重金属Cd污染土壤的电动修复研究

发布时间：2018-10-18 16:45

【摘要】：重金属污染土壤的电动修复技术是通过将污染土壤置于电解槽中,然后在电解槽两端施加一直流电压,使得重金属污染物在土壤颗粒表面解吸并进入土壤孔隙液中,最后重金属在电场中进行定向迁移并从土壤中去除的一种土壤修复技术。本文以重金属Cd污染土壤作为电动修复试验研究对象,对模拟重金属Cd污染红壤以及实际重金属Cd污染土壤进行电动修复试验。研究了不同提取剂对模拟重金属Cd污染红壤提取率的影响以及不同阴极电解液,不同修复电压梯度,不同电动修复时间对模拟重金属Cd污染红壤的电动修复的影响,在模拟重金属Cd污染红壤的电动修复过程中找到针对重金属Cd污染土壤最佳的电动修复参数。运用该电动修复参数对实际重金属Cd污染土壤进行了电动修复试验,进一步验证最佳电动修复参数。试验结果如下:(1)在模拟重金属Cd污染红壤的提取试验中,柠檬酸作为提取剂可以利用其络合能力将污染土壤中的重金属Cd有效提取出来,当柠檬酸浓度为0.1mol/L时,模拟重金属Cd污染红壤中重金属Cd的提取量最高可达746.15mg/kg,具有较好的提取效果;(2)在模拟重金属Cd污染红壤的电动修复过程中,阴极电解液的选取对阴极电解室pH的变化有直接的影响,最终可以影响到土壤中重金属Cd的去除效果,试验表明当选用0.1mol/L的Fe(NO3)3作为电动修复的阴极电解液时可以对模拟重金属Cd污染红壤达到较理想的修复效果;(3)当选用1.5v/cm的电压梯度对模拟重金属Cd污染红壤进行电动修复时,土壤中重金属Cd的平均去除率达到90%以上;(4)当对模拟重金属Cd污染红壤进行电动修复时,电动修复时间为10d可以达到较好的修复效果,在此电动修复时间下,既确保了模拟重金属Cd污染红壤的电动修复效率又进一步减少了能量的消耗;(5)利用得到的最佳电动修复参数对实际重金属Cd污染土壤进行电动修复试验,试验结果表明实际土壤中重金属Cd的去除率达到了 55%以上,显示了良好的修复效果,表明该电动修复参数对重金属Cd污染土壤的修复具有普遍适用性,在实际重金属Cd污染土壤中有很多复杂的因素影响着电动修复的效果,如本试验中所用的土壤为具有强酸性缓冲能力的碱性土壤,由于pH较高,电动修复过程中土壤颗粒表面吸附的重金属Cd不能有效的解吸并在电场作用下进行有效电迁移,加入的柠檬酸饱和溶液通过与重金属Cd的络合作用可以提高重金属Cd的去除率。
[Abstract]:The electrokinetic remediation technique for heavy metal contaminated soil is to desorb the contaminated soil on the soil particle surface and enter the soil pore fluid by placing the contaminated soil in an electrolytic cell and then applying a constant current voltage at the two ends of the electrolytic cell. Finally, a soil remediation technique for the directional migration of heavy metals in the electric field and their removal from the soil. In this paper, the heavy metal Cd contaminated soil was used as the research object of electric remediation experiment. The simulated heavy metal Cd contaminated red soil and the actual heavy metal Cd contaminated soil were treated with electric remediation test. The effects of different extractants on the extraction rate of simulated heavy metal Cd contaminated red soil and the effects of different cathode electrolyte, different repair voltage gradient and different electric repair time on the electric remediation of simulated heavy metal Cd contaminated red soil were studied. The best electrokinetic remediation parameters for heavy metal Cd contaminated red soil were found in the process of simulating heavy metal Cd contaminated red soil. The electric remediation parameters were used to test the actual heavy metal Cd contaminated soil in order to verify the best electric remediation parameters. The results are as follows: (1) in the extraction experiment of simulated heavy metal Cd contaminated red soil, citric acid can be used as extractant to extract the heavy metal Cd from contaminated soil effectively, when the citric acid concentration is 0.1mol/L, The extraction amount of heavy metal Cd from red soil contaminated by simulated heavy metal Cd can reach 746.15 mg / kg, which has better extraction effect. (2) in the process of electric remediation of simulated heavy metal Cd contaminated red soil, The selection of cathode electrolyte has a direct effect on the change of pH in cathode electrolytic chamber, and finally affects the removal effect of heavy metal Cd in soil. The results show that Fe (NO3) 3 of 0.1mol/L can be used as cathodic electrolyte to restore the red soil contaminated by Cd. (3) when the voltage gradient of 1.5v/cm is used to restore the red soil contaminated by Cd, the simulated heavy metal Cd contaminated red soil can be repaired by electrokinetic method. The average removal rate of heavy metal Cd in soil was more than 90%. (4) when the simulated heavy metal Cd contaminated red soil was repaired by electric method, the electric repair time of 10 days could reach a better effect. It not only ensures the electric recovery efficiency of simulated heavy metal Cd contaminated red soil, but also reduces the energy consumption. (5) using the optimum electric remediation parameters, the actual heavy metal Cd contaminated soil can be remedied by electric method. The experimental results show that the removal rate of heavy metal Cd in soil is over 55%, which indicates that the electric remediation parameters are applicable to the remediation of heavy metal Cd contaminated soil. In the actual heavy metal Cd contaminated soil, there are many complicated factors affecting the effect of electric remediation. For example, the soil used in this experiment is alkaline soil with strong acid buffer capacity, because of the high pH, The adsorption of heavy metal Cd on the surface of soil particles could not be effectively desorbed and effectively electromigrated under the action of electric field during the process of electrokinetic remediation. The addition of saturated citric acid solution could improve the removal rate of Cd by complexing with heavy metal Cd.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X53

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