Design and fabrication of ceramic hollow fiber membrane derived from waste ash using phase inversion-based extrusion/sintering technique for water filtration

Low-cost green ceramic hollow fiber membranes (CHFM) were successfully designed and fabricated from the industrial waste ash, palm oil fuel ash (POFA) via phase inversion-based extrusion/sintering techniques for water filter application. The extrusion process parameters such as suspension viscosity, air gap distance, and bore fluid flow rate were systematically explored to produce the membrane with the desired morphology. A high suspension viscosity would result in a small macro-voids structure. Moreover, a high air gap distance would induce fiber with long macro-voids structure, while a low bore fluid flow rate would lead to the formation of distorted lumen structure. The effect of sintering temperature towards CHFM was also studied in detail. An increase in sintering temperature improved the membrane bending strength, but also adversely affected the pure water flux due to lower porosity and higher tortuosity. The developed membranes achieved excellent bending strengths of > 75 MPa at relatively low sintering temperatures than the alternative ceramic counterparts, due to its high potassium oxide, K 2 O content, which acted as the low melting point sintering aid. The relatively low sintering temperature of POFA-derived CHFMs could reduce the energy consumption and sintering duration, which could be more economically attractive, as compared to their ceramic counterparts, thus benefiting industrial users.