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Reductive dehalogenation of gas-phase chlorinated solvents using a modified fuel cell
Z Liu1, R G Arnold, E A Betterton
1Department of Chemical and Environmental Engineering, The University of Arizona, Tucson 85721, USA.
Environmental Science & Technology
|November 23, 2001
Summary
This study demonstrates a modified fuel cell effectively removes chlorinated alkanes and alkenes from gas streams. Optimal performance was achieved by controlling cathode conditions and temperature, showcasing a promising method for environmental remediation.
Area of Science:
- Environmental Chemistry
- Electrochemistry
- Chemical Engineering
Background:
- Chlorinated organic compounds pose significant environmental and health risks.
- Effective methods for the reductive dehalogenation of volatile organic compounds are crucial for remediation.
Purpose of the Study:
- To investigate the reductive dehalogenation of various chlorinated alkanes and alkenes using a modified fuel cell.
- To identify key operational parameters influencing fuel cell performance for dehalogenation.
Main Methods:
- Utilized a modified fuel cell reactor for gas-phase dehalogenation of CCl4, CHCl3, PCE, and TCE.
- Systematically varied cathode material, electric potential, temperature, O2 concentration, and cathode condition.
- Analyzed reaction kinetics, conversion rates, and half-lives under different conditions.
Main Results:
- Achieved high single-pass conversion rates (approx. 90% for CCl4 at 70°C and -0.4 V).
- Demonstrated first-order kinetics for TCE with half-lives under 1 second.
- Observed that CCl4 transformed faster than CHCl3, and TCE faster than PCE.
- Identified detrimental effects of O2 presence and cathode fouling (HCl accumulation).
- Showed performance restoration by stream modification or polarity reversal.
Conclusions:
- Modified fuel cells offer an efficient pathway for gas-phase reductive dehalogenation of chlorinated compounds.
- Optimizing temperature, electric potential, and cathode condition is vital for maximizing conversion efficiency.
- The system shows potential for treating volatile organic compounds, with strategies identified to mitigate performance degradation.