Electrokinetic Remediation of Cobalt Contaminated Soil Using Ethanoic Buffer

After kaolin clay was artificially contaminated with Co$^{2+}$ ion, the remediation characteristics were analyzed by the electrokinetic method. Ethanoic buffer was injected in the soil column and $CH_3$COOH was continuously inputted to the cathode reservoir to restrain the pH increase. Since the pH of the cathode side of the soil column was 4.0 initially and increased to only 6.5 after remediation for 43.6 hours, precipitate, Co(OH)$_2$, was not formed in the column. The effluent rate increased with the passage of time and Co$^{2+}$ removal in the column at the initial time were mainly controlled by ion migration. 13.1% of the total amount of Co$^{2+}$ in the soil column was removed in 10 hours, 46.8% of the total Co$^{2+}$ in 20.8 hours, 71.7% of the total Co$^{2+}$ in 30.1 hours, and 94.6% of the total Co$^{2+}$ in 43.6 hours. Meanwhile, residual concentrations in the column calculated by the developed model were similar to those by experiment. experiment.