Novel silica sand hollow fibre ceramic membrane for oily wastewater treatment

Hollow fibre ceramic membranes are well-known to have unique characteristics, including superior thermal, chemical, and mechanical stabilities. The main drawback of ceramic membranes that limits their commercialisation is their high cost of raw materials. To overcome this disadvantage, a low-cost silica sand-based hollow fibre ceramic membrane (SS-HFCM) was successfully fabricated via combined phase inversion/sintering technique. Prior to fabrication, silica sand powder was first characterised using X-ray fluorescence (XRF), X-ray diffraction (XRD), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), and Fourier transform infrared spectroscopy (FTIR) analyses. Furthermore, the morphology and mechanical strength were investigated using scanning electron microscopy (SEM) and three-point bending test, respectively. The effects of two major fabrication process parameters (i.e., sintering temperature and ceramic content) on the mechanical strength, morphology, pure water flux (PWF), and oily-water separation of the SS-HFCM were examined. Based on the findings, the most suitable sintering temperature was 1300 °C. Satisfactory morphological structure and strength of sponge- and finger-like voids at 55 wt% ceramic powder loading was found to be advantageous for the characteristics of the fabricated SS-HFCM. The mechanical strength of 210 MPa was obtained at the sintering temperature and content loading of 1300 °C and 57.5 wt%, respectively. The mechanical strength of SS-HFCM obtained at 1300 °C in this work is significantly higher than those reported in previous studies. Furthermore, enhanced oil-water separation performance was obtained with the highest oil rejection rate of 99.7%. This SS-HFCM has a satisfactory structure with functional inner and outer layers of separation, which can be beneficial for water treatment applications, such as microfiltration, ultrafiltration, membrane distillation, and membrane contactor.