CATHOLYTE-CONDITIONING ENHANCED ELECTROKINETIC REMEDIATION OF Co AND Pb POLLUTED SOIL

Abstract

The feasibility of catholyte-conditioning to enhance the electrokinetic (EK) remediation of cobalt and lead polluted soil has been investigated in this study. Electrokinetic experiments were conducted using an EK cell 10 cm in width, 10 cm in height, and 50 cm in length. Plate type electrode of graphite was used as electrode material. Two experiments were conducted under constant voltage condition (2 V/cm). The pH values of the soil significantly affect the removal of Co and Pb ions. Due to electrolysis reaction, soil pH increases near the cathode and without pH conditioning, metals precipitate as hydroxides. This problem is solved by the addition of nitric acid (0.1N) in the catholyte compartment. Significant movement of metals was observed through the soil with high removal efficiency. Results showed that catholyte conditioning using nitric acid increased the removal of cobalt and lead from the soil and, consequently, the maximum removal achieved was 73.84% and 62.88% for cobalt and lead, respectively. These EK tests indicate that the increased experimental time induced a higher removal efficiency of cobalt and lead. The results suggest that longer treatment periods will result in further transport of cobalt and lead in the sample. Also, it indicated that the highest quantities of cobalt and lead moved towards the catholyte, particularly at upper 5 cm. On the basis of the experimental results, we conclude that the electrokinetic remediation, using 0.1N HNO3 as catholyte-conditioning, is suitable for extracting cobalt and lead from polluted soil.