Facile fabrication of ion/pH dual responsive semi-interpenetrating network hydrogel microspheres based on sodium alginate for efficient dye removal

In recent years, the application of hydrogel microsphere adsorbent in wastewater treatment has attracted much attention. Herein, semi-interpenetrating network (semi-IPN) hydrogel microspheres based on sodium alginate (SA) were facilely fabricated by inverse suspension polymerization using diacetone acrylamide and zwitterionic sulfobetaine methacrylate as monomers, N, N′-methylenebisacrylamide as a crosslinker. Single-factor experiments were applied to optimize the fabrication conditions of hydrogel microspheres. The ion/pH dual responsiveness of the microspheres was confirmed through the swelling experiments. The swelling degree of the microspheres first decreased and then increased with the increase of pH, and increased with the increase of ion concentration. Moreover, the swelling behavior had good cycling and repeatability. Unexpectedly, its swelling degree does not change significantly with temperature variation. The adsorption experiment indicated that the maximum adsorption capacity for Eosin Y reached 330.56 ± 3.64 mg/g. The adsorption process is spontaneous and conforms to the pseudo-second-order kinetic model and Langmuir isotherm model. The microspheres have excellent stimulation response, antifouling and reusability, and are easy to prepare. They have broad application prospects in water treatment.