The effect of citric acid addition in electro-kinetic remediation of chromium-nickel combined contaminated soil

The effects of electro-kinetic remediation time on soil current, pH, electrical conductivity and Cr-Ni removal rate were studied to determine the optimal treated time.Orthogonal desorption experiments are then conducted to study the effect of cathode liquid and the concentration on electro-kinetic remediation of chromium-nickel combined contaminated soil.The results showed that, among four types of cathode liquid including EDTA, citric acid, tartaric acid and acetic acid, citric acid is the most effective cathode liquid with 0.1 mol/L of optimal concentration.Under the optimum experimental conditions, the removal rate of chromium can reach 61.76%, but the rate of nickel is only 16.29%.This may be due to the fact the optimum treated time should be extended after the addition of citric acid used as cathode liquid.