| Membrane separation process of high separation efficiency,low operating costs,has been widely used in the water treatment industry.In recent years,membrane materials have become a hot topic in membrane separation.Polyethersulfone(PES)is a kind of polysulfone polymer,which is one of the most common membrane materials for phase transformation.Due to its advantages of heat resistance,chemical resistance,mechanical properties,hydrolysis stability and biocompatibility,PES has attracted much attention in the development and application of membrane separation materials.However,polyethersulfone membrane has the disadvantages of poor hydrophilicity and poor anti-pollution performance,which reduces the life of the membrane and limits its application in water treatment and other fields.Cellulose acetate has excellent hydrophilic properties and low price.In this paper,polyethersulfone/cellulose acetate blend membranes were prepared by using the blending method.The advantages of the two were combined to prepare membrane separation materials with excellent performance and low price.The main research contents and conclusions are as follows:In order to improve the anti-pollution and hydrophilicity of PES membrane,a series of asymmetric blend flat films were prepared by immersion precipitation phase conversion,cellulose acetate(CA,CDA,CTA)with different esterification degrees was used as the polymer additive and PES as the base membrane material.SEM was used to observe the microscopic morphology of the membrane,and the groups of the membrane were characterized by ATR-FTIR.The influences of the mass fraction of cellulose acetate and the degree of esterification on the mechanical properties,pore size,porosity,water contact angle,pure water flux,BSA rejection rate and pollutionresistance of the membrane were analyzed.The results showed that,after adding cellulose acetate,the tensile strength,hydrophilicity,pure water flux and pollution resistance of the three blend flat membranes were higher than the original membranes,but the elongation at break was decreased.At the 2.8% mass fraction of CDA,the blend flat membranes could get the best comprehensive performance with 0.2517?m of the mean pore size,0.2815?m of diameter,68.06° of water contact angle,85.44%of BSA rejection rate,60% of flux recovery rate,99.83L/(m2·h)of pure water flux,which is five times higher than pure PES membrane.Compared with the original membrane,the blend flat membranes with enhanced hydrophilicity,permeability and anti-pollution can be prepared by controlling the mass fraction and esterification degree of cellulose acetate.On the basis of the experimental conclusions in the second chapter,PES/CDA blend flat membrane was prepared by using PES and CDA as polymer raw materials,DMAc as the solvent and deionized water as the coagulation bath.The effects of the mass fraction of glycerin added in the casting solution and the type of alcohol on the structure and properties of the PES/CDA blend flat membranes were investigated.The morphology of the membranes was characterized and mechanical property,mean pore size,water contact angle and the pure water flux of the membranes were tested.The results showed that with the increase of the mass fraction of glycerol,the number of micropores on the membrane surface increased and the distribution became more uniform;while the finger-shaped pores of the membrane section gradually disappeared and the circular cavity structure began to appear.When 6.0wt% glycerol was added,the membrane could get the best comprehensive performance with0.2104?m of the mean pore size,0.2230?m of diameter,134.51L/(m2·h)of pure water flux and 79.61°of the water contact angle.With the same mass fraction,the pure water flux is found to be largest by using ethylene glycol as an additive;while the use of isopropanol as an additive demonstrated smallest water contact angle. |
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