Fe3O4-modified zirconium-based metal-organic framework as a recyclable sorbent for rapid and efficient phosphate removal

A magnetic Zr-MOF@Fe 3 O 4 material for rapid phosphorus removal was developed. • A maximum phosphate uptake of 141.0 mg P g −1 was achieved. • Phosphate adsorption mainly involved ion exchange and inner-sphere coordination. • DFT calculation elucidated the orbital hybridization between Zr and O atoms. Environmental remediation of phosphorus-containing wastewater is crucial for ecological protection and sustainable resource development. However, existing adsorbents generally suffer from slow phosphate uptake kinetics, limited adsorption capacity and difficult solid-liquid separation. Here, a magnetic Fe 3 O 4 -modified zirconium-based metal–organic framework (Zr–MOF@Fe 3 O 4 ) was synthesized via a simplified hydrothermal process for highly selective phosphate adsorption. Outperforming most reported adsorbents, Zr–MOF@Fe 3 O 4 –1.0 with the porous framework and abundant active sites significantly enhanced phosphate adsorption kinetics, achieving an adsorption rate of 173.3 mg P g –1 h −1 within 0.5 h and a maximum adsorption capacity of 141.0 mg g −1 . Experimental results and density functional theory calculations indicated that the efficient phosphate capture was primarily attributed to synergistic effects of electrostatic adsorption, ion exchange with surface hydroxyl groups, and inner-sphere complexation via Zr–O–P bonds. Excellent anti-anion interference performance, coupled with robust cycling stability and rapid magnetic separation, collectively highlight the application potential of Zr–MOF@Fe 3 O 4 for phosphate removal from complex wastewaters. Download: Download high-res image (225KB) Download: Download full-size image