This study presents an investigation of the purification of a raw diatomite by acid leaching conducted in hot solution (75 degrees C and 5 M HCl) for long periods up to 240 h. evaluates the use of these purified powders in the fabrication of porous materials, and examines their porosities. The treatment for 1 h increased the specific surface area of diatomite from 189 m(2)/g to 222 m(2)/g. but the SiO(2) content of 78.66% was still low. Material leached for a relatively short time shows an amorphous phase with quartz and plagioclase phases and the plagioclase is removable at longer leaching times during which no disruptive effect on the fine microscopic pores of the particles was observed. Thus, the diatomite based powders have potential use in the fabrication of porous coating as a membrane-separating layer: sintering at a relatively high temperature (1300 degrees C) still showed a significantly high apparent porosity of 48%. (C) 2009 Elsevier B.V. All rights reserved.