Study On The Compatibility Of PES/PEI Blend And The Adsorption Performance Of MCM-41 Doped Hollow Fiber Membrane For VOCs

Volatile organic compounds(VOCs)have been recognized as one of the major hazards that seriously affect the environment and human health.It is of great significance to control VOCs at the industrial level for environmental protection.In this thesis,polyethersulfone(PES)/polyetherimide(PEI)blend hollow fiber membranes were prepared by the impregnation phase inversion method(NIPS),and the structure,properties,and compatibility of the blend membranes were investigated.Then MCM-41 molecular sieve was selected as the doped inorganic material to prepare PES/PEI/MCM-41 hollow fiber membrane adsorption materials.The adsorption performance of hollow fiber membrane materials was tested by simulating VOCs gas with a mixture of nitrogen and liquefied petroleum gas.(1)Through the combination of the characterization test and theoretical calculation,it was found that PES/PEI were partially compatible in the range of 75/25wt.%.The intermolecular interactions(hydrogen bonds,stacking)between the two polymers can promote compatibility.In terms of actual performance,the blending modification of PEI effectively increased the tensile properties of the blend film and changed the pore structure.The tensile strength increased by 38.34%,and the elongation at break increased by 3.54%.The cross section of the hollow fiber membrane was extended from the middle sponge-like region to the finger-like pore structure,and finally the sponge-like region disappeared.(2)Different proportions of MCM-41 were incorporated into the best blending ratio of PES/PEI(90/10 wt.%)to prepare hollow fiber membranes.The appearance of the characteristic absorption peak of MCM-41 in the infrared spectrum and the combination of SEM image observation and specific surface area and porosity analysis effectively prove that MCM-41 has been successfully doped on the pore wall of the polymer film.The specific surface area of the membrane increased from 9.89m~2/g to362.462m~2/g,and the average pore size decreased from 9.76nm to 3.50nm.The increase in adsorption sites and the rich pore structure have a positive effect on improving the adsorption effect of VOCs.(3)The prepared PES/PEI/MCM-41 hollow fiber membrane was used to test the adsorption performance of VOCs.The results showed that the adsorption performance of MCM-41 hollow fiber membrane(MPP-55)with a 55%doping amount was the best.Through breakthrough curve analysis and Yoon-Nelson model nonlinear fitting,it was proven that the adsorption effect of adsorption materials on heavy hydrocarbons was better than that on light hydrocarbons,and the breakthrough time was increasing.The physical monolayer adsorption process of propane on MPP-55 hollow fiber membranes was well described by Langmuir and Freundich models.The maximum adsorption capacity(73.386 mg/g)was determined by the volume of micropores and mesopores.