Sodium Lignosulfonate-Based Biodegradable Superabsorbent Hydrogel: Fabrication, Characterization, and Application Potential

In this study, a novel biobased superabsorbent hydrogel was rapidly synthesized via open-system aqueous solution polymerization using sodium lignosulfonate (SL), sodium alginate (SA), and citric acid (CA) as biomass-derived raw materials. The optimal reaction conditions were obtained by orthogonal experiments. The hydrogel network was constructed through physical interactions dominated by hydrogen bonding, and the abundant hydrophilic functional groups endowed the hydrogel with outstanding water absorption capacities (313 g/g in deionized water and 69.7 g/g in 0.9 wt % NaCl solution) as well as excellent centrifugal water retention rates (97.6% in deionized water and 99.1% in 0.9 wt % NaCl solution). Swelling kinetic results revealed its rapid water absorption behavior, with swelling equilibrium achieved in 0.9 wt % NaCl solution within 4 min. A three-dimensional porous structure was observed in the SEM images of the hydrogel after water absorption and freeze-drying. The hydrogel exhibited superior pressurized water absorption capacities (39.1 g/g in deionized water and 15.7 g/g in 0.9 wt % NaCl solution), both exceeding the requirements of relevant national standards. It also displayed excellent absorption capacities for artificial urine and artificial blood, reaching 64.1 g/g and 117.8 g/g, respectively, which were superior to those of commercial products. Finally, the biodegradation rate of the hydrogel reached 71.7% after 28 days of soil burial. These results indicate that the material possesses promising application potential.