The Research Of Magnetic Catalyst Based On Degradation Of Organic Pollutants

Organic dyes have been produced largely and applied in some fields extensively with the development of industry.Inevitably,there are lots of dyeing effluents discharged from industries every year,which results in severe contamination and causes negative effluence on human.Under catalytic wet hydrogen peroxide oxidation process,the organics in wastewater can be oxidized and removed completely.Magnetic yolk-shell copper silicate has the properties of magnesim and yolk-shell structure,synthesized by a simple sacrifice template method.It has been applied in many fields,but never in the field of wastewater degradation.First,changing the types of additive such as trisodium citrate and CTAB,solvothermal temperature,the doses of copper nitrate and ammonia,magnetic and yolk-shell structured copper silicate materials were prepared by solvothermal treatment.The characterizations including TEM,SEM,EDS,XRD,FT-IR,XPS and so on were carried out.Then the materials were selected to catalytically degrade the methylene blue?MB?solution for studying the effects of the above factors on their catalytic activities as well as their morphologies.In addition,comparative experiments were done between this work and other repots to investigate the ability of this material to remove MB.Results showed that magnetic structured copper silicate?FtCS?using trisodium citrate had better dispersion and more obvious yolk-shell structure than the one?FcCS?using CTAB as stabilizer.At the same time,FtCS had better performance in removing MB.FtCS has relatively high specific surface area of 399 m²/g and high pore volume of 0.61 cm³/g,respectively,compared to the reported yolk-shell Fe₃O₄@CuSilicate with specific surface area of 135 m²/g and pore volume of 0.22 cm³/g.Besides,FtCS had the best state in both morphology and catalytic active when the synthesized temperature was 120°C and the doses of copper nitrate and ammonia all were 4 mL.Satisfyingly,FtCS was superior to others reported recent years in the treatment of MB wastewater,which proves FtCS can be a prosmsing candidate in this field.Second,during degrading MB with FtCS as catalyst prepared at optimum condition,some factors such as reaction temperature,the dosages of hydrogen peroxide and FtCS,initial pH and concentration of MB solution were adjusted in order to find how they influence the catalytic ability of FtCS.Additionally,its cycle performance was surveyed by resuing it for 4times.Furthermore,using Fe₃O₄,Fe₃O₄@SiO₂,silicate acid,copper chloride and FtCS as catalyst,separately,to find what the main active component was.At last,for knowing the degradation mechanism,we added certain amount of radical elimination agent,ter-butanol,into the reaction systems.The results demonstrated the removal efficiency of MB has reached 100%within 30 min for 100 mL MB solution?100 mg/L?with 70°C,4 mL/L of hydrogen peroxide and 0.4 g/L catalyst.The small change of conversion efficiency of MB and COD when the catalyst was used for 4 times,coupling with the little Cu²⁺dissolution of 6 ppm,certified FtCS was stable.By comparison tests and the MB conversion reduced after ter-butanol added,we found it was the copper component?Cu?II?in heterogeneous FtCS that provided active sites promoting H₂O₂ to produce hydroxyl radicles?HO·?,which made MB decomposed.The involved degradation reaction followed a pseudo-first-order kinetics.