Eco-friendly slow release of ZnSO₄ as a micronutrient from poly(acrylic acid: acrylamide) and guar gum based crosslinked biodegradable hydrogels

Two types of crosslinked hydrogels viz. first based on copolymer of acrylic acid and acrylamide and grafting of both monomers on guar gum were prepared and characterized using FTIR, SEM, and TGA for their structural, morphological, and thermal behaviors. Release mechanism of ZnSO4.H2O from both hydrogels was studied using ICP-OES in aqueous solutions of different pH and 0.9% NaCl salt solutions, which fit with Korsmeyer-Peppas and Peppas–Sahlin kinetic models. Swelling, release, and degradations were found to be improved for guar gum based hydrogels over hydrogels obtained from monomers of petroleum origin and demonstrated possible applications in slow release of a micronutrient for agriculture sectors.