Fabrication and properties of low cost ceramic microfiltration membranes for separation of oil and bacteria from its solution

This work addresses the development of low cost ceramic microfiltration membrane from inexpensive raw materials such as kaolin, quartz, calcium carbonate using uniaxial dry compaction method. The prepared membranes were sintered at different temperatures ranging between 900 and 1000 °C. The raw materials and the prepared membranes were characterized with thermogravimetric analysis (TGA), particle size distribution (PSD), X-ray diffraction and scanning electron microscope analysis. Subsequently, the effect of sintering temperature on the membrane properties such as porosity, flexural strength, chemical stability and pure water permeability was investigated and optimized for the sintering temperature. It is observed that with increasing sintering temperature, the porosity of the membranes decreases and the flexural strength, chemical stability and pure water permeability of the membranes increases. The flexural strength and chemical stability of the membranes are found to be excellent. Based on these results, the membrane sintered at 900 °C (porosity of 30%, flexural strength of 34 MPa, average pore size of 1.30 μm) is inferred as an optimum membrane for microfiltration applications. Solvent permeation studies have also been carried out for the membrane sintered at 900 °C and the results infer that the membrane is hydrophobic in nature. Further, the membrane is subjected to oil–water emulsion and bacteria separation experiments. The observed rejection decreased with an increase in the applied pressure and increased with an increase in the concentration of oil and bacteria, respectively. The results show a maximum rejection of 85% and 99% for oil (feed oil concentration of 250 mg/L) and bacteria (feed bacteria concentration of 6 × 105 CFU/mL), respectively.