Performance of porous inorganic membranes in non-osmotic desalination

Abstract

The supply security of fresh drinking water is decreasing and raising a critical situation for communities worldwide. Inorganic membranes such as alumina and molecular sieve silica have in the past been shown to be highly effective at separating gases and could offer promise as liquid separators due to their high flux and stability. In this work, we develop a range of inorganic membranes with pore size ranging from 0.3 to 500 nm and relate this to separation and transport performance. Best separation results were achieved for the silica membrane pressurised to only 7 bar, exhibiting a flux of around 1.8 kg m-2 h-1 and NaCl rejection of 98% with 3.5 wt% (seawater-like) feed. Potable water from seawater-like feed was achieved from the membrane in a single stage after regeneration. Conditions such as pressure and temperature were also modified showing performance characteristics and diffusion mechanisms. The non-osmotic set-up for inorganic membranes is therefore a viable technology for desalination. © 2007 Elsevier Ltd. All rights reserved.