Preparation Of YSZ Hollow Fibre Membranes And The Effect Of Fe₂O₃ Doping On Properties Of YSZ Hollow Fibre Membranes

Having high chemical stability, thermal stability, high bending strength, high theoretical area/volume ratio, packing density and high separation efficiency, ceramic hollow fiber membranes(HFMs) used as the separation membrane or the membrane support exhibited a huge potential application in the separation of high temperature and corrosive liquids or the gas separation under high pressure. To achieve a proper bending strength for the practical applications, the ceramic HFMs need to be sintered at high temperature, however, which would sacrifice their pure water flux relevant to the separation efficiency and lead to a high production cost. Therefore, the conflictions caused by the bending strength, the pure water flux and the high production cost stuck the ceramic HFMs in a rut. In this study, the Fe2O3-doped yttria-stabilized zirconia(YSZ) hollow fiber membranes(HFMs) with high bending strength and pure water flux were fabricated by the phase inversion method and sintered at low temperature.Firstly, the effects of weight ratio of the solvent(NMP) and YSZ on the mechanical strength, pure water flux, microstructures were investigated to optimize the solution. Then the effect of Fe2O3 doping and sintering temperature on the bending strength, pure water flux, microstructures, porosity and pore size distribution of the YSZ-HFMs was investigated. Finally, the resistance to the corrosion solution of Fe2O3-doped YSZ-HFMs according to the Chinese standard GB/T1970-1996 was studied.The results suggest that the YSZ-HFMs with the weight ratio of the YSZ, the polymer(PES) and NMP being 5: 1: 4 sintered at 1250 oC/4hrs obtained the optimized bending strength(148±12 MPa) and pure water flux(545 L/m2?h). The increase of the ratio of the YSZ and PES impeded the diffusion of the non-solvent water forming the finger-like voids, leading to the thicker sponge-like region and the denser outer surface, thus improving of the bending strength and the decreasing the pure water flux of the YSZ-HFMs.The Fe2O3-doped YSZ-HFMs obtained high bending strength with less sacrifice in pure water flux relevant to the substantially narrow pore size distribution caused by the different diffusion mechanism of YSZ during the initial sintering stage inspired by the dissolved Fe2O3, which provided a new route to eliminate the confliction between mechanical strength and pure water flux. Remarkably, the 1.5 mol% Fe2O3-doped YSZ-HFMs sintered at 1150 oC/4h achieved the bending strength of 152±14 MPa and the pure water flux of 741 L/m2?h which was the best optimized performance in comparison to the other investigated ceramic HMFs. The pure/Fe2O3-doped YSZ-HFMs soaked in the acid/alkali solutions for 8h at 106±1 oC lose less than 0.6 wt.% mass that leaded to a ~10% loss of the bending strength. The volume fraction of monoclinic zirconia before and after the chemical corrosion remained unchanged.