Preparation of hollow fiber NaA zeolite membranes by vacuum seeding method

Vacuum seeding method was proposed to solve the seeding problems existing in mass production of hollow fiber zeolite membranes.The α-Al 2 O 3 hollow fiber substrates were pre-coated with NaA zeolite seeds by a vacuum seeding method,then NaA zeolite membranes were synthesized by a secondary growth method on these substrates.NaA zeolite seeds and as-synthesized membranes were characterized by particle size analyzer,X-ray diffraction(XRD) and field emission scanning electron microscope(FESEM).The effects of seeding conditions on membrane quality were investigated to achieve optimal vacuum conditions.Results showed that the uniform seeding layer could be obtained under the conditions of 5 g / L seed suspension,vacuum degree of 10 kPa and coating time of 5 s.The as-synthesized hollow fiber NaA zeolite membranes exhibited excellent pervaporation performance.The permeation flux was 5.89 kg /(m2·h) and separation factor was 11 800 for the separation of ethanol solution with the mass fraction of 90% at 348 K.