Scalable hydrocell technology based on recycled polymers for atmospheric water harvesting

Abstract Freshwater scarcity demands materials and systems that enable efficient, low-cost, and environmentally responsible water generation. Here we report a hydrocell technology based on a recycled-polymer superabsorbent, poly(acrylamide-co-potassium acrylate) (PANSAP), synthesized through solvent-free alkaline hydrolysis of post-consumer polyacrylonitrile textiles. The process achieves an Environmental Factor (E-factor) of 0.056 when ammonia released during hydrolysis is recovered as ammonium phosphate, comparable to benchmark polymer-recycling efficiencies. The resulting cross-linked polymer exhibits a swelling capacity exceeding 200 g H₂O g⁻¹ and a stable atmospheric uptake of 0.43 ± 0.09 g g⁻¹ over 79 days at 69–90% relative humidity. Integrated into modular hydrocell plates, PANSAP delivers hybrid solar–electric desorption yields of 4–6 L day⁻¹ from 25 units at 0.90–1.25 kWh L⁻¹, approaching the thermodynamic minimum for water evaporation. Long-term cycling tests indicate negligible nitrogen loss (0.09 mg L⁻¹ NH₃ yr⁻¹), corresponding to an estimated service life beyond 2,500 cycles. Derived from recycled textiles, partially biodegradable, and agronomically beneficial through potassium release, PANSAP establishes a scalable, circular-materials framework for atmospheric water harvesting. The results position polymer-based hydrocells as a durable and sustainable platform for decentralized freshwater generation in arid and semi-arid regions.