The Synthesis Of Glutathione Modified Fe₃O₄ Nanoparticles And The Efficiency And Mechanism In H₂O₂ Catalyzation For 2,4-dichlorophenol Degradation

Phenols are one kind of essential industrial raw materials and have been widely used in various industries like pharmaceutical production,printing and dyeing industry.,paper manufacture,and leather processing.And phenols are also a kind of pollutant feathered as high toxicity and refractory,which has posed a threat to the environment.In recent years,Fenton-like reaction are frequently applied to treat phenol pollution,due to its high efficiency,strong oxidation and simple to operate.But most catalysts do not perform well under neutral solution p H and cannot degradate pollutants effectively.Hence,this study plan to develop a new catalyst,which can effective catalyze hydrogen peroxide under neutral solution pH.Nanoscaled Fe₃O₄ has been increasingly used as catalyst for advanced oxidation processes,because of advantages,suc h as special structure,magnetism,eco-friendly,cheap,easily prepared and modification.But nanoscaled Fe₃O₄ has a low catalytic property under neutral solution p H as well.Glutathione is a tripeptide that possesses several kinds of functional groups,such as carboxyl,amine,and thiol groups,and it can be combine with metallic compound.So this paper proposes using glutathione to modify nanoscaled Fe₃O₄.Nanoscaled Fe₃O₄ was prepared through co-precipitation method.After that,glutathione modified Fe₃O₄ nanocomposite（Fe₃O₄@GSH）was fabricated using oxidative polymerization method.Characterization methods like X-ray diffraction（XRD）,transmission electron microscopy（TEM）,Brunauer-Emmett-Teller（BET）,and Fourier transform infrared（FTIR）were applied to compare the physical and chemical changes of nanocomposites before and after modification.And the results showed that the co-precipitation method prepared nanocomposite was pure Fe₃O₄,and the glutathione was steadily combined with Fe₃O₄.In addition,both the synthesized materials were nanoscaled.Besides,the modified Fe₃O₄ possess better dispersity and larger specific surface area than Fe₃O₄ nanocomposite,and abundant functional groups,such as carboxyl,amine,and thiol groups.2,4-dichlorophenol was chosen as the model pollutant of phenols for the Fe₃O₄@GSH/H₂O₂ reaction system.a series experiments were implemented to compare the catalytic performance Fe₃O₄ before and after modification.Factors（H₂O₂dosage,catalyst loading,initial solution p H,and 2,4-DCP concentration）influence2,4-DCP degradation,catalyst reusability and 2,4-DCP mineralization were also studied.The results showed that the optimum dosage of oxidant and catalyst were 5mM and 2 g/L respectively,and the final 2,4-DCP（100 mg/L）removal and dechlorinate efficiency reached 99%and 70%respectively in the Fe₃O₄@GSH/H₂O₂system.However,almost no 2,4-DCP was degraded in the system of Fe₃O₄/H₂O₂under the same reaction conditions.In addition,the 2,4-DCP degradation efficiency still reached 94%after three recycling times,which indicate the excellent catalytic character and stability of the Fe₃O₄@GSH.The results of quenching tests and electron paramagnetic resonance（EPR）experiments suggested that the hydroxyl radicals（·OH）was the main reactive oxidizing species responsible for pollutant degradation in the Fe₃O₄@GSH/H₂O₂reaction system,and the trend of 2,4-DCP degradation match well with the signal intensity changing.A series of comparative e xperiments were carried out to explore the reaction mechanisms and the role of glutathione between the two systems of Fe₃O₄@GSH/H₂O₂ Fe₃O₄/H₂O₂,such as iron leaching,2,4-DCP removal efficiency,H₂O₂ decompose rate and the intensity of EPR signal at p H 3.0.According to the experimental results and previous researches,the possible role of GSH in the system may involve the enhancement of iron leaching at neutral solution pH and the collective action of carboxyl and amine groups for H₂O₂,all of these are in favour of the oxidizability enhancement of the system.