Investigation of electrokinetic method efficiency in the removal of mercury from contaminated clayey soil

Electrokinetic is restoration method of contaminated soils using electric field. This method is used to decontaminate of heavy metals, anions and polar organic compositions from the soil. In this study, mercury removal efficiency from the clayey soil with 2/1 weight ratio of kaolin to sand is considered using this method and then optimum removal conditions are determined. The Kaolin provides suitable conditions to evaluate the electrokinetic method efficiency due to intense absorption of pollutant and suitable simulation of the contaminated site. In this research, total mercury concentration of the soil was 800 mg/kg and tests duration was 32 days. Experiments were performed in two voltage gradients of 1.0 and 1.5 VDC/cm and employing 0.1 M Na-EDTA, 0.1 & 0.4 M KI solutions and distilled water as catholyte. The results showed that the best efficiency, 99.03%, was achieved when the 0.4 M KI solution was employed with the 1.0 VDC/cm voltage gradient. Then, the profiles of electrical current, pH of anode and cathode reservoirs and pH, water content and electrical conductivity of soil were plotted and were discussed.