Green in-situ synthesis of SiO2@IOT stepped-pore materials based on iron ore tailings for rapid adsorption of ammonia nitrogen in water

In this study, a stepped-pore adsorbent was synthesized via a green in-situ method using low-cost iron ore tailings (IOT) as the silicon source. The formation mechanism was elucidated through comprehensive characterization of the material’s phase composition, microstructure, pore properties, and surface functional groups. The effects of roasting temperature, initial ammonia concentration, pH, and coexisting cations on adsorption efficiency were systematically investigated. Kinetic, isotherm, and thermodynamic analyses revealed a combined physisorption and chemisorption mechanism, with a maximum adsorption capacity of 28.72 mg/g. The process was determined to be spontaneous and entropy-driven. The material retained significant adsorption capacity after regeneration and in real wastewater tests. The adsorption mechanism primarily involved electrostatic attraction, hydrogen bonding, and cation exchange. The SI-6 adsorbent demonstrates high cost-effectiveness, excellent environmental compatibility, and strong adsorption performance, showing great potential for environmental remediation and sustainable resource utilization.