NOVEL TANNIN AND CASSIA FISTULA GUM CROSSLINKED HYDROGEL FOR CONTROLLED RELEASE OF THIAMETHOXAM: SYNTHESIS AND CHARACTERISATION

Abstract

Pesticide residues in soil and runoff water pose threats to both humans and the environment, necessitating innovative solutions. As controlled-release matrices, hydrogels offer a promising approach to mitigate this issue. Natural polymer-based hydrogels are widely synthesised due to their significant impact on the physicochemical and mechanical properties. Being naturally abundant, Cassia fistula (CF) and Tannin from Acacia catechu (ACT) could be potentially used to produce CFAC-g-SAH for effective controlled-release hydrogels for agrochemicals. The synthesised hydrogels were thoroughly characterised by FT-IR, 13C NMR, SEM, TGA, and XRD to observe structural, morphological, and thermal changes. CFAC-g-SAH was compared with ACT and CF hydrogels. The swelling studies of the synthesised hydrogel were measured by varying amounts of crosslinker and biopolymer, yielding the highest swelling for CFAC-g SAH of 185.94 g·g-1. The loading percentages of thiamethoxam were 58.49%, 36.39%, and 42.43% for CFAC-g-SAH, CF-g-SAH, and ACT-g-SAH, respectively. The CFAC-g-SAH hydrogel outperformed ACT-g-SAH and CF-g-SAH in highest swelling and longest release duration. A sustained release of up to 40 hours was achieved using CFAC-g-SAH hydrogel, followed by a non-Fickian release mechanism. Thus, the synthesised CFAC-g-SAH hydrogel emerges as a promising controlled-release device for agrochemicals with the potential to mitigate the environmental impact of pesticide residues.