Grantee Research Project Results
2000 Progress Report: In Process Contaminant Removal from Chromium Electroplating Baths Using a Fuel Cell Electrode Ion Exchange Membrane Process
EPA Grant Number: R827125Title: In Process Contaminant Removal from Chromium Electroplating Baths Using a Fuel Cell Electrode Ion Exchange Membrane Process
Investigators: Khalili, N. R. , Kwiecien, Malgorzata , Schrodt, Ariel G. , Ahmed, M. I. , Holsen, Thomas M. , Selman, J. Robert , Donepudi, V. S. , Huang, Kuo-Lin , Kizilel, Riza
Institution: Illinois Institute of Technology , Clarkson University
EPA Project Officer: Hahn, Intaek
Project Period: October 1, 1998 through September 30, 2001
Project Period Covered by this Report: October 1, 1999 through September 30, 2000
Project Amount: $331,389
RFA: Exploratory Research - Environmental Engineering (1998) RFA Text | Recipients Lists
Research Category: Safer Chemicals , Sustainable and Healthy Communities , Land and Waste Management
Objective:
The objectives of the research project are to: (1) design, construct and test a bench scale fuel cell electrode ion exchange membrane process (FCMP) to remove contaminants from chromium plating solutions; (2) field test FCMP or its modifications in operating plating shop; and (3) develop a detail working model to optimize the process.
Progress Summary:
The project, corresponding to the three objectives stated above, is divided into three distinct tasks. The progress summary and accomplishments in these tasks during the reporting period are described below:
Task 1a: Design Modification of the Bench Scale Fuel Cell Electrode Ion Exchange Membrane Process (FCMP). During the first year of the project, the experimental cell was designed and tested under simulated plating solution conditions. Although preliminary experiments at IIT confirmed the feasibility of the process as designed, a high amount of platinum (5 mg) was used in configuring the fuel cell electrode. To minimize the cost of the operation and maximize performance efficiency of the fuel cell, during the second year of the project investigation of the process components focused on determination of the transport limitation by Nafion separator and MEA, the effect of platinum (Pt) loading, cation uptake measurements, porosity and water content measurements, and evaluation of the MEA resistance and moisture content relationship. These studies are essential in predicting limiting behavior of Nafion and MEA and the impact of Pt loading.
The new cell design eliminated previously experienced problems of leakage,
helped mixing characteristics of the solution, prevented metal contamination,
and allowed for continuos and leak free measurements throughout the study. In
the new design a graphite block is being sandwiched between two acrylic casts,
and the screws are placed outside of the solutions.
Fuel cell oxygen
electrode performance was studied during the first year of the project. During
this study, monitoring during experiments was performed and as one of the
outputs, polarization curves were obtained. Since the focus of the second year
project was determination of the effect of Pt loading on the cell performance
and ionic flux, four sets of the experiments were carried out to analyze the
process. In each of them overloading (a continuous slow rise in the voltage
necessary to maintain a constant current) appeared to be a major problem.
Previously, the problem was overcome by increasing the amount of platinum on the
MEA. The objective of this year was to investigate the impact of the Pt loading
thus; the attention was focused on how to remove the overloading problem without
increasing the platinum. The following reasons were explored as possible causes
of overloading:
- Continuos increase of contact resistance between MEA and backing plate, due to delamination or corrosion.
- Penetration of the chromic acid electrolyte in the MEA, slowly choking the excess of oxygen to the catalytic reaction sites of the cathode.
- Clogging of the pores in MEA caused by deposition of contaminant metals, with the same effect as (2).
Resistivity of the MEA as a function of moisture content was also investigated to understand the overloading problem. As expected, the resistance of the MEA decreases as the moisture content in the MEA increases. With a very low level of moisture content in the MEA, the value of the resistance reaches to megaohm level. This high level of resistively could significantly contribute to cell overloading.
A modeling approach was launched to understand the behavior of the porous electrode. As a first stage of this process the exchange current density (io) was estimated from the polarization curves obtained in the previous year. This was done with the assumption that we are dealing with planar electrode and that the ohmic and diffusion overpotentials are negligible. The exchange current density (io) was estimated by Tafel kinetic polarization equation. The results of this calculation gave the io of the magnitude 10-3. Similar values ranging form 10-5 to 10-3 were reported in the literature. As a next step the modeling of pores being filled by deposition of metals will be studied.
