Electrokinetic Remediation And The Reinforcement For The Cadmium Pollution In The Soil

Soil heavy metal pollution has become one of the most serious environmental problems of global concerns. Since the accumulation of heavy metal in soil could not be found easily and not biodegradable, the heavy metal in the soil not only destroy the microbial community and population structure in soil, restrain the grown of crop, but also pose risks and hazards to human health through. The heavy metal pollution in farmland in our country is serious, but the repair technologies are flawed. In this study, the electrokinetic remediation was used to solve the problem of heavy metal in soil, since the method is fast and efficient.Humin is the component of humic substances that is recalcitrant to extraction by either strong bases or strong acids, which contains a variety of functional groups that may combine with heavy metal ions. The present study employed humin as an adsorbent to investigate the efficacy of a remediation strategy under the effects of humin-enhanced electrokinetics. Humin was placed in close proximity to the cathode in the form of a package (such that it could be easily removed following the experiments), to determine whether a target pollutant (cadmium) might be completely removed from soil. Acetic acid-sodium acetate was selected as the electrolyte for these experiments, which was circulated between the two electrode chambers via a peristaltic pump, in order to control the pH of the soil.The results indicated that remediation efficiency increased with time, and when the remediation duration was extended to 240 hours, the removal of acid extractable Cd (â…¡) could attain up to 43.86% efficiency, and the adsorption of the heavy metal within the humin was 86.15mg/kg. Further, the recycling of the electrolyte exhibited a good control of the pH of the soil. When comparing the pH of the soil with the circulating electrolyte during remediation, in contrast to when it was not being recycled, the pH of the soil at the anode increased from 3.89 to 5.63, whereas the soil at the cathode decreased from 8.06 to 7.10. This indicated that the electrolyte recycling had the capacity to stabilize the pH of the soil.Effect of addition of low-molecular-weight organic acids (tartaric,oxalic acid)in soil on the electrokinetic remediation(EK) of the contaminated soil by Cadmium was study in laboratory-scale experiments. The results showed that the low-molecular-weight organic acids significantly enhanced the removal of Cd (â…¡). The removal of acid extractable of Cd (â…¡) could attained up to 67.07%. And the efficiency was different since the concentrations of the low-molecular-weight organic acid were different:the efficiency was decreased when the increase of the concentrations.