Effect of sintering temperature on functional properties of mullite-kaolinite and stainless steel composed hollow fibre membrane for oil-in-water emulsion separation

Background The commercialization of mullite-kaolinite hollow fibre HFMs is still obstructed due to the weakness of their mechanical strength. Methods This study investigates the effect of different sintering temperatures (i.e., 1350, 1400, 1450 and 1500 °C) on the mechanical strength and other functional properties of ceramic HFMs composed of mullite-kaolinite and stainless steel (SS). The membranes were tested and evaluated through an oil-in-water separation process using three oily emulsions (i.e. 1000, 1500, and 2000 ppm) in a filtration system for 120 min. Significant findings The results showed a successful preparation for mullite-SS HFMs with asymmetrical and sponge-like structures. Increased sintering temperatures from 1350 to 1500 °C significantly integrated mullite and SS particles, and forming robust bonds improved the mechanical strength. Amongst all mullite-SS HFMs, the membrane sintered at 1450 °C was the most suitable for oil-in-water separation due to its optimum properties compared to other mullite-SS HFMs. As compared to mullite HFMs counterparts, the mullite-SS HFM at 1450 °C exhibited higher mechanical strength, oil rejection rate and permeate flux of 106.4 MPa, 99.05% and 345 L/m2.h, respectively. In addition, it showed higher mechanical stability and separation performance for a longer filtration time of 120 min than other CHFMs prepared from different low-cost materials reported in previous works. This membrane offers an advantage in mechanical strength, water flux, and rejection performance, making it suitable for various water treatment applications.