Recovery of phosphorus from aqueous solution by magnetic TiO2*/Fe3O4 composites

Highlights: • TiO₂*-based composites have barely been studied for phosphate-recovery from water. • The preparation process of TiO₂*/Fe₃O₄ is easier than other TiO₂ supported composites. • The phosphate-adsorption mechanisms are electrostatic attraction and ligand exchange. • It is possible for TiO₂*-based composites to integrate photocatalysis with adsorption. Considering the phosphorus pollution in the water and the shortage of phosphate rock resources, the TiO₂*/Fe₃O₄ composite is prepared by sol–gel method to adsorb and recover phosphate from wastewater. The physio-chemical properties combined with adsorption experiment results show that the phosphate adsorption of TiO₂*/Fe₃O₄ is mono-layer chemical adsorption with electrostatic attraction and ligand exchange. The adsorption capacity reaches 64.6 mg/g at 25 °C in pH 6 and the phosphate recovery rate is over 85% after 5 recycling times. The TiO₂*/Fe₃O₄, which is easily separated magnetically from water with excellent phosphate removal performance of municipal sewage, is a promising specific phosphate adsorbent.