SILICA-ZIRCONIA MEMBRANES FOR NANOFILTRATION

Inorganic nanofiltration membranes were fabricated from silica-zirconi a composite colloidal sol (molar ratio Si/Zr=9/1) using a sol-gel proc ess. Molecular weight cut-off (MWCO) was successfully controlled betwe en 200 and 1000 Da by regulating the colloidal diameters of sol soluti ons in the final coating stage. The pure water permeabilities ranged f rom 0.15 x 10(-11) to 1.5 x 10(-11) m(3) m(-2) s(-1) Pa-1. Pore size a nd pore size distribution were estimated based on the dynamic method o f humid air permeation, and found to be from 1.0 to 2.9 nm. The MWCO o btained from NF experiments using neutral organic solutes corresponds well with the pore diameters estimated from the dynamic permeation met hod. Silica-zirconia membranes were found to be stable in aqueous solu tion for periods in excess of four months. (C) 1998 Elsevier Science B .V. All rights reserved.