Synthesis and characterization of gamma radiation-induced (3-acrylamidopropyl) trimethylammonium chloride-acrylic acid functional superabsorbent hydrogel

The present study is mainly focused on the gamma radiation-induced synthesis of (3-acrylamidopropyl) trimethylammonium chloride-acrylic acid (APTAC–AAc) superabsorbent hydrogel and just the investigation of the selective adsorption to the specific metal ion. The hydrogels were synthesized in an aqueous medium at a 1:1 ratio of APTAC and AAc by applying gamma radiation from a Co-60 source at different doses. It was found that the hydrogels prepared by applying 5 kGy and 10 kGy doses yield about 96.22% and 96.40% which are almost the same. The equilibrium swelling of the hydrogel of 5 kGy was found to be a maximum around neutral pH (246.14 g/gm of gel at pH = 6). Differential scanning calorimetry (DSC) was used to observe the thermal stability of the gel. Scanning electron microscopy image was taken to show the entangle network and metal adsorbed surface of the gel. The characteristic functional groups (–NH–, –COOH etc.) of APTAC and hydrogel were identified by using FTIR spectroscopy and confirmed the copolymerization between APTAC and AAc monomers. To investigate the selective adsorption performance of hydrogels, two types of multielement solutions having 27 and eight elements were used and it was found that the hydrogels show selectivity to silver ions. Therefore, it can be suggested that hydrogels can be used in metal adsorption selectively as well as in dye adsorption for superabsorbency.