Selective removal of phosphate by magnetic NaCe(CO3)2/Fe3O4 nanocomposites: Performance and mechanism

Abstract

Phosphorus (P) contamination has become a worldwideissuedue to its adverse impacts on water security and human health. Additional research is required because the selectivity and adsorption capacity of P adsorbents continue to impede their practical application. Herein, a novel NaCe(CO3)2/Fe3O4 nanocomposite (NCF) with good magnetic properties were synthesized through a modified hydrothermal method for P removal from water. With an adsorption capacity of 86.69 mg P g−1, the NCF demonstrates outstanding phosphate uptake efficiency. At low P concentrations, the removal rate exceeded 90.0%, and the residual P concentration was below 0.1 mg P L−1. Notably, NCF demonstrated exceptional P selectivity in actual water containing multiple substances, with negligible interference from competing ions and humic acid (HA). The adsorption processes of NCF were well described by the pseudo-second-order kinetic model (PSO) and Langmuir isotherm model, corresponding to its kinetics and thermodynamics, respectively. The exhausted NCF can be regenerated and retain an effective phosphorus removal capability even after regeneration. Characterization results demonstrated that electrostatic attraction and ligand exchange were responsible for P adsorption, forming stable CePO4 crystals with low solubility. Moreover, the NCF demonstrated some efficacy in removing typical organic and inorganic phosphorus.