Slip Casting of Alumina for Membrane Application

Porous alumina membranes were prepared from alumina matrix, polyvinyl alcohol binder (1-5%) and calcium carbonate additive (0-3%). The disc-shaped alumina samples were fabricated by slip casting process. The alumina paste was sintered at different temperatures of 1100,1200,1300 and 1400°C. The results showed that the porosity of the porous membrane reached 45%-46% at 1300°C sintering for the mixtures of alumina matrix with 3% PVA and alumina matrix with 2% CaC03 plus 3% PVA. The water permeability was 150 L/m2.h at 20 kPa and the hydraulic conductivity coefficient was 1.06 xx 10 -9-2.43x 10-9 ms -1Pa -1.The density, linear shrinkage water absorptionand mechanical strength were ca. 3.92 g/cm3,1.61-1.71% and 20.45-21.92%, 17.26-21 MPa, respectively. The SEM micrographs of alumina membrane using PVA binder showed a dense surface layers. An increase of the PVA binder resulted in a higher pure water fluxes and bigger pore sizes. An increase of CaC03 in a 3% PVA binder mixtures resulted in a little decrease of porosity but increase in linear shrinkage from 1.57 to 2.04% at 1300°C sintering.