Synthesis of iron-modified montmorillonite/Al2O3 composite adsorbents and their phosphorus adsorption performance study

The presence of excessive phosphate in aquatic systems can trigger eutrophication processes, causing detrimental impacts on ecological balance. This research developed an innovative phosphorus-adsorbing composite material through iron-modified montmorillonite integrated with Al ₂ O ₃ , synthesized via surface modification coupled with hydrothermal calcination (Fe/AlPMt), for aquatic phosphorus management. pH optimization experiments demonstrated Fe/AlPMt's effective phosphate removal capability across an extended acidic range (pH 3.0–6.0). The composite displayed superior phosphate selectivity compared to competing anions. Kinetic analysis revealed that the adsorption process conformed to a second-order reaction model, with particle internal diffusion identified as the dominant mechanism. Equilibrium studies indicated satisfactory alignment with both Freundlich and Tempkin isotherm models for phosphorus adsorption. Field testing in lake water achieved remarkable 99% phosphate elimination at a 0.3 g/L dosage. Adsorption mechanisms involved multiple pathways: electrostatic attraction, ligand substitution reactions, and precipitate formation on surfaces. The material maintained 95.8% adsorption efficiency after five regeneration cycles, demonstrating robust recyclability. These results position Fe/AlPMt as a viable solution for phosphorus-contaminated wastewater remediation.