Coupling Of EK/PRB For The Remediation Of Pentachlorophenol Contaminated Soil And Their Interactive Influence

PCP is a kind of strong toxicity, nondegradable persistent organic pollutant. When PCP enters into the environment, it is mostly distributed in solid matix such as soils. As a research, it is meaningful to investigate remediation technology for PCP remediation.The electrokinetic (EK) removal of pentachlorophenol (PCP) in contaminated soils is difficult because it can be dissociated at different pH along soil column and transported conversely in the region near anode and cathode. In present study, a permeable reactive barrier (PRB) filled with reactive Pd/Fe particles was installed between anode and cathode to reach the dechlorination of PCP when it transported through the PRB. When PRB was installed at the position of 0.3 (x/L, normalized distance from anode), PCP in anode side of PRB could transport through PRB while in cathode side was accumulated near PRB. PCP could be hardly dechlorinated by Pd/Fe in PRB because of the high pH in the compartment. When PRB was installed at the position of 0.5 and PRB pH was conditioned by periodical injection of HAc, 49% of PCP was removed, and 22.9% was recovered as pHenol which was mostly collected in catholyte. The mechanism for PCP removal was proposed as the EK transport of PCP to PRB compartment, complete dechlorination of PCP to pHenol by Pd/Fe in PRB compartment, and subsequent removal of pHenol by electroosmosis. This study proved the EK coupled with Pd/Fe PRB was effective for the remediation of PCP contaminate soil.In the coupled EK/PRB system which was used for the contaminated soil remediation, the cumulative electroosmotic flow was the larest when PRB was installed in the middle. The soil between PRB and anode was weakly acidic, and the soil between PRB and cathode was alkaline, which was conductive to the migration of PCP to PRB. What's more, the pH value of anodic liquid was the lowest which was in favor of maintaining the weakly acidic environment of PRB, so the hydrogenation reduction of PCP was easier to proceed. However, the PRB was severely corroded when it was installed at anode and sodium hydroxide protective film would be formed when PRB was installed at cathode, which would influence its performance. When PRB was installed in the middle of the system, only a small amount of reactive Pd/Fe particles were corroded and no sodium hydroxide protective film was observed, which was optimal for the catalytic degradation of contaminant.