One-Step Preparation of Renewable and Self-Healing Guar Gum Hydrogels for Water Retention in Mine Soils

Natural polymer-based hydrogels are widely used as soil water-retaining agents due to their inherent biocompatibility and biodegradability. In this study, a self-repairing natural hydrogel was prepared using natural guar gum (GG) as the framework and borax (Na 2 B 4 O 7 ·10H 2 O) as the dynamic cross-linking agent through physical cross-linking. This hydrogel is biodegradable, cost-effective, and environmentally friendly. At a GG concentration of 0.5% and a Na 2 B 4 O 7 ·10H 2 O of 3.5% (relative to GG), the GGB-80 hydrogel optimal water absorption rate is 138.48 g/g. The high water retention capacity of this hydrogel is attributed to hydrogen bonding between the abundant hydroxyl groups on the guar gum molecular chains and water molecules, as well as the three-dimensional network structure formed by dynamic cross-linking with borax. Biodegradation testing revealed that the GGB-80 hydrogel achieved 90.48% degradation within 120 days. Furthermore, the hydrogel’s performance remains unaffected by its physical state. Upon contact with water, the dry powder spontaneously regenerates into a water-absorbing hydrogel, exhibiting an identical morphology to the fully hydrated gel and demonstrating exceptional self-healing capability. Compared to conventional synthetic water-retaining agents, this self-healing property confers significant advantages for storage, transportation, and the preparation of elastic hydrogel-based materials, offering a novel strategic approach for soil remediation in mining areas.