Treatment of Soil Polluted with Cadmium by Electrokinetics with Solar Power: Effects of Electrolyte

The research aims to analyse the treatment possibility of Cd-polluted soil using electrokinetics driven by solar power in comparison with driving by direct current power. Meanwhile, the effects of electrolyte on electrokinetics were investigated. Five runs of electrokinetics were carried out using different electrolytes and energy sources. Experimental results showed that the combined application of electrokinetics and solar power was effective for the treatment of Cd-polluted soil and electrolyte-affected Cd removal significantly. Run B (direct current power, KNO 3 as anolyte, HCl as catholyte, the removal efficiency of Cd was 91.5%) had the highest removal efficiency in all runs because of stable working voltage, the highest electro-osmotic flow, and the advantages of using HCl as catholyte which could dissolve Cd(OH) 2 of the cathode region and reduce focusing phenomena. In run C (solar power, KNO 3 as anolyte, HCl as catholyte, the removal efficiency of Cd was 84.21%), replacing direct current power with solar power could not only reduce energy consumption but also provide better efficiency in Cd removal under fine weather conditions. Meanwhile, electrokinetics changed the chemical forms of Cd in soil. After electrokinetics, Cd of soil existed mainly in less toxic residual fraction.