Preparation Of MOF/Hollow Fiber Composite Membrane And Its Performance Research

UiO-66 is a kind of MOFs consists of zirconium ion linked with1,4-benzenedicarboxylic acid?H₂BDC?.Its aperture is around 0.6 nm and it has high thermal stability and chemical stability,which make UiO-66 promising candidates for membranes preparation.However,the growth characteristics of UiO-66 make it difficult to grow to a continuous membrane,and the strict requirements on the membrane preparation increase the probability of failure in fabricating UiO-66 membrane.Yttria-stabilized zirconia?YSZ?is a new ceramic material with Zr⁴⁺as same as UiO-66.The YSZ hollow fiber membranes can be used as substrates and contribute to inducing the growth of UiO-66 membranes.Besides,ceramic hollow fiber membranes have high chemical stability and thermal stability,high bending strength,high theoretical area/volume ratio and packing density.In this paper,YSZ hollow fiber membrane were prepared by using YSZ nanoparticles and polysulfone polymers as raw materials,using combined phase inversion method and high temperature sintering method.Bubble point pressure,pure water flux and bending strength of the membrane samples prepared at different sintering temperatures and YSZ contents were measured.The morphology of the membrane was characterized by scanning electron microscopy?SEM?.The effects of YSZ content and sintering temperature on the microstructure and properties of the prepared hollow fiber membrane were investigated.The results show an asymmetric structure of YSZ hollow fiber membrane containing finger-like structure and sponge-like structure.The YSZ content impacted the ratio between finger-like structure and sponge-like structure,and sintering process caused a densification of microstructure.Under the conditions of m?YSZ?:m?PSF?:m?NMP?=5:1:4,sintering temperature of 1200oC,the pure water flux was 2334 L·m^-2·h^-1·MPa^-1and the bending strength was 134.5 MPa.And then,YSZ hollow fiber membrane with the best preparation conditions were used as the substrates.UiO-66 membranes were prepared by in situ synthesis,which selected zirconyl chloride octahydrate and zirconium n-propoxide solution as zirconium metal source,respectively.The results show that the activated YSZ hollow fiber membranes can provide nucleation and anchoring sites for the deposition and growth of UiO-66 membranes by producing a Zr source for the formation of the UiO-66 structure,favoring the formation of high quality UiO-66 membranes.Besides,prolonging the formation time can also make the UiO-66 membranes thicker and more crystalline.48-hour formation time can fabricate UiO-66 membranes with a thickness of 5?6?m.Also,UiO-66 membranes selecting zirconium n-propoxide solution as zirconium metal source,can be fabricated in room temperature and the best formation time can be shortened in 24 h.