Investigation Of Contaminant Transport Properties Of Polymer-modified Bentonite Barrier Material

For industrial contaminated sites,vertical barriers are often used to control the migration of pollutants in soil and groundwater.Bentonite is a common material in vertical partition wall because of its good expansibility.In order to improve its impermeability and retard the migration of pollutants,this paper proposes to use acrylic acid monomer to modify bentonite by organic polymerization,and tests the hydraulic conductivity of polymer modified bentonite in high salt environment（>3%）.The adsorption performance of bentonite for characteristic pollutants in industrial contaminated sites was studied,and the factors influencing the diffusion of pollutants in bentonite barrier materials were studied,the main research contents and conclusions are as follows:1)Through different penetration tests,the feasibility of acrylic acid polymerization modification is clarified.The hydraulic conductivity of sodiumized calcium bentonite is significantly reduced after acrylic acid polymerization modification.In the improved fluid loss test,the fluid loss is consistent with the hydraulic conductivity of the flexible wall.As the polymer content increases,the hydraulic conductivity and fluid loss both decrease.When the modified bentonite polymer content is 10%,it can meet the requirements of anti-seepage.2)Through the Batch adsorption test,the adsorption performance and adsorption mechanism of acrylic acid polymer modified bentonite and sodiumized calcium bentonite to the characteristic pollutants（Pb and Cr）of the contaminated site were clarified.Compared with sodiumized calcium bentonite,the modified bentonite has higher adsorption capacity for Pb²⁺and Cr³⁺under optimal conditions.The adsorption mechanism of acrylic acid polymerized bentonite and sodiumized calcium bentonite for Pb²⁺is ion exchange and precipitation,and the adsorption of Cr³⁺is mainly ion exchange adsorption.3)Through the dialysis leaching test,the factors affecting the diffusion of Pb²⁺in the acrylic polymer modified bentonite-based barrier material were explored.The study found that the effective diffusion coefficient of Pb²⁺decreased with the increase of modified bentonite content,and increased with the increase of pollutant concentration.