Preparation, characterization and swelling studies of bio-waste-derived absorbent hydrogels

A class of polymeric materials known as “hydrogel products” have a hydrophobic structure that enables them to hold significant volumes of water in their three-dimensional networks. It is thought that it is of utmost importance that they can be used extensively in a variety of industrial, biomedical and environmental applications. In this view, I have synthesized a uniuqe hydrogel made from cellulose extracted from banana pseudostem (BPC). This hydrogel exhibits superabsorbent properties. The synthesis was achieved by free-radical graft copolymerization of poly 2-(acryloyloxy) ethyl trimethylammonium chloride copolymer N,N-dimethylacrylamide (AETAC- co-DMA) onto a BPC backbone using ammonium persulfate as the initiator and methylene bisacrylamide as the cross-linking agent. The graft copolymer was studied using FT-IR spectroscopy to confirm its structure. It was further characterized by field-emission scanning electron microscopy (FESEM) and thermogravimetric analysis (TGA) to determine its morphological and thermal properties, respectively. The Effect of various parameters of free-radical graft copolymerization on the swelling behavior of the hydrogel was studied and the optimized copolymer was used to conduct pH and salt sensitivity tests on the hydrogel. The maximum water uptake of the hydrogel was found to be 427  g/g under optimum conditions of initiator, monomer and cross-linker concentrations of 0.0657 mol/L, 1.6 mol and 0.0972 mol/L correspondingly. The hydrogel was found to be pH and salt-sensitive and the salt uptake followed the order KCl>NaCl>CaCl>FeCl3. The excellent water absorbency, pH and salt responsiveness of the prepared hydrogel suggest its applicability not only in agriculture and wastewater treatment, but also in biomedicine for the controlled release of drugs.