Construction of cellulose-based hydrogel compounded with modified kaolin and its removal performance for heavy metal ions and dyes in water.

In this study, modified kaolin was prepared from cheap kaolin by sulfuric acid. Through the use of potassium persulfate as an initiator and N, N'-methylene bisacrylamide as a cross-linker, SA/CMC/SKL hydrogel was effectively created by sodium alginate (SA), sodium carboxymethyl cellulose (CMC) and sulfuric acid modified kaolin (SKL) through radical polymerization. FTIR, SEM, TGA, and XPS were used to analyze the structure and characteristics of the adsorbents, and orthogonal experimentation was used to find the ideal proportion of raw materials for synthesizing hydrogel. According to the results of adsorption kinetics and isotherm studies, the adsorption process is more consistent with Langmuir isotherm and pseudo-second-order kinetic model, which can best describe the simultaneous physical and chemical adsorption processes. The maximal adsorption capacities of Pb2+, Cu2+ and MB were 879.84, 543.50 and 805.16 mg g-1, respectively, according to the Langmuir isotherm model. Ion exchange and electrostatic attraction are the mechanisms of contaminant removal, as confirmed by XPS analysis. Furthermore, even after five adsorption-desorption cycles, the resultant adsorbent maintained its great stability and good adsorption performance. To sum up, our work presents a low-cost, environmentally friendly, and extremely effective hydrogel adsorbent that effectively removes dyes and heavy metal ions from aqueous solutions.