Fabrication and Characterisation of a Novel Mullite-Stainless Steel Composed Hollow Fibre Membrane for Oil/Water Separation

Low-cost mullite-kaolinite material has recently received more attention as an alternative to conventional ceramic materials such as alumina and silica to prepare ceramic hollow fibre membranes (CHFMs) due to its high alumina contents and silica and thermal/chemical stability. However, weak bending strength is still one of the key bottlenecks that delay their commercial applications. In this work, we successfully fabricate a novel mullite-SS HFM with enhanced bending strength using mullite-kaolinite power with different stainless steel alloy (SS) 316 L contents of 0.0, 2.5, 5.0, 7.5, and 10% (w/w) as a reinforcement material by phase inversion/sintering techniques. The SS alloy was a potential material to enhance the mechanical strength of mullite HFMs due to its excellent mechanical properties. The effects of the major fabrication parameters of SS contents, mullite contents, fabrication parameters such as air gap distance, and bore fluid flow rates were well studied and evaluated through the fabrication process. Fabricated mullite-SS HFMs were characterised by morphology, porosity, pore size/pore size distribution, and bending strength. Afterwards, they were evaluated in an oil/water separation system regarding water flux and oil rejection rate. Based on the findings, an increment of the SS contents from 0 – 10% (w/w) improved the membrane morphology and crystallinity while reducing the porosity to 29 % (w/w). The satisfactory morphology with micro-void structure and higher crystallinity was obtained at 10 % (w/w) SS. The bending strength also improved to the highest value of 66.7 MPa at 10 % (w/w) SS due to additional bonding formation between SS and mullite particles at 1350 o C sintering temperature. This bending strength was significantly higher than that reported for mullite HFMs in previous works. Moreover, enhanced oil-water rejection performance was observed to attain about 96.9% by incrementing the SS contents from 0 – 10% (w/w), whereas water permeation was reduced to 290 L/m 2 . h due to pore size reduction by SS particles. These findings suggest the benefit of this membrane for various water treatment applications, such as oil/water separation, due to its outstanding physical properties.