Slip Casting of Alumina for Membrane Application

Abstract

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% CaCO₃ plus 3% PVA. The water permeability was 150 L/m².h at 20 kPa and the hydraulic conductivity coefficient was 1.06 × 10^–9 – 2.43 × 10^–9 ms^–1Pa^–1. The density, linear shrinkage water absorption and 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 CaCO₃ 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.