Studies Of Preparation Of ZnO Under Microwave Irradiation And Their Properties For Photocatalytic Degradation Of CTAB

With the wide application of surfactants in industry,plenty of surfactant-containing waste water has been produced,causing serious pollution of the environment.Quaternary ammonium salt cationic surfactant is a kind of toxic surfactants,which is not easy to degrade and inhibits the breakdown of other contaminants.Therefore,it is significant and urgent to study degradation of quaternary ammonium salt cationic surfactant.In this thesis,a series of active nano-zinc oxide were prepared by microwave irradiation method and were used for photocatalytic degradation of CTAB.The main research contents and results are as follows.1.Nano-zinc oxide was synthesized by microwave assisted sol-gel method and characterized by XRD,SEM,TEM,UV-vis spectra,BET and photocatalytic property.The effects of microwave irradiation condition on the crystal structure,micro morphology,absorptivity of ultraviolet and visible light,surface area and photocatalytic property of zinc oxide were studied.The mechanisms of the photocatalytic property of zinc oxide enhanced by microwave heating method and choosing suitable microwave condition were also discussed.As the experimental results suggest,the time consumption for sol-gel reaction is largely shortened by using microwave irradiation technique.However,the calcination process for precursor is necessary.The optimum preparation conditions of zinc oxide by microwave sol-gel method are as follows:microwave irradiation power of 800W,microwave irradiation time of 10min.The suitable photo catalytic degradation conditions are as follows:water solution of CTAB at the concentration of 0.4g/L of 50mL,dosage amount of zinc oxide at a concentration of 2g/L,pH of 9,reaction time of 90min,the degradation ratio of CTAB is91.0%.The degradation of CTAB using zinc oxide by microwave sol-gel method is first-order reaction,and the kinetic constant is 0.02611min^-1,which is higher than the kinetic constant of zinc oxide prepared by water bath heating(k=0.02341min^-1).2.Nano-zinc oxide modified with DEA was synthesized by microwave assisted sol-gel method and characterized by XRD,SEM,TEM,UV-vis spectra,BET and photocatalytic property.The effects of DEA amount on the crystal structure,micro morphology,absorptivity of ultraviolet and visible light,surface area and photocatalytic property of zinc oxide were studied.The mechanism of the photocatalytic property of zinc oxide enhanced by DEA modification was discussed.As the experimental results suggest,the optimum mole ratio of DEA to zinc acetate was 0.75.The suitable photo catalytic degradation conditions are as follows:water solution of CTAB at the concentration of 0.4g/L of 50mL,dosage amount of zinc oxide at a concentration of 2g/L,pH of 9,reaction time of 60min,the degradation ratio of CTAB is 89.8%.The degradation of CTAB using zinc oxide modified by DEA is first-order reaction,and the kinetic constant is 0.05025min^-1.3.Nano-zinc oxide was synthesized by microwave assisted precipitation method and characterized by XRD,SEM,UV-vis spectra,BET and photocatalytic property.The effects of microwave irradiation condition on the crystal structure,micro morphology,absorptivity of ultraviolet and visible light,surface area and photocatalytic property of zinc oxide were studied.The mechanism of the photocatalytic property of zinc oxide enhanced by microwave heating method and choosing suitable microwave condition were also discussed.As the experimental results suggest,the time consumption for precipitation reaction is largely shortened by using microwave irradiation technique,and the calcination process is unnecessary.The optimum preparation conditions of zinc oxide by microwave precipitation method are as follows:microwave irradiation power of 640W,microwave irradiation time of10min.The suitable photo catalytic degradation conditions are as follows:water solution of CTAB at the concentration of 0.4g/L of 50mL,dosage amount of zinc oxide at a concentration of 3g/L,pH of 9,reaction time of 60min,the degradation ratio of CTAB is85.6%.The degradation of CTAB using zinc oxide by microwave precipitation method is first-order reaction,and the kinetic constant is 0.02908min^-1,which is higher than the kinetic constant of zinc oxide prepared by water bath heating(k=0.02101min^-1).4.Nano-zinc oxide doped with Ce was synthesized by microwave assisted precipitation method and characterized by XRD,SEM,UV-vis spectra,BET and photocatalytic property.The effects of dopant amount and microwave irradiation condition on the crystal structure,micro morphology,absorptivity of ultraviolet and visible light,surface area and photocatalytic property of zinc oxide were studied.The mechanisms of the photocatalytic property of zinc oxide enhanced by Ce doped and choosing suitable microwave condition were also discussed.As the experimental results suggest,photocatalytic property of zinc oxide enhanced by Ce doped.The optimum preparation conditions of complex zinc oxide by microwave precipitation method are as follows:the optimum mole ratio of Ce to zinc acetate was 0.35,microwave irradiation power of 800W,microwave irradiation time of 10min.The suitable photo catalytic degradation conditions are as follows:water solution of CTAB at the concentration of 0.4g/L of 50mL,dosage amount of zinc oxide at a concentration of 0.2g/L,pH of 9,reaction time of 60min,the degradation ratio of CTAB is 93.9%.The degradation of CTAB using complex zinc oxide is first-order reaction,and the kinetic constant is 0.05789min^-1.