Preparation Of Composite Nanofiber Membranes With ZnO Nanoparticles And Study On The Photocatalytic Performance

The polyacrylonitrile（PAN）/ZnCl₂ nanofiber membranes was prepared by electrospinning,which can act as precursors to fabricate PAN/ZnO nanofiber membranes by the method of solution impregnation.Moreover,methylene blue was taken as pollutant model to evaluate the photocatalytic degradation performance of the nanofiber membranes.In order to improve the photocatalytic degradation performance,pre-oxidation and carbonization of the nanofiber membranes were did.（1）PAN nanofibers were fabricated by electrospinning method with DMF as solvent,the optimum process parameters were as follows: the solution concentration is 12wt%;the voltage is 18 kV;the flow rate is 0.7 mL/h.By using the combined method of electrostatic spinning and solution impregnation method,I obtained the composite nanofiber membranes samples of R-11/1,R-7/1,R-5/1and S-5/1,of which R said repeatedly alternating immersion method,S show single hot/cold impregnation method.The morphology and microstructure of the nanofiber membranes were characterized by utilizing scanning electron microscope（SEM）,X-ray energy dispersive spectroscopy（XPS）,X-ray diffraction（XRD）,Fourier infrared spectrum（FT–IR）and thermal gravimetric analyzer（TG）,respectively.The results indicated that the sample of R-7/1 had the highest content of ZnO and its crystallization performance is best.By comparing the sample S-5/1 and R-5/1,the repeatedly alternating immersion method is better to made nanoscale ZnO clusters anchored on the surface of the nanofibers.（2）Then the methylene blue was taken as pollutant model to evaluate the photocatalytic degradation performance of the nanofiber membranes.It is shows that the sample of R-7/1 had the optimal degradation performance.The sample of R-7/1 and S-5/1 were used for three cycles of photocatalytic degradation test,and discovered that they all had a good photocatalytic properties and a good reuse performance.And some factors have influenced on the degradation rate of the nanofiber membranes,for example the smaller initial concentration of MB solution,the more amount dosage of catalyst,and in the alkaline dye solution the composite nanofiber membranes catalytic efficiency is higher.（3）Pre-oxidation and carbonization of the composite nanofiber membranes were did,the effect of pre-oxidation time and temperature and carbonization temperature of the composite nanofiber membranes were discussed,the results showed that when pre-oxidation time was 60 min,pre-oxidation temperature was 200 ℃,carbonization temperature was 1000 ℃,the morphology and structure was excellent.Then according to the optimal carbonization process of composite nanofiber membranes PAN/ZnO,found the diameter of sample of R-11/1 and R-7/1 were decreases,and ZnO particles on the surface were fall off seriously;although there were no obvious change about the diameter of sample of R-5/1 and S-5/1,less ZnO particles were fall off.After dealing with the carbonization process of composite nanofiber membranes,its photocatalytic performance are improved to some extent.