SELECTION OF A SUITABLE SURFACTANT BASED ON ZETA POTENTIAL FOR USE AS PURGING SOLUTION IN ELECTROKINETIC REMEDIATION OF CADMIUM FROM CADMIUM CONTAMINATED SOIL

摘要

The principal objective of the present work is to assess the behaviour of variations in zeta potential using three different surfactants (anionic, cationic and non-ionic) through batch experiments. Preliminary batch experiments were performed to observe the effects of soil: solution ratio and optimum time required to attain a constant pH. From the results, the optimum soil solution ratio is 20 g/l and the pH of the soil suspension attained constant values after 120-150 min of stirring. Further, the results of influence of surfactant concentration on zeta potential in fresh and cadmium contaminated soils, respectively, show that the zeta potential for anionic surfactants (SDS) lies between -36.14 and -30.19 mV, for cationic (CTAB) surfactant between +35.68 and +34.71 mV and for non-ionic surfactant (Triton X 100) between -32.12 and -29.31 mV at surfactant concentration of 1 M. On the basis of zeta potential, the anionic surfactant (SDS) of concentration 1 M is selected as a better surfactant to be used as purging solution in electrokinetic (EK) remediation of cadmium from cadmium contaminated soil. About 98% cadmium removal is attained in EK remediation of cadmium with SDS as purging solution within 72 h of EK remediation.