Enhanced phosphate removal from water by using nanoscale zerovalent iron/rectorite nanocomposite (nZVI/REC): Mediation role of nitrate

To overcome the inherent drawbacks of nanoscale zerovalent iron (nZVI) such as easy oxidation and rapid agglomeration, rectorite (REC) was selected as a proper carrier to successfully synthesize the nZVI/REC nanocomposite, and mediation role of nitrate on phosphate removal from water by nZVI/REC was systematically explored via the subsequently batch experiments. Even though in the presence of some other competitive cations/anions and humic acid (HA), nZVI/REC exhibited remarkably performance towards phosphate under the mediation effect of nitrate, while phosphate in water can be effectively immobilized in a wide pH range of 3–10, and mono-anionic phosphate species facilitated adsorption. The adsorption capacities of phosphate were positively correlated with initial nitrate concentration in nitrate-mediated nZVI/REC-phosphate remediation system due to the fact that nitrate could accelerate nZVI surface corrosion and promote abundant iron (oxyhydr)oxides products formation, which were proven to be beneficial to remove phosphate via multiple mechanism including electrostatic interaction, adsorption and coagulation/co-precipitation. Furthermore, the generated plentiful of clean water in continuous flow fixed-bed system and brilliant behavior in different water matrix revealed that nZVI/REC was a promising nanocomposite and of great potential for phosphate-containing wastewater treatment co-existing nitrate ions in practice application.