Degradation Of Organic Dyes With Fenton-like Reaction System By Magnetic Transition Metal Oxide Catalysts

In recent years, because large amount of industry waste water discharged into the environment as well as the fresh water resource become scarce, more and more researchers involved in the field of waste water purification and water recycle. Among these researches, advanced oxidation processes methods（AOPs） based on the Fenton-like reactions have been attracted more and more attention for its excellent effect in degrading pollutants in wastewater.This research is aimed on degrading organic dyes in simulated waste water with Fenton-like reaction system, which include catalysts of active metal oxide. We synthesized 2 kinds of catalysts, which are Ni Fe₂O₄ nanoparticles and S-modified CoFe₂O₄（S-CoFe₂O₄） nanoparticles through Sol-Gel and co-precipitation methods respectively. A series of catalytic reactions have been conducted to degrade Malachite green（MG） for NiFe₂O₄ and Acid Orange（AOII） for S-modified CoFe₂O₄. Many influential factors of catalytic efficacy are researched such as calcinating temperature,initial pH value, the addition amount of constituents of reaction system. Moreover, the durability of catalysts and reaction mechanisms are also investigated.The following conclusions were acquired:（1） The catalyst of NiFe₂O₄ obtained by Sol-Gel method was characterized by XRD and BET, which proved its nanoparticle form. The concentration of Malachite green（MG） in simulated waste water was 25 mg/L. Under the optimum reaction conditions of 1.0 g·L-1 NiFe₂O₄ dosage, 20 m M H₂O₂, initial pH=7.0, above 99% of decolorization rate was achieved in 40 min, 298 K.（2） The catalyst of S-modified CoFe₂O₄ synthesized by co-precipitation method was characterized by XRD, BET, FT-IR, SEM and VSM, which proved its well form of magnetic nanoparticle as well as sulfur presence in it.（3） The concentration of Acid Orange（AOII） in simulated waste water was 50mg/L. Under the optimum reaction conditions of 1.0 g·L-1 S-CoFe₂O₄ dosage, 3 mM H₂O₂, initial pH=6.0, 298 K, above 98% of decolorization rate was achieved in 30 min with 40% of total organic carbon（TOC） removal. For durability discussion with used catalyst, BET, XRD and EDS were also measured to further discuss reasons ofdecrease in catalytic activity.