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Electrokinetic remediation of arsenate spiked soil assisted by CNT-Co barrier—The effect of barrier position and processing fluid

Authors
Journal
Journal of Hazardous Materials
0304-3894
Publisher
Elsevier
Publication Date
Volume
171
Identifiers
DOI: 10.1016/j.jhazmat.2009.06.059
Keywords
  • Arsenic
  • Carbon Nanotube
  • Electrokinetic
  • Nano-Composite
  • Soil Remediation

Abstract

Abstract An enhanced electrokinetic (EK) remediation process coupled with permeable reaction barrier (PRB) of carbon nanotube coated with cobalt (CNT-Co) has been investigated for As(V) removal from soil under potential gradient of 2.0 V/cm for 5 days treatment. Results showed that removal efficiency of As(V) was greater than 70% in EK/CNT-Co system with EDTA as processing fluid, which was enhanced by a factor of 2.2 compared to EK system and EK/CNT systems. A better removal performance in EK/CNT-Co system was attributed to higher sorption of As(V) onto CNT-Co than onto CNT. Removal of As(V) in EK/CNT-Co system was mainly contributed by surface sorption on CNT-Co rather than by EK process. The surface characteristics of CNT-Co, which was qualified by SEM coupled with EDS, were clearly confirmed that arsenic was adsorbed on the passive layer surface. Among EK processes, As(V) removal was dominated by electroosmosis flow and electromigration in EK/CNT-Co system with groundwater and EDTA as processing fluid. An investigation with sequential extraction revealed that As(V) associated with soils was considerably shifted from strong binding forms, i.e., Fe-Mn oxide, organic, and residual, to weak binding forms, i.e., exchange and carbonate, after EK/CNT-Co treatment.

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