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 calcium-bentonite (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 ( K CCP  = 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.