(385at) Low-Cost Hydrogel for Sustainable Phosphate Recovery and Ion Separation

Research Interests: polymeric materials, ion separation, environment pollution

Phosphate is both a critical agricultural fertilizer and a major pollutant in eutrophication. The soaring price of P fertilizers poses significant risks to global food security. Recycling phosphate from phosphate-rich water sources presents a sustainable solution to address environmental and economic challenges. However, conventional phosphate sorbents often require concentrated salt, acid, and base, sometimes even elevated temperatures for desorption. This novel hydrogel was synthesized from commercially available materials, polyethyleneimine (PEI) and poly (methyl vinyl ether-co-maleic anhydride) (PMVEMA). By adjusting the hydrogel’s amino and carboxyl groups by pH, the hydrogel can capture phosphate and release phosphate efficiently at low NaOH concentrations (<1 mM), the lowest base concentration for complete P recovery. This hydrogel represents a significant advancement in sustainable phosphate recovery, combining cost-effectiveness, high adsorption capacity (~100 mg/g), and ease of reuse. In the fixed-bed column study, the hydrogel showed excellent regeneration ability over three cycles while maintaining high capacity. The anion affinity to the PEI/PMVEMA hydrogel followed the order: SO₄^2- > H₂PO₄^- > NO₃^- at pH 4.5. Selective desorption of sulfate and phosphate from hydrogel was achieved by lowering the desorption pH, demonstrating its potential as an ion-exchange material for targeted anion separation and recovery.