Synthesis of the poly(acrylic acid‐acrylic sodium) bentonite composite and its adsorption of Cd(II)

Abstract In order to improve the adsorptive properties of bentonite, a new poly(acrylic acid‐acrylic sodium) bentonite composite was prepared by copolymerization reaction. The properties of the bentonite composites were investigated. Based on the amount of acrylic monomers dissolution and Cd 2+ ions adsorption as objective functions, the optimal conditions which were determined with single‐factor experiments are as follows: the neutralization degree of acrylic acid, the polymerization temperature, the polymerization time, and the mass ratio of bentonite to acrylic acid monomer unneutralized were 20%, 80 °C, 3 h and 8 : 2, respectively. The bentonite composite was characterized by XRD, IR, and SEM. It was indicated the basic structure of bentonite had not been destroyed when the monomers were intercalated into the bentonite interlayers. The synthetic products had excellent adsorption properties to Cd 2+ ions, such as the removal rate of Cd 2+ ions reached 99.9% for 100 mL solution with initial Cd 2+ ions concentration of 50.0 mg/L by adding 0.5 g sample of the bentonite composite, whose removal rate was significantly superior to calcium bentonite and other modified bentonite reported in literatures. The adsorption process to Cd 2+ ions was corresponding with the Lagergren secondary adsorption kinetics equation and the Langmuir isotherm equation. © 2016 Curtin University of Technology and John Wiley & Sons, Ltd.