Modification Of Kaolin And Its Effect Of Remediation Cd Contaminated Soil

China is in the stage of industrialization and urbanization.Water pollution and contaminated soil of heavy metal are prominent,which seriously affect the ecological environment and human health.This paper takes kaolin as the research object,through modified kaolin,systematically studies the stabilization ability of modified kaolin to Cd pollution and its effect on Chinese cabbage growing in Cd-contaminated soil by experiment of adsorption,desorption and pot.The main results are as follows:（1）Modification of kaolin occurs only on the surface of kaolin,but has no effect on the crystal of kaolin.The specific surface area of kaolin is improved by inorganic modification and organic-inorganic combination modification.The specific surface area of kaolin increased from 9.22 m²·g^-1 to 14.25 m²·g^-1and 11.43 m²·g^-1by inorganic modification and organic-inorganic combination modification,respectively.The pore size increased from 3.03 to 3.82 and 3.81 nm.（2）Compared with other modified kaolin,inorganic modified kaolin has the strongest adsorptive capacity for Cd²⁺and the lowest desorption rate and the best adsorption stability.The adsorption capacity of Cd²⁺was inorganic modified kaolin（Fe-K）>organic-inorganic combined modified kaolin（Fe-O-K）>organic modified kaolin（O-K）>kaolin,and the desorption rate was kaolin>Fe-O-K>O-K>Fe-K>Fe-K kaolin and three kinds of modified kaolin all accorded with Langmuir isothermal adsorption model and quasi-second-order kinetics model.（3）Compared with the control,the application of Fe-K at 1%,2%and 3%could stabilize Cd in soil,reduce the accumulation of Cd in Brassica chinensis L.,and increase biomass and stress resistance at low and medium dosages.Fe-K can increase soil pH,decrease the proportion of weak acid extractable form of Cd in soil,increase the proportion of residual form of Cd in soil,and soil conditioner Fe-K can reduce the accumulation of Cd in the shoot and root parts of Brassica chinensis L..The biomass of Brassica chinensis L.can be significantly increased with the addition of Fe-K 1%and 2%,respectively,from 0.11g to 0.29 g and 0.25 g.In conclusion,inorganic modification can improve the ability of kaolin to adsorb Cd and stabilize soil Cd.Low and medium dosage of inorganic modified kaolin can improve the ability of Brassica chinensis L.to alleviate soil Cd stress and increase its biomass.Fe-K is the best remediation material for Cd contamination in soil with 1%addition.