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

Abstract

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.