Super Hygroscopic Sodium Alginate/Cellulose-Based Hydrogel Beads for Atmospheric Water Harvesting and Slope Soil Phytoremediation

Atmospheric Water Harvesting (AWH) is considered a promising approach aimed at addressing global water scarcity by extracting water from the air, which is particularly suitable for arid and water scarce regions. Here, we report an ultrahygroscopic polymer hydrogel bead (SC-LiCl/PNIPAM, SCLP) composed of renewable biomasses, hygroscopic salt, and temperature sensitive materials to extract water vapor from arid climates. Sodium alginate and carboxymethyl cellulose endow a 3D porous structure with enlarged polymer–air interfaces, enabling efficient water capture and vapor transport. Thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) can achieve phase transition under daylight conditions to assist the release water collected by hydrogels via hydrophobic interactions. Impressively, SCLP hydrogel beads display a maximum water uptake of up to 9.93 g/g–1 at a relative humidity of 90% and also demonstrate excellent water absorption and release properties in natural conditions. By virtue of plant cultivation experiments and 16S rRNA (16S rRNA), the introduction of SCLP hydrogel beads can effectively capture water from the atmosphere to alter the distribution of dominant populations of soil communities and enhance the activity of defensive enzymes, thereby alleviating the wide impact of drought stress on plant growth. This work provides a feasible prospect for large-scale manufacturing of hygroscopic hydrogels and the ecological restoration of barren slope areas.