Preparation of Crack-Free Nanocomposite Ceramic Membrane Intermediate Layers on ?-alumina Tubular Supports

The objective of this work was to develop a crack-free membrane intermediate layer on tubular ceramic supports via dip-coating. TiO2 submicron powder, Boehmite as a coupling agent, and SiO2 nanopowder as low melting-point sintering aid were used to deposit a thin and crack-free nanocomposite layer onto a-Al2O3 supports. Effects of key parameters such as solid content, number of coated layers, the presence of coupling agent, and a low melting point nanopowder on physicochemical properties like the thickness, microstructure, pore size, pure water flux, and gas permeance of the final modified ceramic supports were investigated. The obtained results showed that after twice coating of support in 3 wt.% bidispersed TiO2-Boehmite suspension, the pore size of the alumina substrate, 0.6 micron, was reduced to 0.1 by the uniform membrane intermediate layers with low permeation resistance could be prepared. Moreover, by adding SiO2 nanopowder, sintering temperature of intermediate layers decreases considerably (1000 to 700C).