Optimization of extrusion parameters for low-cost alumina–kaolin ceramic membranes via CCD

This study investigates the effectiveness of central composite design (CCD)-based response surface methodology (RSM) in optimizing the extrusion method-based fabrication conditions of low-cost alumina-kaolin ceramic membranes. The RSM approach was validated by optimizing ceramic membrane fabrication based on composition and sintering temperature variations. Key fabrication parameters, including the compositions of alumina, kaolin, talc, starch, and polyethylene glycol (PEG), and the sintering temperature, were optimized to achieve the desired porosity, average pore size, and flexural strength. The study also examined the effect of two binders (starch and PEG) on these response variables. CCD analysis revealed that starch content was the most significant factor affecting membrane porosity, average pore size, and flexural strength. This optimal composition consists of 89.74 g (61.29 % by mass) of alumina, 24.59 g (16.79 % by mass) of kaolin, 1.85 g (1.26 % by mass) of talc, 19.84 g (13.55 % by mass) of starch, 10.40 g (7.11 % by mass) of PEG, a sintering temperature of 1049.49 °C. The optimal precursor composition resulted in a membrane porosity of 54.73 %, an average pore size of 1.935 μm, and a flexural strength of 3.15 MPa, with deviations of 2.26 %, 3.25 %, and 5 %, respectively, from the predicted values. These findings confirm that the RSM-based design model, incorporating porosity, average pore size, and flexural strength as response variables, is a robust tool for optimizing the fabrication of alumina-kaolin ceramic membranes. The characterization results of the fabricated membrane indicate that its physical and functional properties align with the typical range of microfiltration. This suggests its high potential for applications in microfiltration processes.