Fly ash based ceramic microfiltration membranes for oil-water emulsion treatment: Parametric optimization using response surface methodology

This article addresses the fabrication of ceramic microfiltration membranes (M1-M3) with uni-axial dry compaction method and fly ash, quartz and calcium carbonate as inorganic precursors. Raw material and membrane characterizations were conducted using particle size (PSD), thermo gravimetric (TGA), X-ray diffraction (XRD), scanning electron microscope (SEM), mechanical stability, chemical stability, porosity, pore size and pure water permeability analyses. Dead-end flow microfiltration (MF) experiments were conducted to evaluate the membrane performances with 50–200 mg/L synthetic oil-water emulsions. The MF experiments enabled to evaluate (M1-M3) membrane performance in terms of flux and rejection for variant combinations of feed concentrations and applied pressures. Among all membranes, M2 membrane demonstrated superior rejection (80.82–99.99%) and membrane flux (0.337–4.42 × 10⁻⁴ m³/m² s). Response surface methodology (RSM) via central composite design (CCD) was employed to optimize and understand the interaction of possible influencing process variables on the treatment efficiency in terms of flux and rejection. The optimum parametric conditions are found to be at an applied pressure of 345 kPa and feed concentration of 176.07 mg/L at which M2 membrane exhibits a maximum oil rejection of 97% with permeate flux of 2.6 × 10⁻⁴ m³/m² s.