Near-anode focusing phenomenon caused by the high anolyte concentration in the electrokinetic remediation of chromium(VI)-contaminated soil.
The effects of the concentration and the low pH value of anolyte on the electrokinetic remediation (EKR) of chromium-contaminated soil were investigated using chromium-spiked kaolin-gypsum soil. Results of visual observation and X-ray fluorescence analysis show that high anolyte concentrations could cause an ion-induced potential gradient well trapping effect on the soil near the anode, and consequently cause a focusing phenomenon (FP) without chemical precipitation. This FP significantly prolonged the remediation duration and reduced chromium removal. The low pH value of soil aggravated the FP, resulting in a quasi-dead zone near the anode caused by the reduction in soil resistance, rather than the adsorption of chromium (VI) ions. The high anolyte concentration also resulted in high energy consumption. The FP and low pH value collectively decreased the energy efficiency by more than 96%. This kind of FP can be predicted via the online monitoring of the potential gradient profiles of the soil between the electrodes in the EKR.
School of Resources and Environmental Science, Chongqing University, Chongqing, 400030, PR China. lidongbayan@cqu.edu.cn
Dong
D
Li
Zhen
Z
Xiong
Yang
Y
Nie
Yuan-Yuan
YY
Niu
Li
L
Wang
Yuan-Yuan
YY
Liu
D002133:Calcium Sulfate / Q000737:chemistry; D002857:Chromium / Q000737:chemistry*; D004566:Electrodes; D004572:Electrolysis; D052918:Environmental Restoration and Remediation / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D007616:Kaolin / Q000737:chemistry; D007700:Kinetics; D012989:Soil Pollutants / Q000737:chemistry*
D012989:Soil Pollutants; D002857:Chromium; C074702:chromium hexavalent ion; D007616:Kaolin; D002133:Calcium Sulfate