Study On Preparation And Coating Technics Of Polyethersulfone Gas Separation Hollow Fiber Membrane

Hollow fiber membranes have many advantages such as high packing density,good self-supporting and large effective membrane area per unit volume,etc.,It has a wide range of applications in the field of gas separation,water treatment,organic solvent separation and so forth.The choice of membrane material is the key to membrane separation process.Polyethersulfone(PES)was selected as the membrane material because of its excellent thermal stability,chemical stability and mechanical properties.In this study,we investigated the spinning parameters of high selectivity PES gas separation hollow fiber membrane and membrane module coating technics.Detailed research contents are given as follows:(1)PES dense film was prepared by solution casting technique.We measured gas permeability of N2,O2,CH4 and CO2 and calculated the ideal selectivity of O2/N2,CO2/N2 and CO2/CH4 gas pairs.(2)Viscosity of the PES dope solution was theoretically analyzed to determine the conditions for preparing the high selectivity PES hollow fiber gas separation membrane,including the composition of the dope solution and the spinning temperature.(3)PES hollow fiber membrane with almost defect-free surfaces at low temperatures was spun by dry-jet wet spinning.Effects of coagulation batch temperature,dope solution temperature and bore liquid flow rate on membrane morphologies and gas separation performance were investigated.PES hollow fiber membranes spun at the lowest temperatures(coagulation bath temperature:7 ℃,dope solution temperature:3 ℃),after silicone coating,the selectivities for O2/N2,CO2/N2,and CO2/CH4 gas pairs is 7.24,47.7,and 39.4,respectively.The membrane selectivity to O2/N2 gas pair is similar to the intrinsic selectivity of the PES dense film.Also,the selectivities to CO2/N2 and CO2/CH4 gas pairs are slightly higher.(4)Membrane modules were prepared for PDMS coating experiments.We investigated the effects of PDMS concentration,coating time and vacuum treatments on the separation performance of membrane module.The results showed that membrane module exhibited good gas separation performance by applying vacuum in membrane bore sides and circulating PDMS coating solution at membrane shell sides during coating process.