GREEN SYNTHESIS OF HYBRID SUPERABSORBENT HYDROGELS OF ACRYLIC ACID, MODIFIED VINYLTRIMETHOXYSILANE (VTMS) AND BAGASSEDERIVED NANOSILICA UNDER LOW-ACID AND HIGH-ACID SORPTION CONDITIONS

This study aims to determine the impact of variations in initiators and cross-linking agents on the absorption capacity, swelling ratio, and characteristics of superabsorbent hydrogels. Superabsorbent hydrogels were synthesised using acrylic acid as the monomer, ammonium persulfate (APS) as the initiator, and Vinyl Silica Nanospheres (VSNPs) as the cross-linking agent, which are modified from Vinyltrimethoxysilane and bagasse nanosilica compounds. Modification of Vinyl Silica Nanospheres (VSNPs) from bagasse silica ash to achieve Sustainable Development Goal (SDG) 13: Climate Action. The production of superabsorbent hydrogels in this study utilised the free radical polymerisation method. Analyses in this study included water absorption analysis, swelling analysis in pH 4 and pH 9.81 solutions, as well as FTIR, XRD, and SEM analyses to determine the characteristics of superabsorbent hydrogels in the best samples. The results showed that the best sample was achieved at a variation of 0.1 grams of initiator and 0.1 grams of crosslinker, with a water absorption capacity of 74,139%. The highest swelling ratio was achieved at pH 9.81, which was 31,317%. The polymerisation results showed absorption peaks at 1,044.31 cm⁻¹ and 1,169.82 cm⁻¹, corresponding to the carboxylate functional group (C-O). SEM analysis showed that the hydrogel had a complex structure with long chains, indicating the presence of cross-links between monomers, initiators, and cross-linking agents.