Oxidative Degradation Of 4-Chlorophenol Catalyzed By Surface Modified Nono-Fe₃O₄

The increasingly serious water pollution problems accompanying the development of the society have caused widespread concern of the whole world.In the current,among the various developed wastewater treatment technologies,advanced oxidation technologies are widely used because of their characteristics of strong oxidizing capacity and high efficiency in degrading organic pollutants.Among them,the Fenton-like processes is more favorable.Using cheap H₂O₂ and O₂ as the oxidant to degrade organic pollutants,the treatment does not cause secondary pollution because the reduction product is H₂ O.However,in order to ensure their efficiency toward the degradation of organic pollutants,it must take effective means to activate them to produce strong oxidizing free radicals.Possible catalysts are iron-based oxides.This article developed two different heterogeneous like-Fenton catalysts Fe₃O₄ and Cu0/Fe₃O₄,and used them to active H₂O₂ and O₂ to degrade 4-chlorophenol,respectively.The main contents are described as follows.?1?Fe₃O₄ magnetic nanoparticles?MNPs?were prepared through a solvothermal method with Fe?NO₃?₃·9H₂O as a precursor in the presence of ethylene glycol,which acted both as a solvent and reducing agent.The structure,shape and the specific surface area of Fe₃O₄ MNPs were characterized by XRD,Raman,TEM and BET.The results indicated that the as-prepared spherical Fe₃O₄ MNPs were in diameters of about 15 nm with a specific surface area of 91.9 m2g-1.The Fe₃O₄ MNPs were used to active H₂O₂ to degrade 4-chlorophenol.The initial concentration of pollutants,catalyst loading,H₂O₂ dosage and the solution pH were optimized in the experiment.Under the optimized conditions,0.4 mmol L-1 4-CP could be efficiently degraded within 15 min by 0.3 g L-1 Fe₃O₄ and 1.6 mmol L-1 H₂O₂ when the initial solution pH was 5.7.By FT-IR analysis,it was showed that the mechanism of Fe₃O₄ MNPs activated H₂O₂ to degrade 4-CP was attributed to the formation of abundant hydroxyl groups and strong coordination function on the surface of Fe₃O₄ MNPs.In fact,the obtained Fe₃O₄ MNPs here were able to be considered as surface modified Fe₃O₄ MNPs,and the preparation method combined the preparation step and the surface modification step into one.?2?On the basis of the above preparation system,extra Cu?NO₃?₂·3H₂O was added to act as copper source,and Cu0/Fe₃O₄ nanocomposite catalyst was prepared.Its composition and morphology were characterized by XRD,TEM and SEM.The particle sizes of Cu0/Fe₃O₄ were in the range of 50⁷0 nm.We used them to activate dissolved oxygen to degrade 4-chlorophenol.The results indicated that under the air atmosphere conditions,the removal of 4-CP reached 99.5% within 60 min by 1.0g L-1 Cu0/Fe₃O₄.By exploring the effects of different Cu/Fe molar ratio on 4-CP degradation,it was confirmed that the optimum molar ratio of nCu/n?Cu+Fe?was 0.25 in the preparation.By comparing with the degradation of single component Cu0 and Fe₃O₄,it further confirmed that there was a synergistic effect of Cu0 and Fe₃O₄ in Cu0/Fe₃O₄ nanocomposites activation of O₂.We also used Cu0/Fe₃O₄ to degrade other organic pollutants,and the universal applicability was confirmed.?3?By trapping experiments,radical fluorescent probe techniques and ESR techniques,we identified the reactive oxygen species in the Cu0/Fe₃O₄-Air system,and suggested that reactive oxygen species were formed via the activation of dissolved oxygen in the following one-electron rout?O₂ ? ·O₂? H₂O₂ ? ·OH?.By characterizing the catalyst before and after the degradation experiment by XPS,we presented its possible mechanism of activating O₂ and explained the reasons for having a wide pH application range and efficiently catalytic activity of the catalyst.