Modeling column extraction of lead contaminated soils and identification of solid lead phases

摘要: Chelate extraction using ethylenediaminetetraacetic acid (EDTA) and other chelates, has been demonstrated to be an effective method of removal Pb from many contaminated soils. Batch shaker extractions require a small investment time labor compared column extractions. Also, leaching alkaline soils with EDTA problematic due extremely low soil permeability. The first purpose this study was model the by based on batch results. second determine effect addition KOH Ca(Cl){sub 2} K{sub 2}H{sub 2}EDTA solution hydraulic conductivity. A Pb-contaminated sampled abandoned lead-acid battery recycling facility. Both experiments were completed 5 different extract solutions. Addition only did not change amount Ph removed extraction. Lead solubility observed decrease as pH increased KOH. required leach 6.0 L through columns varied 2 33 days. Ca(Cl){submore » and/or resulted in However, diminished because decreased also shorter residence column. conductivity related residual calcium carbonate content, suggesting that dissolution CaCO{sub 3} subsequent production CO{sub gas pores partially responsible for reductions Several solid phases identified Analytical Electron Microscopy (AEM). This observation is consistent experimentally dependence concentration.« less