Preparation Of Coated Ferrite Composites Using Microwave Hydrothermal Method And Microwave Catalytic Degradation Of Organic Dye

In recent years,the application of microwave catalytic degradation technology in the treatment of water pollution has attracted widespread attention.Microwave catalytic oxidation with ferrate as catalyst has become an effective method for the treatment of organic wastewater.However,in the technology of microwave catalytic oxidation of ferrate,there are many problems such as high cost of catalyst,easy agglomeration of ferrate and uneven dispersion of catalyst"hot spot".In order to solve the problem and reduce the cost,ferrate surface area increases with ferrate loading on the carrier,and the"hot spot"produced on ferrate surface under microwave irradiation can be dispersed uniformly.In this study,ferrate was modified.Using magnesium silicate and sepiolite as carriers,organic pollutants in water were degraded under microwave irradiation with ferrate supported catalyst.In the first chapter,microwave hydrothermal method was introduced to prepare Ni-MnFe₂O₄@MgSiO₃ catalyst,and applied in MW-induced catalytic degradation?Ni-MnFe₂O₄@MgSiO₃/MW?of basic fuchsin in water.The catalytic activity of ferrite composite was compared.Moreover,the effects of mass ratios of Ni-MnFe₂O₄and MgSiO₃,Initial concentration of dyes,MW irradiation time,catalyst dosage and catalyst reuse cycles on the degradation were evaluated.The mechanism on Ni-MnFe₂O₄@MgSiO₃/MW degradation was provided.The results reveal that basic fuchsin?BF?in aqueous solution can be completely degraded using 1.0 g/L Ni-MnFe₂O₄@MgSiO₃ catalyst within 3.0 min MW?700 W?irradiation.Ni-MnFe₂O₄@MgSiO₃ shows higher catalytic activity than Ni-MnFe₂O₄.The performance of Ni-MnFe₂O₄@MgSiO₃ can be maintained for three reuse cycles.The activespeciessuchas·OH,·O₂^-andh⁺playmainrolesin Ni-MnFe₂O₄@MgSiO₃/MWdegradation.Hence,Ni-MnFe₂O₄@MgSiO₃/MW technology with rapid and cost-effective degradation,magnetical separation,and no secondary pollution,demonstrates to be an effective means in removing organic pollutants in water and wastewater.In the second chapter,ferrite@sepiolite(MnFe₂O₄@sepiolite,Mn_0.5Ni_0.5Fe₂O₄@sepiolite,NiFe₂O₄@sepiolite)nanoparticles were developed using microwave?MW?hydrothermal method,and applied in MW-induced catalytic degradation?ferrite@sepiolite/MW?of organic dyes in water.The catalytic activities of three ferrite@sepiolite composites were compared.Moreover,the effects of mass ratios of sepiolite and ferrite,MW irradiation time,catalyst dosage and catalyst reuse cycles on the degradation were evaluated.The mechanism on ferrite@sepiolite/MW degradation was provided.The results reveal that rhodamine B?Rh B?in aqueous solution can be completely degraded using 4.8 g/L MnFe₂O₄@sepiolite catalyst within 3.0 min MW?700 W?irradiation.MnFe₂O₄@sepiolite shows higher catalytic activity than Mn_0.5Ni_0.5Fe₂O₄@sepiolite and NiFe₂O₄@sepiolite.The performance of ferrite@sepiolite can be maintained for three reuse cycles.The active species such as·OH,·O₂^-,and h⁺play main roles in ferrite@sepiolite/MW degradation.Hence,MnFe₂O₄@sepiolite/MW technology with rapid and cost-effective degradation,magnetical separation,and no secondary pollution,demonstrates to be an effective means in removing organic pollutants in water and wastewater.