Fabrication and characterization of low cost tubular mineral-based ceramic membranes for micro-filtration from natural zeolite

Ceramic multilayer micro-filtration membranes with smooth surfaces and cracks-free have been fabricated on tubular porous supports by dipcoating using natural zeolite mineral as the starting materials. The preparation process, including the powder classification, the forming and sintering of membranes, was systematically studied. The membrane thickness was determined by dipping time and solid loading of the suspension. XRD reveals that the phase compositions of the membranes were related to the sintering temperature and the final major phases were almost quartz and albite. SEM studies subsequently indicate that solids in the membrane begun to sinter at about 850 degrees C with alkali metal oxides as the aid fluxes. The interlayers with average pore size in the range of 0.69-1.10 mu m were obtained and the optimum firing temperature was between 850 and 950 degrees C for I h. Then, the top-layer membrane with average pore size 0.54 mu m could be prepared on the above support. Nitrogen gas permeation flux and pure water permeation flux of the resulting membrane are 1.96 x 10(5) and 3.20 x 10(3) l m(-2) h(-1) X 10(-5) Pa-1 (1.96 x 10(5) and 3.20 x 10(3) l m(-2) h(-1) bar(-1)) with the trans-membrane pressure of 0.1 MPa at room temperature, respectively. (c) 2006 Elsevier B.V. All rights reserved.