Experimental studies on pore size change of porous ceramic membranes after modification

• Published in: Journal of membrane science 1993-04, Vol.79 (1), p.65-82
• Main Authors: Lin, Y.S., Burggraaf, A.J.
• Format: Article
• Language: English
• Subjects: ceramic membranes; Chemistry; Colloidal state and disperse state; Exact sciences and technology; gas separations; General and physical chemistry; membrane modification, pore size change; membrane preparation and structure; Membranes
• ISSN: 0376-7388; 1873-3123
• DOI: 10.1016/0376-7388(93)85018-R

Experimental results on pore size change of a microfiltration (MF) α-alumina membrane and an ultrafiltration (UF) γ-alumina membrane after modification by chemical vapor deposition (CVD) of solid oxides in the membrane pores are presented and explained using the results of a theoretical analysis. With an approx. 10-fold reduction in permeability, the average pore size of the MF membrane is found to increase after CVD modification, due to its relatively broader initial pore size distribution with a small amount of large pores and due to the particular CVD conditions (heterogeneous deposition mechanism) which give a pore narrowing rate independent of pore size. The effective pore size of the UF membrane appears to remain unchanged after modification with an approx. 50-fold reduction in permeability, as a result of the slit-shaped pores of the γ-alumina film and the particular modification conditions. The experimental and theoretical results suggest that, in order to reduce effectively the average pore size of a membrane by a modification process, the membrane should have a rather uniform pore size distribution, or the modification process should be conducted under conditions which give a pore narrowing rate proportional to the pore size.