Ca-bentonite/polymer nanocomposite geosynthetic clay liners for effective containment of hazardous landfill leachate

Geosynthetic clay liners (GCLs) consisting of bentonites are used worldwide for the containment of hazardous landfill leachates. However, the swelling of bentonite in aggressive leachates is suppressed, which critically decreases GCLs' barrier performance. This study proposed a polymerization method to prepare calciumbentonite (CaB)/polymer nanocomposites for high performance GCLs under aggressive conditions. The CaB was successfully intercalated and grafted by salt resistant poly (acrylic acid-2-acryl amido-2-methyl propane sulfonic acid-N, N'-methylene bis(acrylamide)) (abbreviated as P(AA-AMPS-MBA)) networks, leading to layered structures in the resulting nanocomposites. The swell index of P(AA-AMPS-MBA)@CaB in coal combustion product (CCP) leachate (I = 178 mM) was increased by 2.1 times relative to that of pristine CaB. Consequently, the P(AA-AMPS-MBA)@CaB exhibited excellent barrier property, with hydraulic conductivity to CCP leachate (KCCP = 6?10(-12) m/s) being four and one orders of magnitude lower than that of pristine CaB and the US standard for GCLs, respectively. In addition, polymer elution of P(AA-AMPS-MBA)@CaB is only 0.15% that of the control sample prepared by traditional physical mixing method.