A BIFUNCTIONAL Fe3O4@ZEOLITE MAGNETIC COMPOSITE DESIGNED VIA A SYNERGISTIC DUAL-SITE MECHANISM FOR THE EFFIACIENT AND SIMULTANEOUS REMOVAL OF AMMONIA NITROGEN AND PHOSPHATE FROM RURAL DOMESTIC SEWAGE

Developing efficient materials for the simultaneous removal of nitrogen (N) and phosphorus (P) from rural domestic sewage is critical for eutrophication control. This study constructed a bifunctional Fe3O4@Zeolite magnetic composite via a hydrothermal method to achieve this goal. Characterization results confirmed the uniform loading of Fe3O4 nanoparticles onto the zeolite framework. The composite demonstrated excellent simultaneous removal performance at neutral pH (6.0–7.0), achieving 83.6 % ammonia nitrogen (NH4+-N) and 81.2 % phosphate (PO43–-P) removal. The adsorption followed pseudo-second-order kinetics with rapid equilibrium (60 min). The Langmuir isotherm model indicated maximum adsorption capacities of 23.5 mg/g for NH4+-N and 21.6 mg/g for PO43–-P. Mechanistic analysis via XPS revealed a distinct “site-specific” synergy: NH4+-N was captured via ion exchange with the zeolite lattice, while PO43–-P formed stable inner-sphere complexes (Fe-O-P) with Fe3O4 nanoparticles. The adsorption process was spontaneous (ΔG° < 0) and endothermic (ΔH° < 0). Furthermore, the composite exhibited excellent magnetic separability and reusability, retaining over 88 % of its initial efficiency after five regeneration cycles. It also effectively treated real rural sewage, validating its engineering potential as a robust, multifunctional environmental material.