High performance superabsorbent material based on biopolymers as a promising and sustainable framework for enhancing fresh water resources

Abstract

The fact that current fresh bodies of water are suffering climate changes and man-made pollution resulting in negative effects leading to water scarcity has become a serious issue in several areas worldwide. Therefore, exploring new opportunities to exploit alternative freshwater resources is urgent. Harvesting atmospheric water by superabsorbent materials (SAWH) is standing out from the solutions to exploit an alternative water source. In this study, functional eco-friendly hydrogels based on carboxymethyl cellulose derived from rice husks and chitosan from shrimp shells were synthesized. The hydrogel was also reinforced with nanosilica from rice husk to improve the physicochemical characteristics and water uptake. The hydrogel samples with nanosilica (HS0) or without nanosilica (H0) were obtained by a simple process including a dehydration process with acetone and a vacuum dry process. All hydrogels were investigated for absorption-desorption in water and in relative humidity (RH, 45 % and 90 %) media. The results indicated that the excellent swelling ratio of HS0 and H0 in water was about 921.49 % and 709.76 %, respectively. The high water uptake ratio of HS0 and H0 was approximately 43 % and 63 % at 90 % RH, and was 8.3 % and 9 % at 45 % RH, respectively. The structure and morphology of hydrogels were also characterized by FTIR, TGA, SEM, and BET analysis. The reusability results of HS0 and H0 in water and in RH media demonstrated that their water uptake remained nearly stable. The bio-based hydrogels have the potential to replace traditional synthetic sorbent polymers for sustainable SAWH, showing promising industrial applicability.