Recyclable and eco-friendly xanthan gum-based hygroscopic hydrogel for atmospheric water harvesting.

Water scarcity is a pressing issue in several regions of the world. Nevertheless, atmospheric water vapor offers an abundant freshwater source that is constantly renewed through the hydrological cycle. Among water harvesting technologies, Sorption-based methods, which involve sorbents to capture water vapor and heat to release the sorbed water, have proven its effectiveness for collecting moisture. This study introduced a novel type of sorbent hydrogel made from natural, cost-effective, and non-toxic polysaccharide polymer. The hydrogel was prepared by grafting partially neutralized acrylic acid (AA) monomers onto Xanthan Gum (XG) using N, N′-methylene-bis-acrylamide (N-MBA) as a crosslinker and potassium persulfate as an initiator. Characterization was done using FTIR, SEM, TGA, and XRD. It was found that the swelled sample showed a higher value of water uptake which reached to about 50% of their maximum swelling capacity at the first 3 min. Moreover, the water uptake of the hydrogel increased as the amount of AA and CaCl2 increased up to a certain value and decreased beyond this value. While, increasing the concentration of N-MBA led to decreasing the water uptake. Finally, over 94% of the sorbed water being rapidly released. While, the hydrogel showed excellent reusability without noticeable fading.