Citric acid - crosslinked cellulose derivatives superabsorbent hydrogels (SAH) as sustainable alternatives for personal hygiene applications
Muhammad Shahidul Islam, Dylan Sproule, Jessica Yohans, Pansit Chenananporn, Evelyn K. F. Yim, Arvind Gupta, Tizazu H. Mekonnen
Abstract
This study explores the development of citric acid (CA)-crosslinked superabsorbent hydrogels (SAHs) based on cellulose derivatives as sustainable alternatives to conventional petroleum-based superabsorbent polymers (SAPs) used in personal hygiene products. A biodegradable and biocompatible hydrogel formulation was synthesized using CA as a green crosslinking agent, with sodium carboxymethyl cellulose (Na-CMC) as the primary polymer and hydroxyethyl cellulose (HEC) as the secondary polymer, in varying ratios. The effects of polymer composition, swelling medium, pH, and water/saline solution absorption under load (AUL) were systematically evaluated by employing thermal analysis, rheology, water absorption capacity, swelling/deswelling kinetics, and soil biodegradation tests. Biocompatibility was also assessed via indirect contact cytotoxicity assays using mouse fibroblast cells. The optimized formulation, particularly the CMC—1.5 % CA hydrogel, exhibited high equilibrium water absorption (Q eq ) of 110 g/g in saline media at 38 °C, favorable swelling/deswelling behavior, rheological robustness, significant biodegradability (72 % within 7 weeks under composting conditions), and non-cytotoxicity (>80 % cell viability). These results highlight the potential of these hydrogels as biodegradable, biocompatible materials aligned with the Sustainable Development Goals (SDGs), especially for eco-friendly hygiene applications. • Citric acid–crosslinked cellulose hydrogels showed superior water absorption, exceeding commercial superabsorbents. • Hydrogels were up to 72 % biodegradable and non-cytotoxic, meeting key safety requirements. • Green-crosslinked cellulose hydrogels offer an eco-friendly alternative to synthetic absorbent materials. • The hydrogel process is simple, high-yield (>85 %), and scalable for industrial hygiene applications.