Boosting peroxymonosulfate activation by a novel bifunctional core-shell nanoreactor MnFe2O4@HZO for nitrilotris-methylenephosphonic acid removal

Abstract

Advanced oxidation processes (AOPs) struggle to entirely remove phosphonates from wastewater, and the remaining phosphates easily cause secondary pollution. With MnFe2O4 as the core and hydrated zirconium oxide (HZO) as the shell, the magnetic core-shell nanoreactor MnFe2O4 @HZO with dual functions of "catalysis and adsorption" was designed to activate peroxymonosulfate (PMS) for nitrilotris-methylenephosphonic acid (NTMP) removal. Total phosphorus removal reached 96.5% within 180 min, with only 0.18 mg/L of phosphates left because of the full exploitation of active sites and adsorption sites. This is because of the strong inner-sphere complexation of shell for phosphates adsorption and the excellent electron transfer performance of the core for PMS activation. High NTMP removal under the protection of HZO shell could be obtained over wide pH (3−8) or complex water matrices. After five cycles, Mn leaching amount was only 0.4 mg/L. The study provides information on the design of core-shell catalysts in the PMS-AOP field for the comprehensive removal of contaminants.