Effects of membrane surface chemistry on fouling investigated using self-assembled monolayers

Abstract

Fouling is one of the key factors limiting the application of membrane processes. Recent studies have demonstrated that membrane fouling can be reduced by various surface modification techniques. However, the surface modification methods currently available often result in simultaneous changes in other membrane properties (e.g. reduction in pore size, damage to the base membrane, spatial non-uniformity in the degree of modification). These complications pose a challenge to quantitatively identify the key features in the surface modification that are needed to reduce fouling. Here a controlled surface modification technique without altering other membrane properties was applied to identify the surface chemistry required for developing fouling resistant membranes. We use self-assembled monolayers with various terminal functional groups including acid, alcohol, alkane, and tri(ethylene glycol) on silver membranes to investigate the effects of membrane surface chemistry on protein fouling. This method allows uniform coating of the internal pore structure with a monolayer of the modifier. The flux decline of the tri(ethylene glycol) terminated SAMs modified membrane is significantly reduced compared to the native membrane during bovine serum albumin (BSA) filtration. Other SAMs modified membranes also showed some minor effects on reducing the rate of flux decline. These results demonstrate a new approach to modify membrane surface chemistry for fouling investigation.