Enhanced removal of cadmium from alkaline soil by electromigration
Rakesh K. Srivastava, Ram P. Tiwari and P. Bala Ramudu

High-buffering expansive soil, characterized as high cation-exchange capacity (CEC) soil, and rich in calcium carbonate (2.5%) was collected in the field, and was spiked with cadmium and treated using the electrokinetic (EK) technique in order to investigate the feasibility of enhanced electrokinetic remediation using chelating agents and surfactant. A 1-D experimental set-up was developed, and tests were performed with various flushing agents, such as de-ionized (DI) water (non-enhanced), ammonium citrate (AC), sodium citrate (SC) and a non-ionic surfactant Tween-20 (enhanced) purged at the anode end. The applied voltage was 35 V DC, and the duration of the test-run was 120 hours. From the experimental results, it was observed that the efficiency of electrokinetic extraction was significantly influenced by the pH of the soil. Enhanced cadmium removal was observed with alkali ammonium citrate during the remediation process, in comparison to other desorbing agents. Variations in the concentration of the soluble form of cadmium were observed by conducting extrac-tion studies on EK-treated soils, with de-ionized water as a control, to investigate cadmium migration during the EK process. X-ray fluorescence (XRF) and X-ray diffraction (XRD) analysis were per-formed to assess micro-morphological changes in the soil during the EK process. It was observed that the mineralogical compositions were moderately affected by the electrokinetic process, but overall the minerals remained the same.

Key words: cadmium, chelating agents, desorption, electrokinetic remediation, minerals, sorption, surfactant

Land Contamination & Reclamation, 16 (3), 191-212

DOI 10.2462/09670513.873

© 2008 EPP Publications Ltd 

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