Preparation And Water Treatment Performance Of ZnO Electrocatalytic Separation Membrane

Membrane separation is an environmentally friendly and low-cost water treatment technology.However,the development of membrane separation technology is limited by low separation efficiency and serious membrane pollution in various water treatment and purification processes.A multifunctional separation membrane with electrocatalytic ability was prepared by combining electrocatalysis with membrane separation technology.The active oxygen species produced in the electrocatalysis process was used to mineralize and decompose the organic pollutants in water.The membrane separation efficiency was improved and membrane pollution was effectively alleviated.This method has a wide range of research prospects.However,most researchers have focused on the photocatalytic properties of zinc oxide（ZnO）composite films up to now,while the electrocatalytic properties of ZnO composite films have been less investigated.At the same time,the efficiency of electrocatalysis is much higher than that of photocatalysis in terms of the degradation of dyes,so it is of great significance to investigate the electrocatalytic performance of ZnO composite film.In this work,the composite material rGO-ZnO of ZnO and rGO was successfully prepared with one-step hydrothermal method,and the conductive membrane of rGO/ZnO/PSF mixed matrix was prepared with phase transformation method.The influence of rGO-ZnO contents on membrane performance was analyzed by testing its hydrophilicity,selective permeability and antifouling properties.When the amount of rGO-ZnO was 1.5 wt%,the flux of mixed matrix membrane was 296 L·m^-2·h^-1·bar^-1,which was higher than 128 L·m^-2·h^-1·bar^-1 of pure PSF membrane.At the same time,the removal rates of CR,Rh B,MO and MB by rGO/ZnO/PSF films under applied electric field were as high as 99.4%,84%,94%and 93.3%,respectively.In addition,the mixed matrix membrane has satisfactory anti protein pollution performance,and the recovery rate of water flux is 93%.Through the analysis of the relationship between the microstructure and properties of the mixed matrix membrane,the results show that the addition of rGO-ZnO can effectively improve the hydrophilicity of the membrane surface and the size of pores,and endue the electro-catalytic properties of the mixed matrix membrane,thus improving the separation efficiency and anti-fouling performance of the mixed matrix membrane.However,as part of ZnO was embedded under the polymer matrix during the phase conversion process,it cannot directly contact with the dye solution to be treated,so its electrocatalytic performance was somewhat reduced.In order to further improve the utilization rate of ZnO electrocatalytic performance and further improve the selective permeability of the membrane,the electrospun polyacrylonitrile（PAN）nanofiber membrane was used as the base membrane,and the ZnO functional layer was prepared on the base membrane with physical vapor deposition.The flux of PAN-ZnO composite nanofiber membrane was 1016 L·m^-2·h^-1·bar^-1.Meanwhile,under the action of applied electric field,the removal rates of CR,Rh B,YS,MO and MB by PAN-ZnO composite nanofiber membrane were as high as 99%,98%,97%,99%and 96%,respectively.In addition,PAN-ZnO composite nanofiber membrane has satisfactory mechanical strength,antifouling properties and electro-catalytic stability.