Study On Preparation And Preliminary Application Of Nanometer ?-Fe₂O₃

In this paper,?-Fe₂O₃ nanoparticles were prepared by oxidation precipitation method and one-step precipitation method with iron salts.?-Fe₂O₃ were synthesized using ferrous sulfate,hydrogen peroxide and sodium dodecyl sulfate?SDS?by a simple route,the impact of varying the reaction conditions on ferrous ion convert ratio was examined,and the best reaction conditions were found.The optimal conditions of preparing?-Fe₂O₃ using ferric nitrate were investigated by adjusting SDS,precipitation temperature,pH,calcination temperature and time.Based on the one-step precipitation method,in order to explore the impact of different kinds of iron salts on the product,?-Fe₂O₃ were synthesized with ferric chloride.The prepared materials were analyzed with a series of characterization methods?TG,FTIR,XRD,SEM?,and the differences of the products obtained under different preparation methods were compared,the best preparation process was selected by comparing the results.The results are as follows:With the oxidation precipitation method,as for 40m L ferrous ion solution,which contains0.9mol ferrous ion per liter,the best conditions are as follows:15m L hydrogen peroxide;15min reaction time.Under the reaction conditions above,the convert ratio is 99.1%,and the size of the prepared nanoparticles is 30-50nm.?-Fe₂O₃ were synthesized using ferric nitrate as ferric salt and ammonium hydroxide as precipitant by direct precipitation method,optimal conditions are as follows:0.03g SDS;65?;pH=8;calcination temperature and time:500?,2h.The uniform particle size of obtained?-Fe₂O₃ is about 50nm.Spherical?-Fe₂O₃ with a diameter of50nm were synthesized using ferric chloride with a one-step precipitation method.Oxidation precipitation method has complex process and long cycle,and the obtained?-Fe₂O₃ particles were severely agglomerated;While one-step precipitation method has simple operation,and the obtained particles have high crystallinity,uniform size and good dispersity.Therefore,one-step precipitation method is preferable to oxidation precipitation method.On the basis of one-step precipitation method,the morphology of?-Fe₂O₃ particles synthesized with different kinds of iron salts were diverse,the particles synthesized with ferric chloride have uniform particle size and good dispersity,which makes it easy to be used as photocatalyst,and the particles prepared with ferric nitrate and ferric chloride have similar crystallinity,which makes it better to select ferric chloride.Based on the analysis above,it is the best solution to prepare?-Fe₂O₃ nanoparticles using ferric chloride as iron salt by a one-step precipitation method.The prepared?-Fe₂O₃ was used in basic research experiment of photocatalytic degradation of dye wastewater,the results are as follows:the prepared?-Fe₂O₃ as photocatalyst,the catalytic efficiency is the best when the dosage is 0.2g/L.At a substrate concentration of 20mg/L,after75 minute of catalytic reaction,the degradation rate can reach 42%,under the same condition,the efficiency of commercial?-Fe₂O₃ is lower than 20%.