Study On Removal Of Multi-scale Pollutants By Bifunctional Electrostatic Spinning Fiber Membrane

In this thesis,a dual-function electrospun fiber membrane has been developed to meet the need of simultaneous removal of multi-scale pollutants in the water environment,which cannot be efficiently removed by the current single treatment technology.The hollow nano-carbon spheres,used as an adsorbent for the preparation of this fiber membrane,are effectively fixed by electrostatic spinning technology to form a blended fiber to realize the adsorption of small molecular pollutants.It is demonstrated that a blended fiber membrane with a uniform pore size can be obtained by adjusting the concentration of the spinning solution and the doping ratio of the nano-carbon spheres,thereby retaining large particles.Meanwhile,the static adsorption and recycling performance of the blended fiber membranes on the small molecule organic matter bisphenol A(BPA)were investigated by conducting the experiments of the adsorption conditions and recycling regeneration.The retention effect of large particles represented by polystyrene microspheres was also studied by performing the dynamic retention,flux regeneration,and pore size analysis of the blended fiber membranes.Additionally,the practical application performance of blended fiber membranes was evaluated by the simultaneous removal of bisphenol and polystyrene microspheres and the removal effect under different water quality background conditions.The conclusions are summarized as follows:1.The hollow nano-carbon spheres were fixed in polymer nanofibers represented by polyacrylonitrile(PAN)using electrostatic spinning technology.A blended fiber membrane with dual-functions of retention/adsorption has been successfully prepared by adjusting the polymer concentration,the doping ratio of the hollow nano-carbon spheres,and the external spinning environment.It is found that the blended fibers within 2μm have been obtained under the conditions that the spinning solution concentration of 24% and the hollow nano-carbon spheres to PAN of 2:3 by controlling the operating temperature at the range of 30-35 °C as well as the humidity within 10-30% RH.2.Small molecules represented by BPA and large particles represented by polystyrene microspheres were selected to investigate the adsorption capacity and retention performance of the blended fiber membranes.It is demonstrated that the maximum adsorption capacity of the blended fiber membrane after normalizing BPA can reach 200 mg/g by the static adsorption and cyclic regeneration experiments,and its adsorption efficiency remained above 85% after 5cycles.In addition,in terms of retention performance,the dynamic retention of ethylene microspheres can reach 100%,and its flux regeneration can reach 90%,hindering the formation of a filter cake layer on the membrane surface.3.2mg/L BPA and 25mg/L polystyrene microsphere blend solution were chosen to evaluate the simultaneous removal performance for multi-scale pollutants.300 L of the blended solution with BPA 0.01mg/L as the penetration concentration can be effectively treated by the blending fiber membrane per unit area when the peristaltic pump was working at 0.1 rpm and the entire polystyrene microspheres was retained.At the same time,a flux of 160 L of mixed solution can be effectively handled under natural water background conditions.Consequently,it can be concluded that the electrospun fiber membrane developed in this thesis is expected to provide a new technical approach for the simultaneous removal of multiscale pollutants under low pressure.