Alumina Membranes

Abstract

Alumina membranes are membranes made of high-purity (mostly >97 %) aluminum oxides (alumina). They belong to the categories of ceramic membranes and in most cases, microfiltration and ultrafiltration membranes. Pure alumina membranes are predominant in all kinds of commercial ceramic membranes, and most other commercial ceramic membranes, if using other materials as the separation coating, are based on alumina membrane support. Advantages and Disadvantages Alumina membranes are chemically inert and mechanically strong, and also thermally stable, therefore they can be used under very harsh con-ditions such as aggressive chemical environments and elevated temperatures, making them versatile in various industrial processes. Their strong mechanical properties allow them to be operated under high pressures and high feed flow rates to achieve high productivity and to tolerate high solid contents in the feed. The high fabrication cost is a major obstacle for alumina membranes to expand its market share. Although alumina is widely available, the com-plicated fabrication process and high energy con-sumption for sintering lift significantly the total membrane cost, making it about one order of magnitude higher than its polymeric counterparts. However, because of much longer lifetimes and higher fluxes of alumina membranes, the long-term operating cost of alumina membrane plants is comparable with polymeric membrane plants, no mention there are many scenarios in which only alumina/ceramic membranes can be used.