The characterization and water purification behavior of gradient ceramic membranes

In this paper, the characterization of gradient diatomaceous earth membranes prepared by centrifugal casting was investigated. The size of the ceramic particles change gradually from large to small along the radical cross-section of the tubular membrane, so the pore size of the tubular membrane change gradually from large to small along the radical direction. There are hundreds of layers of different size ceramic particles along the radical cross-section of the membrane tube. The gradient membrane offers high flux, high porosity with narrow pore size distribution and defect-free. The average pore size is 0.15 mum and the maximum do not exceed 0.3 mum. The water purification tests showed that this kind of ceramic membranes perform good behaviors: 100% of the pathogenetic bacterium such as E. coli, Salmonelle, microzyme, staphylotoxin, Pseudomonas aeruginosa and mold, etc. in water can be removed, and 100% of rust, worm and suspension particles in water also can be removed. The gradient ceramic membranes have a good flux efficiency recovery just by simple mechanical brushing. The tests showed that a gradient ceramic membrane filter in 225 mm length, 55 mm outer diameter and 7 mm thickness can filtrate more than 50 M-3 of drinking water. (C) 2003 Published by Elsevier Science B.V.