| A low cost 21 channel ceramic membrane was developed by extrusion and sintering process by mixing cheap
natural mineral, clay, with alumina. Two types of ceramic paste were prepared for preparation of multichannel
tubes for comparative study. Paste 1 was prepared from alumina and organic binder, methocel, along with water,
and paste 2 was prepared from clay and alumina along with methocel and water. Both the pastes were extruded
through multichannel die by plunger type hydraulic extruder to prepare 21 channel green tubes. The green tubes
were dried in a conventional way by drying it over alumina channel for 72 h, and in a controlled atmosphere by
rotating it over a roller at 18 rpm inside a closed chamber kept at 70% relative humidity and 40oC for 48 h. Both the
dried alumina and clay-alumina tubes were sintered in (a) vertical hanging, (b) horizontal and (c) angular supported
conditions in top hat furnace and the final tubes were compared and inspected for physical defects, viz. cracks and
warps to find the optimum processing conditions. The average pore size and porosity of alumina tube, fired at
1600oC, were found to be 2.5 m and 42%, whereas those for clay alumina tube, fired at 1450oC, were 1 m and
39% respectively. Maximum pure water flux obtained were 756 and 462 L.m–2.h–1 at 1 bar for alumina and clayalumina
tubes respectively.
[Keywords: Multichannel membrane, Porous tube, Clay-alumina, Membrane preparation] |
