A new salt-resistant superabsorbent hydrogel based on kappa-carrageenan

In this work, a novel biopolymer-based superabsorbent hydrogel was synthesized through crosslinking graft copolymerization of 2-hydroxyethyl acrylate (HEA) onto kappa-carrageenan, using potassium persulfate (KPS) as a free radical initiator in the presence of methylene bisacrylamide (MBA) as a crosslinker. The chemical structure of the hydrogels was confirmed by FTIR spectroscopy. The morphology of the samples was examined by scanning electron microscopy (SEM). The certain variables of the graft copolymerization (i.e. the monomer, the initiator, the polysaccharide, and the crosslinker concentration) were systematically optimized to achieve a hydrogel with maximum swelling capacity. The swelling ratio in various salt solutions was also investigated in detail. Since this hydrogel exhibited a very high absorptivity in saline, it may be referred to as low salt sensitive superabsorbent. The swelling of superabsorbing hydrogels was also measured in solutions with pH ranging from 1 to 13.