Task 1b: Determination of the Diffusion Coefficients and Transference Numbers of Species Across Nafion 117 Membrane at Operating Conditions. The cumulative objectives of this project including determination of: (1) diffusion and partition coefficients of metallic impurities (Cu (II), Fe (II), Ni (II), and Cr (III)) found in hard-chrome electroplating bath with Nafion membranes; (2) partition and diffusion coefficients of anions associated with metallic impurities found in hard-chrome electroplating bath with Nafion membranes; and (3) development of a model of cation and anion diffusion through Nafion membrane were carried out during the second year of the project.
The tasks carried out during the second year of the project at Clarkson university included determination of the ionic partition and diffusion coefficients, estimation of single and multiple ion partition coefficients, and anion partition coefficients, at different operating conditions (i.e., pH, and temperature). Impurity removal tests were also conducted using lead electrode and Nafion separator. In addition to Nafion membrane, ceramic membrane also was used for the multiple ion partition and diffusion tests. Partial completion of the diffusion modeling allowed for modeling result to be compared to the experimental data.
Task 2: Field Trials. A proper cell that is a scale-up version of laboratory small-sized cell is still undergoing testing. Therefore, there were no field trials during the reporting period. Upon completion of the cell design modification, the scale up FCMP based cells and field trials will begin during the second-third year of this project. Meanwhile, some limited trials were conducted using a Porous Ceramic Membrane Cell (PCMC?purchased from Hard Chromium Plating Consultants, Cleveland, Ohio). These trials were done in collaboration with in-kind resources provided by Dover Industrial Chrome, Inc., Chicago, IL, and, real time hard chromium plating tanks having trivalent chromium, iron, nickel, zinc and copper as impurities were used. The results of these limited trials will be used as base line data for comparison during future trials.
Task 3: Modeling. A mathematical model was developed at IIT to predict the change of contaminant concentrations with time, and to estimate contaminant fluxes due to migration, diffusion and convection in a laboratory-scale batch electrolysis cell for regeneration of contaminated hard chrome plating baths. The mathematical model was used to estimate process parameters from experimental results, assuming quasi-stationary operation. Ionic mobilities of Cu, Fe, and Ni through the Nafion-117 membrane were found to be 5.4, 1.7, 5.2*10-10 cm2/V.s for Cu, Fe, Ni, respectively.
Future Activities:
Task 1: At IIT, work will be continued in the following directions: (1) completion of the cell design modifications; (2) determination of the metal removal capacity using improved oxygen reduction kinetics and experimental data; and (3) cell scale-up for the field trials (i.e., substitution of plastics with ceramic having impregnated nafion and metal). At Clarkson University, future activities include investigating the effects of mixing intensity on diffusion coefficient measurements, comparison of metal removal efficiency between ceramic and Nafion membranes, investigation of CrIII oxidation, and data analysis of the results obtained.
Task 2: Field trials with scaled up cells at Dover Industrial Chrome, Inc., will continue.
Task 3: Mathematical model refinements will continue at both IIT and Clarkson University to fit the experimental data and to refine the experimental parameters including cell design.
Journal Articles on this Report : 3 Displayed | Download in RIS Format
Other project views: | All 5 publications | 3 publications in selected types | All 3 journal articles |
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Type | Citation | ||
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Ahmed MI, Holsen TM, Selman JR. Chromic acid regeneration process with fuel cell electrode assistance. Part II: Electrochemical characterization, material compatibility and energy consumption. Journal of Applied Electrochemistry 2001;31(12):1389-1394. |
R827125 (2000) |
Exit |
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Ahmed MI, Chang HT, Selman JR, Holsen TM. Electrochemical chromic acid regeneration process: Fitting of membrane transport properties. Journal of Membrane Science 2002;197(1-2):63-74. |
R827125 (2000) |
Exit |
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Ahmed MI, Holsen TM, Selman JR. Electrochemical chromic acid regeneration process with fuel-cell electrode assistance. Part I: Removal of contaminants. Journal of Applied Electrochemistry 2001;31(12):1381-1387. |
R827125 (2000) |
not available |
Supplemental Keywords:
chemical transport, waste reduction, treatment, environmental- electrochemical engineering, analytical and electrochemical methods, monitoring and modeling, midwest, plating industry., Scientific Discipline, Industry Sectors, Air, Sustainable Industry/Business, POLLUTION PREVENTION, cleaner production/pollution prevention, Manufacturing - NAIC 31-33, Environmental Chemistry, Energy, Engineering, Chemistry, & Physics, cleaner production, environmentally conscious manufacturing, electroplating, fuel cell electrode, membrane reactors, energy efficiency, ion plating, contaminant removal, mathematical formulations, metal plating, heavy metals, chromium electroplating baths, ion exchangeRelevant Websites:
http://orca.ocean.washington.edu/ Exit
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.