Publications (15) View all
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Article: Partitioning of hexachlorobenzene in a kaolin/humic acid/surfactant/water system: combined effect of surfactant and soil organic matter.
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ABSTRACT: Understanding the combined effect of soil organic matter (SOM) and surfactants on the partitioning of hydrophobic organic compounds in soil/water systems is important to predict the effectiveness of surfactant-enhanced remediation (SER). In the present study we investigate the partitioning of hexachlorobenzene (HCB) within a humic acid (HA)-coated kaolin/Triton X-100 (TX100)/water system, with special emphasis on the interaction between TX100 and HA, and their combined effect on HCB sorption. HA firstly enhanced then suppressed TX100 sorption to kaolin as the amounts of HA increased, while the addition of TX100 led to a consistent reduction in HA sorption. In the HA-coated kaolin/TX100/water system, TX100 played a primary role in enhancing desorption of HCB, while the role could be suppressed and then enhanced as HA coating amounts increased. Only at HA coating above 2.4%, dissolved HA outcompeted clay-bound HA for HCB partitioning, resulting in dissolved HA enhanced desorption. The presence of dissolved HA at these conditions further promoted the effectiveness of TX100 enhanced desorption. Despite a reduced TX100 sorption to clay was achieved due to the presence of dissolved HA, the effect on HCB desorption was comparatively slight. A reliable cumulative influence of HA and TX100 on HCB desorption was observed, although HCB desorption by HA/TX100 mixed was less than the sum of HA and TX100 individually. Our study suggests that for soils of high organic contents, the combined effect of SOM and surfactants on HOCs desorption can be applied to improve the performance of SER.Journal of hazardous materials 09/2011; 196:79-85. · 4.14 Impact Factor -
Article: A combination of electrokinetics and Pd/Fe PRB for the remediation of pentachlorophenol-contaminated soil.
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ABSTRACT: Electrokinetic (EK) remediation of pentachlorophenol (PCP)-contaminated soil is difficult because PCP dissociates at different pH values along soil column and shows different transport behaviors near anode and cathode. In the 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 during its EK movement. When PRB was installed at the position of 0.3 (normalized distance from anode), PCP in the section from anode to PRB could transport through PRB, while PCP in the section from cathode to PRB was accumulated near PRB. PCP was hardly dechlorinated by PRB wherein high pH was reached. When PRB was installed at the position of 0.5 and the pH in the PRB was decreased 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 of PCP removal was proposed as the EK movement of PCP into the PRB compartment, the complete dechlorination of PCP to phenol by Pd/Fe in the PRB compartment, and the subsequent removal of phenol by electroosmosis. This study proved that the combination of electrokinetics and Pd/Fe PRB was effective for the remediation of PCP-contaminated soil.Journal of contaminant hydrology 03/2011; 124(1-4):99-107. · 2.01 Impact Factor -
Article: Remediation of hexachlorobenzene contaminated soils by rhamnolipid enhanced soil washing coupled with activated carbon selective adsorption.
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ABSTRACT: The present study investigates the selective adsorption of hexachlorobenzene (HCB) from rhamnolipid solution by a powdered activated carbon (PAC). A combined soil washing-PAC adsorption technique is further evaluated on the removal of HCB from two soils, a spiked kaolin and a contaminated real soil. PAC at a dosage of 10 g L(-1) could achieve a HCB removal of 80-99% with initial HCB and rhamnolipid concentrations of 1 mg L(-1) and 3.3-25 g L(-1), respectively. The corresponding adsorptive loss of rhamnolipid was 8-19%. Successive soil washing-PAC adsorption tests (new soil sample was subjected to washing for each cycle) showed encouraging leaching and adsorption performances for HCB. When 25 g L(-1) rhamnolipid solution was applied, HCB leaching from soils was 55-71% for three cycles of washing, and HCB removal by PAC was nearly 90%. An overall 86% and 88% removal of HCB were obtained for kaolin and real soil, respectively, by using the combined process to wash one soil sample for twice. Our investigation suggests that coupling AC adsorption with biosurfactant-enhanced soil washing is a promising alternative to remove hydrophobic organic compounds from soils.Journal of hazardous materials 02/2011; 189(1-2):458-64. · 4.14 Impact Factor -
Article: Remediation of a hexachlorobenzene-contaminated soil by surfactant-enhanced electrokinetics coupled with microscale Pd/Fe PRB.
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ABSTRACT: Treatment of soils contaminated with chlorinated hydrophobic organic compounds (CHOCs) remains a challenge for environmental scientists worldwide. In this study surfactant-enhanced electrokinetics (SEEK) was coupled with permeable reactive barrier (PRB) composed of microscale Pd/Fe to treat a hexachlorobenzene (HCB)-contaminated soil. A nonionic surfactant, Triton X-100 (TX-100), was selected as the solubility-enhancing agent. Five bench-scale tests were conducted to investigate the performance of EK-PRB on HCB removal from soils. Results showed that the HCB removal was generally increased by a factor of 4 by EK coupled with PRB compared with EK alone (60% versus 13%). In the EK-PRB system, HCB was removed from soil through several sequential processes: the movement driven by electroosmotic flow (EOF) in the anode column, the complete adsorption/degradation by the reactive Pd/Fe particles in PRB, and the consequent movement by EOF and probable electrochemical reactions in the cathode column. TX-100 was supposed to be a superior enhancement agent for HCB removal, not only in the EOF movement process but also in the Pd/Fe degradation process. This study indicates that the combination of SEEK and Pd/Fe PRB is efficient and promising to remove CHOCs from contaminated soils.Journal of hazardous materials 12/2010; 184(1-3):184-90. · 4.14 Impact Factor -
Article: Hydroxypropyl-beta-cyclodextrin enhanced electrokinetic remediation of sediment contaminated with HCB and heavy metals.
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ABSTRACT: This work aimed to evaluate hydroxypropyl-beta-cyclodextrin (HPCD) enhanced electrokinetic (EK) remediation of aged sediment contaminated with hexachlorobenzene (HCB) and heavy metals (Zn and Ni) in bench-scale. Deionized water, 5 and 20% HPCD were used as anodic flushing solutions, respectively, with constant voltage gradient of 1.0 V cm(-1). The experimental results showed that HCB migration and removal from sediments was significantly affected by HPCD concentrations and cumulative electroosmotic flow (EOF). In test with deionized water, only 7% of HCB was removed with 4.0 pore volumes (PVs) of EOF, while 15-26% of HCB was removed with 2.5-4.5 PVs using 5% HPCD solution. With 20% HPCD solution, nearly 40% of HCB removal efficiency achieved with 2.6 PVs. For Zn and Ni, the mobilization was greatly dependent upon sediment pH. In all tests, heavy metals migrated from anode to cathode, and accumulated near cathode due to the high pH, with little removal efficiency. This study indicated that EK process combined with HPCD flushing and pH buffering was a good alternative for HCB removal from sediments, and other enhancement was needed for heavy metals removal.Journal of hazardous materials 11/2009; 176(1-3):306-12. · 4.14 Impact Factor
