Alumina and aluminate ultrafiltration membranes derived from alumina nanoparticles

The fabrication of alumina ultrafiltration membranes using acetic acid surface stabilized alumina nanoparticles (A-alumoxanes) has been investigated. The pore size, pore size distribution, and molecular weight cut-off (MWCO) parameters of the resulting membranes are highly dependant on the uniformity of the nanoparticle precursor, which is a function of the reaction time and reaction pH during their synthesis. By the control over the alumina nanoparticles, a significant improvement of the membrane performance is observed over our prior results. The new alumoxane-derived membranes have a molecular weight cut-off in the range of < 1000 g mol(-1), and show good selectivity to a range of synthetic dyes. Further control over selectivity and flux of these ceramic membranes may be obtained by the use of doped alumina nanoparticles (Fe, Mn, and La) that result in the formation of the appropriate aluminate membranes. Of these, LaAlO3 shows the most promising results, with an increase in selectivity and increased flux as compared to the alumina analogue. Retention coefficients and flux values may also be altered by the chemical functionalization of the interior surface of the membranes by reacting the alumina surface with carboxylic acids. (C) 2003 Elsevier B.V. All rights reserved.