Controlled Preparation Of ZnO Based Nanofibers And Their Denitrification Performance Of Photodegradable Fuel Oil

Nitrogen compounds in fuel oil Due to the efficient use of fuel oil,nitrogen oxides discharged into the atmosphere have seriously affected the environment.It has become a new trend to use non-toxic and low-cost photocatalytic technology to remove nitrogen from fuel oil.Three kinds of photocatalysts,namely ZnO nanofibers,p-CuO/n-ZnO heterojunction nanofibers and p-Zn Fe₂O₄/n-ZnO heterojunction nanofibers,were prepared by electrospinning method.The photocatalytic denitrification performance of the prepared nanofibers was investigated in detail using pyridine/n-octane solution as simulation oil.The main research contents and results are as follows:（1）The optimal synthesis conditions of ZnO nanofibers were investigated.Under the conditions of polyethylene pyrrolidone（PVP）concentration of 11 wt%,Zn（CH₃COO）₂concentration of 0.4 mol/L,voltage of 17 k V,receiving distance of 15 cm,calcination at 500℃for 2 h,the hexagonal wurzite crystal ZnO nanofibers were successfully prepared.When the concentration of pyridine is 100 ug/g and the dosage of ZnO nanofiber is 175 mg/L,the removal efficiency of pyridine can reach 60.8%after 60min under visible light irradiation.（2）Multiple CuO/ZnO heterojunction nanofibers with different CuO contents were prepared by using CuO and ZnO heterojunction structures.The degradation efficiency of p-CuO/n-ZnO heterojunction nanofibers on pyridine in fuel oil was tested by experiments.In the same system of photocatalytic degradation of pyridine,the degradation rate of MCu Zn-0.5（Cu/Zn molar ratio is 0.5at%）photocatalyst of pyridine is 92.9%.The main reason for the strong denitrification activity of CuO/ZnO heterojunction nanofibers is that the construction of heterojunction can effectively reduce the recombination of photogenerated electrons（e^-）and holes（h⁺）,allowing more e^-and h⁺to participate in the removal of pyridine respectively.Therefore,the photocatalytic denitrification ability of p-CuO/n-ZnO heterojunction is improved.Using free radical trapping experiments,it is speculated that h⁺produced by photoexcitation plays a leading role in the intermediate of pyridine formation reactants,and superoxide radical（·O2^-）plays a promoting role in the final mineralization of pyridine.（3）In order to further improve the photocatalytic denitrification performance of ZnO nanofibers.In addition,p-Zn Fe₂O₄/n-ZnO heterojunction nanofibers were prepared.MFe Zn-53(the molar ratio of Zn²⁺:Fe³⁺is 5:3)has the best photocatalytic performance.In the same system environment,the degradation rate of pyridine can reach 96.1%.Compared with pure ZnO nanofiber,it is increased by 35.3%.This is because the formed p-Zn Fe₂O₄/n-ZnO heterojunction has a good absorption of visible light,which broadens the spectral response range of p-Zn Fe₂O₄/n-ZnO heterojunction nanofibers.In addition,the construction of heterojunction helps to reduce the separation of h⁺and e^-,thus improving the photocatalytic denitrification performance in the visible light region.