Preparation of porous ceramic membranes from Sayong ball clay

A porous ceramic membrane for the nano-filtration range was fabricated from a mixture of ball clay and starch. Sayong ball clay powders were mixed with starch as a pore former and compacted under a pressure of 200 MPa. The mixture was sintered at temperatures ranging from 900°C to 1200°C. It was found that the porous structure and crystalline phase of the sintered membrane were greatly dependent on the sintering temperature. The membranes exhibited bulk density varying from 1.5 g/cm3 to 1.9 g/cm3, an apparent porosity ranging from 40.2% to 0.34%, an average pore size of 23.16 to 5.11 nm and flexural strength ranging from 1 to 21 MPa as the sintering temperature was increased. The pore size observed by SEM is much larger than these values, and these observed pores are believed to construct open channels that act as the main paths for filtration, as discuss later. The permeation flux greatly dependent on the transmembrane pressure and sintering temperatures. The membrane synthesized at 1050°C displayed the optimum properties as a nanofiltration membrane with a bulk density of 1.6 g/cm3, apparent porosity of 18%, pore size of 9.84 nm and flexural strength of 6 MPa.