrated as a metal hydroxide sludge by operating a parallel, "in-tank", small-scale electrolysis process. However, this process is difficult to operate and energy intensive. To overcome these difficulties a FCMP will be fabricated, which will have a fuel cell electrode as cathode and a Nafion membrane separating the plating bath from the catholyte where the impurity metals are concentrated. This FCMP will be suspended in a tank containing simulated plating solution and surrounded by a perforated oxide-coated lead anode. When a power supply is connected, and air is supplied to the fuel cell electrode, metal contaminants will be drawn through the membrane into the catholyte and trivalent chromium in the bath is oxidized to hexavalent chromium at the outer lead anode. This process will be tested at both bench and field scale. A detailed electrochemical model will also be developed to optimize the process performance.
The successful completion of this project will result in techniques to extend the life of chromium plating baths, perhaps indefinitely. This will significantly decrease the amount of chromium-containing sludge that is generated and disposed of. The proposed method treats the entrained metal at its source without modification of the production scheme, thereby maximizing the impact of the technology.