Electrokinetic migration and removal of lead pollutants in kaolin
摘要
The artificially prepared lead-contaminated kaolin is used as the research object with a new type of electrokinetic geosynthetics (EKG) as electrode to study the mechanism of electrokinetic remediation of lead-contaminated kaolin. Two different electrokinetic remediation methods are used. The effects of different additives on the removal efficiency of heavy metals in contaminated soil and the differences of the two repair methods are studied by analyzing the current, soil pH and the existing forms of lead elements. The results show that the later stage of current variation for the renewal electrolyte method of electrokinetic remediation tests has a significant decline pattern, while that for the electrolyte cycle method has a slightly fluctuating pattern instead. For the remediation of lead-contaminated soil, the additive of the acetic is more effective to the removal of lead than that of the citric. Citric acid and lead ions are easy to form substances that are difficult to ionize, which is poor for lead migration. The ethylenediaminetetraacetic acid disodium can complex with most lead ions to form complex ions. The hydrogen ion and hydroxide radical produced by electrolytic water can be well controlled by circulating cathode and anode electrolyte with peristaltic pump, so as to reduce their impact on the soil pH and heavy metal speciation. In the tests, the removal of heavy metals by ion diffusion and scouring caused by the electrolyte circulation is less than 10%. This further illustrates the effectiveness of the electrokinetic method in removing heavy metal contaminants from soil.