Construction Of Sodium Sulfite Heterogeneous System And Its Application In Metoprolol Degradation In Water

Heterogeneous catalytic activation is important for potential application of new sulfate-radical-based advanced oxidation process using sulfite as source of sulfate radical.We report herein aheterogeneous system for sulfite activation by CoFe2O4/CuFe2O4 nanocatalyst for metoprolol removal.Factors that influence metoprolol removal were investigated,including pH and initial concentrations of components.The CoFe2O4/CuFe2O4 nanocatalyst was characterized by X-ray diffractometry(XRD)and transmission electron microscopy(TEM),and the catalytic stability was tested by consecutive runs.Radicals generated in the system were identified through radical quenching experiments and by electron spin resonance(ESR).The catalytic mechanism was further elucidated by X-ray photoelectron spectroscopy(XPS).The main conclusions are as follows:(1)The catalytic process was dependent on initial pH and followed the Langmubir-Hinshelwood equation.The generation of Co-OH complexes on the CoFe2O4 surface was crucial for sulfite activation.SO4·-was verified to be the main oxidative species responsible for metoprolol degradation.Other organic pollutants,such as sulfanilamide,sulfasalazine,2-nitroaniline,sulfapyridine,aniline,azo dye X-3B and 4-chloroaniline,could also be removed in this CoFe2O4-S(?)-O2 system.(2)Copper ferrite catalyst can activate sulfite in alkaline pH conditions,the CuFe2O4-S(?)-O2 heterogeneous system provides an effective way for metoprolol degradation.Alkaline pH and higher sulfite concentration can accelerate the removal of metoprolol.The stability of the copper ferrite catalyst was verified by batch tests.The Cu(II)-OH complex on the surface of CuFe2O4 plays an important role in the catalytic process,The redox process of Cu(?)-Cu(?)-Cu(?)may be the main catalytic mechanism of the system.We found that the SO4·-radicals contribute most to the catalytic system.The results suggest that the CoFe2O4/CuFe2O4-S(?)-O2 system has good application prospects in alkaline organic waste water treatment.