Co-sintered synthesis of needle-like mullite porous membrane materials

To reduce the production cost and improve the performance of new membranes a high permeability porous mullite membrane material was directly synthesized by designing a mesh structure formed from needle-like mullite. The kaolin powder with 65% Al2O3 content served as the precursor material for the porous mullite support, the powder doped 5 wt% AlF3 with 60% Al2O3 content served as the precursor material of the needle like mullite crystal layer. A thin layer of the precursor material of the needle like mullite crystal layer was coated on the support precursor. In the co-sintering preparation of the membrane the free SiO2 in the kaolin was consumed by the alumina precursors, AlF3 as additive promoted the formation of mullite whiskers, so that a mesh structure was formed in-situ, which imparted suitable permeability and selectivity to the final structure. The growth of mullite whiskers has a positive impact on the improvement of porosity and permeability of ceramic membranes. The water flux of the membrane increased by 1.2-2 times compared to the existing microporous membranes of the similar pore size. The porosity of the samples was greater than 47% between 1250 degrees C and 1400 degrees C as the sintering temperature was increased. This preparation process simplified the preparation of the bilayer membrane, and greatly decreased the cost of raw material and production time and improved the performance of the membrane product. The bilayer membrane developed in this study may be used as a microfiltration membrane, particularly in high-throughput water treatment applications.