Droplet photopolymerization as new strategy for the rapid preparation of hydrogel beads for malachite green removal

Green and efficient preparation of hydrogel beads remains a great challenge. In this study, the hydrogel beads (AGSP) were directly prepared within 10 s from drop-out to drop-down of the droplets in paraffin oil under green LED irradiation using sodium acrylate and acrylamide as the functional monomers, methacrylated carboxymethyl chitosan (CMCSG) as a crosslinker based on carboxymethyl chitosan and poly(ethylene glycol) as porogen. Molar ratios of monomers were modified to optimize the adsorption of hydrogel beads, and the optimal adsorption capacity for malachite green (MG) was 503.33 mg·g−1. Scanning electron microscopy (SEM), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and fourier transform infrared (FTIR) spectroscopy were used to determine the structural characteristics of the hydrogel beads. The removal of MG by AGSP was investigated and the adsorption kinetics and isotherms were calculated to understand the adsorption mechanism. Our research provides a green and efficient technique for preparing hydrogel beads for dye removal.