Research On The Modification Of Hematite Morphology By GMA Derivatives And Their Application In Photocatalytic Fenton Reaction

The development of the chemical industry has brought about many environmental problems,such as air,water and soil pollution.The degradation of water pollutants has become more and more difficult because of the increasingly variety and the complexity of pollutant structure.As an advanced oxidation process?AOPs?,the Fenton reaction become an effective route for water treatment through producing highly oxidic hydroxyl radicals which can degrade the organic pollutants indiscriminatively.Heterogeneous catalysts have been developed to avoid problems of low pH condition and secondary pollution caused by traditional Fenton reaction.As a semiconductor,?-Fe₂O₃ is considered to be the most promising heterogeneous Fenton catalyst because its proper band gap?².2 eV?,chemical stability;environmental safety and abundent distribution on the earth.Herein,?-Fe₂O₃nano-crystals and meso-crystals with various morphologies were prepared using small molecules,reactive monomers and their polymers with ortho-hydroxyl and hydroxy-amino structures as templating agents,and applied as Photo-Fenton catalysts.Using ferric chloride hexahydrate as iron source and ethanolamine as template,?-Fe₂O₃nanocrystals were prepared via hydrothermal method.The effect of ethanolamine concentration,temperature and iron concentration on the morphology of nanocrystal were studied.Hexagonal bipyramids with 12{012}faces exposed were obtained when the concentration of ethanolamine is 0.27 mmol/L.However,the?-Fe₂O₃ nanocrystals shows poor performance in the photo-Fenton degradation of rhodamine B with rate constant of0.0012 min^-1,probalbely due to their low specific surface area.Reactive monomers with vicinal diol and alkamine structures were obtained by hydrolysis and aminolysis of glycidyl methacrylate?GMA?.The two monomers were used as templating agents for hydrothermally preparation of mesocrystals with plate-like morphology with dominantly{001}planes exposed and hexagonal bipyramidal morphology with mainly{116}planes exposed,respectively.These meso-crystals with a size of about 1?m,showed relatively high Photo-Fenton catalytical activity for the degradation of rhodamine B,with rate constant up to 0.0122 min^-1 and 0.0094 min^-1,respectively.The higher Photo-Fenton performance may benefits from high specific surface area and unique morphology.Polymers with vicinal diol and alkamine structures were synthesized by a simple solution polymerization of the reactive monomers above,and used as templates for the prepareation of the spherical and ellipsoidal heamtite meso-crystals.These two samples were used as Photo-Fenton catalysts for Rh B degradation and showed good performance with rate constant up to 0.0148 min^-1 and 0.0096 min^-1,respectively,which was comparable with that of meso-crystals templating by reactive monomers.