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

The fundamentals of electrokinetic remediation (the removal of contami nants from soils by the application of electrical current across elect rodes inserted in a soil mass) are presented and the findings of recen t studies are reviewed. An improved theoretical formalism is presented for conduction phenomena under electrical currents. Predictions of ef fluent pH using this model compared excellently with the results of on e-dimensional experimental studies. The results of four one-dimensiona l tests conducted to assess the removal of 99-114 mug/g of Cd(II) load ed on kaolinite specimens are presented. The flow conditions, chemistr y, efficiency of removal and energy expenditure in these tests are eva luated. 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 te sts 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 a re achieved by electrical migration rather than electro-osmotic flow.