Evaluation of Performance\nand Stability of a Gel-Type\nPolymer Sorbent for Recovery of Phosphate from Waste Streams

Phosphorus (P) fertilizer is an essential component of\nour food\nsystem with the majority of all mined P rock processed to make mineral\nfertilizers. Globally however P rock stocks are decliningboth\nin quality and quantitywith poor P management creating a linear\neconomic system where P is mined, globally redistributed into products\nand eventually discharged into the environment leading to eutrophication.\nTo enable establishment of a circular P economy, whereby P can be\nrecovered from waste for its industrial reuse, requires the development\nof effective P recovery technologies. Adsorption via anion exchange\nis a promising technology for P recovery from waste streams; however,\nin many cases, the regeneration of the sorbent used (to allow for\nits subsequent reuse) has not been extensively investigated. We now\ndescribe a gel-type anion exchange polymer composed of vinyl benzyl\nchloride, hydroxypropyl methacrylate, and ethylene glycol dimethacrylate\nsynthesized via suspension polymerization. The obtained material was\nmodified to introduce a quaternary ammonium functionality, characterized,\nand tested for phosphate capture, in the presence of competing anions\nand from wastewater samples. Fixed-bed experiments were conducted\nusing monobasic phosphate as adsorbate to test polymer performance,\nand its stability upon repeated adsorption/desorption cycles was investigated\nby solid-state NMR, revealing that no degradation or loss of P binding\nperformance across 50 regeneration cycles. Excellent polymer performance\nin the recovery of P from wastewater was also demonstrated.