Functional Hydrogels for Selective Phosphate Removal from Water and Release on Demand

Area of Science:

• Environmental chemistry
• Materials science
• Sustainable agriculture

Background:

• Phosphate fertilizer overuse causes economic and environmental issues, impacting health, water, and food security.
• Effective phosphorus (P) management is critical for sustainable resource cycling.
• Developing efficient methods for phosphate capture and release is essential.

Purpose of the Study:

• To develop and characterize a novel hydrogel system for selective inorganic phosphate capture and release.
• To investigate the synergistic effects of polyethylenimine (PEI) and poly(methyl vinyl ether-co-maleic anhydride) (PMVEMA) in the hydrogel.
• To evaluate the hydrogel's performance across various pH conditions and phosphate loadings, assessing selectivity against nitrate.

Main Methods:

• Synthesis and characterization of a PEI/PMVEMA hydrogel system.
• Phosphate adsorption experiments under varying pH and loading conditions.
• Phosphate desorption studies and selectivity assessment in the presence of nitrate.

Main Results:

• The PEI-enriched hydrogel demonstrated high phosphate (P) capturing capacity (up to 65 mg P/g) between pH 2.0 and 7.0.
• Efficient phosphate release (96%) was achieved under mild alkaline conditions (<0.001 M NaOH), a record low concentration.
• A high separation factor (α ≈ 50) was observed for phosphate over nitrate at specific eluent pH levels.

Conclusions:

• The novel PEI/PMVEMA hydrogel system offers an efficient and selective method for inorganic phosphate capture and release.
• The system's ability to function under mild desorption conditions and its high selectivity present a promising solution for phosphorus management.
• This technology contributes to mitigating the adverse impacts of phosphate fertilizer overuse and enhances resource sustainability.