Experimental Study On Remediation Of Heavy Metal Contaminated Clay By Magnetization Eluent Technology And Freeze-Thaw

With the rapid development of social economy,all kinds of productive behavior of people have caused harm to the soil environment,increasing the content of heavy metals in the soil,and then affecting human health.Therefore,how to efficiently and stably repair heavy metal contaminated soil has become a popular focus.Freezing-thawing leaching method can effectively remove heavy metals from soil,but it has problems of low leaching efficiency and long restoration period.Therefore,in order to solve this problem,this paper proposes to improve the repair effect of freezing-thawing leaching on heavy metals by improving the physical and chemical properties of the leaching agent,such as wettability and viscosity,with the help of magnetization eluent technology.In this paper,Cd and Pb contaminated soil was selected as the research object,and EDTA was used as the eluent to carry out the experiment of freeze-thaw synergistic chemical leaching to repair heavy metal contaminated soil.Firstly,magnetize the eluent EDTA and analyze the change law of physical and chemical properties.Secondly,the removal efficiency of magnetized eluent for heavy metals was analyzed by oscillation leaching test and freeze-thaw leaching column test in laboratory,and the changes of heavy metal speciation before and after restoration.The feasibility of magnetization technology to improve the remediation efficiency of heavy metal contaminated clay by freezingthawing leaching was discussed,the following conclusions are drawn:(1)The viscosity,contact Angle and surface tension of magnetized EDTA decrease,while the conductivity and p H increase.Among them,the changes of 0.05mol/L EDTA concentration are more obvious than 0.1 and 0.2mol/L EDTA concentration after magnetization,and the viscosity,surface tension and contact Angle decrease by 6.20%,11.15% and 9.46%,respectively.The increase of p H value avoids causing soil acidity.(2)Magnetized EDTA can increase the frost heaving and water absorption of clay,and the water absorption can increase 39.85%,and the removal rate of heavy metal Cd and Pb can increase 27.13% and 8.13% respectively.(3)The conversion ability of heavy metals to the active state of the replenished magnetization eluent is weakened,but the conversion ability to the stable state is enhanced.(4)Magnetization eluent technology provides a more efficient,low-cost and environmentally friendly idea for the leaching and remediation of heavy metal contaminated clay.The paper has 48 pictures,6 tables,and 164 references.