Process for Preparation of Low Cost Clay-Alumina Multichannel Ceramic Membrane for Liquid Filtration Application

Abstract

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 40°C 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 1600°C, were found to be 2.5 µm and 42%, whereas those for clay alumina tube, fired at 1450°C, were 1 µm 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