Peparation and swelling kinetics of chitosan-based superabsorbent resin by microwave radiation

Abstract

CS-g-PAM/AMPS superabsorbent resin was prepared by graft copolymerization of chitosan (CS), acrylamide (AM), and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) by microwave radiation. The structure and morphology of the superabsorbent resin were characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The mechanism of the reaction was also examined. The thermal decomposition process of resin in a nitrogen atmosphere was studied using thermogravimetric analysis. The absorption capacity of the resin in different concentrations of salt solution and the swelling kinetics of the resin were also discussed. The results showed that the resin with a uniform three-dimensional network was synthesized. When the mass fraction of CS was 10%, the resin showed the highest water absorption of 1 332 g/g. The absorption capacity of the superabsorbent resin decreased with the increasing concentrations of inorganic salt solution and metal valence state. The corresponding kinetic parameters, such as the activation energy (E), pre-exponential factor (A), and reaction order (n), were obtained according to the Kissinger and Crane methods. The values of E, A, and n were approximately 223.65 kJ/mol, 3.6×1017 s‒1, and 2.14, respectively. The swelling process of the resin satisfied the pseudo-second-order kinetic model, and the diffusion in aqueous solution conformed to the non-Fickian diffusion process.

Keywords

• supper absorbent resin
• chitosan
• microwave radiation
• radiation grafting
• kinetics