Defects in microporous silica membranes: Analysis and repair

A low temperature (300 °C) CVI technique was employed to modify commercial sol–gel silica membranes, in order to repair defects often formed in their top sol–gel layer. Membranes were characterized before and after modification in terms of permeance and permselectivity with the use of He and N2. The permselectivity of the sol–gel silica membranes varied between 3.2 and 52, while after the CVI treatment the permselectivity increased to 68–308. Moreover, a simple model was developed in order to estimate the defect concentration in silica membranes and assess their influence in the membranes performance.