| With mass production and use of various drugs and personal care products,the pollution of pharmaceutical and personal pare products（PPCPs）in water environment is becoming more and more serious.In recent years,membrane separation technology has become one of the most popular and effective methods for the deep removal of PPCPs in water due to its low energy consumption,continuous separation,easy operation and high separation efficiency.However,existing separation membranes are facing some bottleneck problems in practical application,such as easy fouling and short life cycle.Therefore,it is vitally critical to develop high-efficiency separation membrane to promote the development of membrane separation technology for removal of PPCPs from water.In this dissertation,the selection of membrane material and design of membrane structure are highlighted.A highly stable and hydrophilic hollow fiber ceramic-graphene-oxide（GO）composite membrane was prepared with hollow fiber alumina ceramic as the membrane substrate,which possessed a good hydrophilicity and high mechanical strength,and GO as the active layer via surface modification method.Then membrane structure,water stability,permeability and salt rejection properties were characterized.In addition,a preliminary study in the removal of ibuprofen（IBU）from water was made.The work in this dissertation can be described briefly as follows:（1）Preparation and characterization of GO.Stable GO aqueous dispersion was prepared via modified Hummer’s method combined with ultrasonic techinique.The results from SEM,TEM and AFM showed that the resultant GO nanpsheets were mostly single layer with many wrinkles on its surface,and the thickness of GO nanosheets was about 1.2 nm.The results from FTIR,Raman,XPS and XRD showed that there were many oxygen-containing groups decorated on the planes and at the edges GO nanosheets,which endowed the excellent hydrophilicity and dispersibility.And the carboxyl group decorated at the edge of GO nanosheet easily hydrolyzed in water,and correspondingly making its negatively charged within a wide range of pH value（2-11）as characterized by Zeta potential test;（2）Preparation and structure optimization ofα-Al2O3 hollow fiber membrane substrate.In the present work,α-Al2O3 hollow fiber membrane substrate was prepared by phase inversion combined with high-temperature sintering technique.During the preparation process,the influence of air gap and composition of external coagulant bath on membrane pore structure,surface morphology,pore size distribution and water flux was mainly studied.The results showed that the ratio of finger-like void to sponge-like region could be simultaneously controlled by both air gap and composition of the external coagulation bath.The average pore size and porosity as well as water flux increased with the increases of air gap and content of ethanol in external coagulation bath.Based on a comprehensive assessment of pore size,porosity,mechanical strength and water flux,the hollow fiber membrane prepared with an air gap of 15 cm and 60 vol%ethanol as external coagulant bath was selected as the optimized membrane substrate.And the average pore size of 840 nm,surface porosity of 47.7%,and water flux of 1.4×103 LMH;（3）Fabrication and performance of hollow fiber ceramic-GO composite membrane for removal of IBU from water.Highly stable hollow fiber ceramic-GO composite membrane was prepared via vacuum filtration method with GO as the active separation layer,with optimizedα-Al2O3 hollow fiber membrane as the substrate,with dopamine（DPA）as the chemical surface modification agent,and with TMC as the cross-linking agent.Then the separation performance of the prepared composite memnbrane used for removal of IBU was studied.The results showed that the composite membrane modified with DPA and TMC exhibited remarkably enhanced water stability,and the intergrity of membrane structure was still retained after immersion in water even for four months.The thickness of GO layer had significant effect on membrane permeability,which could be controlled by varying filtration time.The water flux of the membrane with a GO layer thickness of 1.97 um was up to 12.37LMH,with a low rejection for monovalent salt ion but a high rejection for divalent salt ion(NaCl 43.6%,MgCl2 62.8%,and MgSO4 84.3%).The removal efficiency of IBU from water was more than 90%.And more importantly,both excellent fouling resistance and aqueous stability were obtained,which indicated that the ceramic-GO membrane obtained with DPA as the modified agent and TMC as the cross-linking agent had remarkably enhanced mechanical strength and superior hydrophilicity. |
