Morphological study of yttria-stabilized zirconia hollow fibre membrane prepared using phase inversion/sintering technique

This work describes the preparation of yttria-stabilized zirconia (YSZ) hollow fibre membranes using the phase inversion and sintering process. The study aims to provide generic information on the effects of membrane preparation on the morphology and mechanical properties of YSZ hollow fibre membranes. In this work, ceramic suspensions were prepared by mixing YSZ particles, dispersant, polymer binder and organic solvent using a planetary ball milling machine. This process was followed by extrusion into a coagulation bath via an air gap, drying and sintering process at temperatures ranging from 1250 °C to 1400 °C. The results show that by varying the YSZ loading and YSZ/PESf ratio, different morphologies of ceramic hollow fiber membranes can be obtained due to variations in the viscosities of ceramic suspensions. Similarly, air-gap length between the spinneret and coagulant surface was found to affect the growth of the finger-like structures and sponge-like regions. Varying these parameters also gave significant effects on the mechanical strength of the ceramic membrane due to the change in membrane thickness and compactness. The sintering process had insignificant effects on the membrane morphology but the process can be used to enhance the mechanical strength of ceramic hollow fiber membranes. The optimum temperature of the sintering process was identified. It was found that increasing the sintering temperature further caused a reduction in the mechanical strength due to crack formation in the ceramic hollow fiber membrane. The preliminary performance tests showed that the ceramic hollow fiber membrane sintered at 1300 °C has a pure water flux of 118.4 L/m2 h. It also has a high PEG rejection with molecular weight cut off (MWCO) of 60 kDa.