Enhanced electrokinetic remediation of high sorption capacity soil

Abstract

In unenhanced electrokinetic remediation of metals, electrolysis reactions at the cathode generate a high pH medium that results in metal precipitation and immobilization in the soil. Different enhancement procedures could be utilized at the electrodes to prevent or hinder the generation and transport of this alkaline medium into the soil. This study investigates the feasibility of enhanced extraction of metals from high sorption capacity soils by the use of acetic acid to neutralize the cathode electrolysis reaction and also the use of an ion selective (Nafion TM) membrane to prevent back-transport of the OH − generated at the cathode. Synthetic soil samples spiked with lead were used in the testing. Synthetic soils were a mixture of 40% illite, 8% kaolinite, 5% Na-montmorillonite and 47% fine sand representing an illitic deposit. The results demonstrate the feasibility of extracting lead from the deposit. Acetic acid and Nafion enhancement resulted in better removal efficiencies and lead electrodepositions at the cathode compared to unenhanced tests. However, higher energy expenditure and longer processing periods were required when compared to enhanced extraction of lead from kaolinite. Acetic acid tests required less energy than membrane tests.