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ELECTROCHEMICAL DEGRADATION OF PERSISTANCE POLLUTANTS IN GROUNDWATER AND SEDIMENTS
Citation:
AL-ABED, S. R. ELECTROCHEMICAL DEGRADATION OF PERSISTANCE POLLUTANTS IN GROUNDWATER AND SEDIMENTS. Presented at Pacifichem Conference, Honolulu, HI, December 15 - 20, 2005.
Impact/Purpose:
to present information
Description:
Electrochemical Degradation (ECD) utilizes redox potential at the anode and the cathode to oxidize and/or reduce organic contaminants. ECD of environmentally persistence pollutants such chlorinate solvents, PCBs, and PAHs, although theoretically possible, has not been experimentally proven. ECD of these compounds follows different mechanisms such as low redox potential and ample electrons available at the cathode suggest and oxidation at the anode. We tested ECD of trichloroethylene (TCE), and 2-chlorobiphenyl (PCB) using granulier graphite electrodes in a mixed batch reactor under an applied voltage of 10V. We also tested PCB adsorbed on sediments in a reactor with electrode chambers separated by Nafion membrane. The focus of our experiments is to identify and quantify the reduction rates of TCE and PCB. In experiments with an initial TCE voltage of 10V, compounds detected from TCE dechlorination were chloride in the solution, ethane and a minimal amount of methane and ethane in the headspace gas. The mass balance of chlorine showed that amount of chloride converted from TCE was much less than the amount of chlorine in TCE that had been reduced. The chloride yield decreased as a higher cell voltage was applied. PCB was effectively dechlorinated in electrochemical reactors using cathodes of packed granular-graphite. PCB dechlorination in a membrane reactor using Pd modified granular graphite cathode resulted in about 88% of the initial 2-chlorobiphenyl (2-Cl BP) in the solution dechlorinated to biphenyl (BP). Our results confirmed the effectiveness of ECD to dechlorinate TCE and PCB with the potential of using this technology to remediate such as PAHs, fuels, and arsenic in contaminated sediments and groundwater.