Influence of pre-treatment temperature of palm oil fuel ash on the properties and performance of green ceramic hollow fiber membranes towards oil/water separation application

Palm oil fuel ash (POFA) is one of the most abundant industrial wastes in palm oil producing countries like Indonesia and Malaysia. Due to its unique characteristics such as high silica and hydroxyl group contents, it has high potential to be used as the main material for the fabrication of low cost and green ceramic hollow fiber membrane. This work investigated the effect of pre-treatment temperature of POFA towards the properties of the derived ceramic hollow fiber membranes. The properties of POFA such as morphology, mineralogical and chemical composition, thermal behavior, surface and pore properties were analyzed through scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray fluorescence (XRF), carbon element analysis, energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and nitrogen (N2) sorption technique. Effect of POFA pre-treatment temperature on the membrane properties were evaluated and characterized in terms of morphology, bending strength, pore size distribution, porosity and pure water flux (PWF). Finally, the separation performance of the membranes was also investigated using oil/water emulsion filtration tests. The results showed that the membrane properties were significantly improved for the membranes derived from pre-treated POFA compared to the untreated one. The highest bending strength of ∼60 MPa was achieved for TP700 membrane which was pre-treated at 700 °C. However, the PWF decreased from 219.2 to 28.4 L/m2 h for untreated POFA (UP) derived and TP700 membranes, respectively. Besides, an enhanced oil/water separation performance was obtained for membranes fabricated from pre-treated POFA with the highest oil rejection of 88.9%. These results showed that POFA derived ceramic hollow fiber membrane could provide the basis for the development of low cost and green ceramic hollow fiber membranes from waste ash for separation applications.