Catalysis and adsorption of Zr-doped Fe3O4 nanoparticles provide a new strategy for diazinon removal and phosphorus recovery from aqueous solution

As potential persistent and toxic organic contaminants, organophosphorus pesticides (OPPs) are frequently detected in various waters. However, few studies are available on removing OPPs in aqueous solution through heterogeneous catalytic activated peroxymonosulfate (PMS). Herein, Zr-doped Fe3O4 magnetic nanoparticles were prepared via a facile solvothermal method and employed to activate PMS for degrading diazinon. A series of characterization and performance tests revealed that Zr(0.3)Fe3O4 composite played a dual role as both adsorbent and heterogeneous catalyst for removal of diazinon. Attractively, the introduction of Zr into magnetite endowed the nanoparticles with prominent adsorption capacity for released phosphate during the oxidation reaction. Combined with electron paramagnetic resonance (EPR) spectra and quenching studies, Zr(0.3)Fe3O4 effectively catalyzed PMS to produce four kinds of reactive oxygen species (ROS), and 1O2 and ‧O2− were dominantly responsible for diazinon degradation. Furthermore, the possible degradation pathways of diazinon in Zr(0.3)Fe3O4/PMS system were discussed based on liquid chromatography mass spectrometry (LC-MS) analysis. In conclusion, the Zr(0.3)Fe3O4 nanoparticles can not only remove diazinon by catalytic oxidation but also immobilize degraded phosphorus, hence, this work offers a novel strategy for developing versatile composites.