A Sustainable Approach: Cellulose-Based Biodegradable Water-Retaining Agents Facilitating Mine Restoration in Arid Xinjiang Mining Zones

To address the poor biodegradability and high environmental risks of traditional synthetic water-retaining agents (WRAs), and the vegetation colonization challenge induced by organic matter deficiency in saline-alkali mining areas, a biodegradable WRA (CCM−CMC) was facilely synthesized from natural cellulose (CCM) and carboxymethyl cellulose (CMC) with epichlorohydrin (ECH) as a crosslinking agent. An in situ non-topsoil replacement remediation system of “superabsorbent polymer–biological fertilizer–native stress-tolerant plants” was established, and its water absorption-retention performance, biosafety, and ecological remediation efficacy were systematically evaluated. CCM−CMC displayed excellent equilibrium swelling ratios (1218, 443, 305, 148 g/g in distilled water, tap water, mining reclaimed water, and 0.9 wt% NaCl solution, respectively), with a 57.28% weight loss after 30-day soil burial, verifying favorable biodegradability. Soil application of CCM−CMC improved soil water-holding capacity by up to 39.20%, and maximally increased pakchoi germination rate, plant height, and dry weight by 23.33%, 327.4%, and 430.8% under drought stress. Field trials in Xinjiang arid mining areas achieved an over 80% survival rate for over ten native stress-tolerant plants, and significantly ameliorated the soil physicochemical properties. These eco-friendly WRAs and derived remediation technology avoid the high costs and ecological disturbance of topsoil replacement, providing a practical technical strategy for the ecological restoration of arid and highly saline-alkali mining areas.