Characterization of flat ceramic membrane supports prepared with kaolin-phosphoric acid-starch

The purpose of this work is the development of microporous ceramic materials based on kaolin for a filtration process. Flat ceramic membrane supports were prepared from the mixtures of kaolin, phosphoric acid and starch. Porosity, permeability and mechanical properties of those supports were studied as functions of the amount of phosphoric acid, the sintering temperature and the compaction pressure. The rupture strength and the permeability of the ceramic membrane, increase with the content of phosphoric acid until 5 mass%. The porosity decreases with both the sintering temperature rise and the addition of phosphoric acid. The addition of 5 to 10 mass% of phosphoric acid and 10 mass% of starch to the kaolin supports sintered at 1100 °C for 2 h leads to a satisfied permeability and mechanical proprieties in the filtration application. The elaborated support was characterized using two analytical methods: DRX, 27Al and 31P MAS-NMR. The obtained analytical data indicate the presence of an AlPO4 high temperature phase at 1100 °C.