Abstract
In Application of electrokinetic soil remediation to the heavy metals contaminated soils, the acidification might cause dissolution of part of the solid matrix, and so it is desirable to perform the soil treatment at neutral pH. However, the solubility of most heavy metals is significantly reduced at elevated pH values. The solubility of metals can be enhanced by adding reagents that form metal complexes. Apart from efficacy as metal extractants, complexing agents need also to be rated for safety of use. Biodegradability is of importance because treated soils always contain residual agents that may, upon soil reuse in the field, result in actual metal mobilization and transport to groundwater. It appears therefore essential for these residual agents to be rapidly biodegraded. This is even more important for in-situ soil flushing operations. In this research, the biodegradable chelating agents [S,S]-ethylenediaminedisuccinic acid (EDDS) and N,N-dicarboxymethyl glutamic acid (GLDA) were investigated for their applicability for the removal of lead from soils by electrokinetic processing. The removal efficiency of lead from soils was improved with increase in the concentration of EDDS and the applied electric field strength. It was also found that the concentration of EDDS has a strong effect on the removal efficiency of lead from soils compared with the electrical field strength at the range from 10 V and 20 V. And also, the removal efficiency of lead using platinum-coated titanium used as electrodes increased compared with graphite and iridium dioxide-coated titanium as electrode. Meanwhile, the removal efficiency of lead with GLDA was superior to that with EDDS. However, the high viscosity of GLDA significantly affected the removal efficiency of lead.
