Chlorpyrifos and diazinon elimination through pAAm-g-XG/HKUST-1@Fe₃O₄ biopolymer nanoadsorbent hydrogel from wastewater: Preparation, characterization, kinetics and isotherm

In this study, a MOF-functionalized biopolymer nanoadsorbent hydrogel was developed to effectively eliminate chlorpyrifos (CPF) and diazinon (DZ) from aquatic areas. The adsorbent system was prepared through a multi-step process, such as graft copolymer preparation of xanthan gum (XG) with acrylamide (Aam) and cross-linking with N,N'-Methylenebisacrylamide (MBA) to obtain (pAAm-g-XG), synthesis of Fe3O4 MNPs through ex-situ coprecipitation method, and covalent attachment onto the pAAm-g-XG. Finally, in-situ HKUST-1 was attached to pAAm-g-XG@Fe3O4 to obtain the pAAm-g-XG/HKUST-1@Fe3O4 biopolymer nanocomposite hydrogel. They are characterized by a variety of characteristic methods for example, FTIR, VSM, SEM, TGA, EDX, XRD, and BET confirmed the adequate preparation of pAAm-g-XG/HKUST-1@Fe3O4 biopolymer nanocomposite hydrogel. CPF and DZ, both organophosphorus pesticides (OPPs), were studied for their removal from aqueous solutions using the developed adsorbent system. The most efficient adsorption conditions were achieved by doing batch adsorption tests with varying values of solution pH, adsorbent dose, contact duration, and beginning concentrations of CPF and DZ. Additionally, model fitting was excellent for the Freundlich isotherm model, and by using the pAAm-g-XG/HKUST-1@Fe3O4 biopolymer nanocomposite hydrogel, the maximal adsorption capacity of DZ and CPF was achieved about 4525.102 and 1708.735 mg.g(-1), consequently. The pseudo-second-order (PSO) model, according to the findings, is an excellent fit for the experimental data in this research on adsorption kinetics. The hypothesized process suggests that intermolecularly by hydrogen bonding, diffusion, and entrapment in the polymeric lattice of biopolymer nanocomposite hydrogel all contribute to the adsorption of CPF and DZ onto the biopolymer nanocomposite hydrogel. The two OPPs under study responded best to regeneration studies lasting up to four cycles.