A facile sol-gel synthesis of chitosan-boehmite film with excellent acid resistance and adsorption performance for Pb(II)

A chitosan-boehmite (CS-boehmite) film with excellent acid resistance for effective Pb(II) removal was successfully synthesized via a facile sol-gel method. The composite, corresponding boehmite and CS films were characterized by XRD, ATR-FT-IR, TG, SEM and XPS. The static adsorption experiment showed that their adsorption well matched the pseudosecond order model on chemisorption adsorption, and the modified Langmuir model on homogenously surface for monolayer adsorption. Especially, the composite film with crosslinking mass ratio of 1:1 did not dissolve after shaking in an acidic solution of pH = 2.0 for 1 h due to formation of the monodentate C(O-Al)(2) ligand, while the boehmite and CS films dissolved 24 wt% and 100 wt%, respectively. The maximum adsorption capacity of the com posite film is 33.00 mg/g from the modified Langmuir model which is much higher than 19.57 mg/g of the boehmite film and 17.48 mg/g of the CS film, respectively, and these values are highly close to their calculated values from the pseudo-second order model and also from the experiment values. Furthermore, the composite film shows strong capability of resisting disturbance for the coexisting cations (Na+, Mg2+, K+ and Ca2+); its adsorption mechanisms involve electrostatic attraction, complexation to form Pb-OH and the chemical precipitation of Pb-3(CO3)(2)(OH)(2). (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.