REMOVAL OF CADMIUM (II) FROM SATURATED KAOLINITE BY THE APPLICATION OF ELECTRICAL-CURRENT

The fundamentals of electrokinetic remediation (the removal of contaminants from soils by the application of electrical current across electrodes inserted in a soil mass) are presented and the findings of recent studies are reviewed. An improved theoretical formalism is presented for conduction phenomena under electrical currents. Predictions of effluent pH using this model compared excellently with the results of one-dimensional experimental studies. The results of four one-dimensional tests conducted to assess the removal of 99-114 mug/g of Cd(II) loaded on kaolinite specimens are presented. The flow conditions, chemistry, efficiency of removal and energy expenditure in these tests are evaluated. Cd(II) was removed from the kaolinite specimens by 90-95%. It was deposited close to the cathode and on the cathode due to the basic environment and electrodeposition. The energy expenditure in these tests was 50-106 kW h/m3 of soil processed. The test results also showed that when the initial pH in the specimen is low, high removal rates are achieved by electrical migration rather than electro-osmotic flow.