Surface Modification of Alumina Membranes for Membrane Bioreactor

Abstract

Alumina membranes were modified by the chemical treatment using trimethylchlorosilane (TMS), octadecyldimethylchlorosilane (ODS), γ-aminopropyltriethoxysilane (γ-APS) and 1, 3-propane sultone (PS) to control the zeta potential and surface free energy. Silane coupling agents such as TMS, ODS and γ-APS reacted with surface hydroxyl groups of alumina membrane and formed Al-O-Si bondings. PS was also incorporated into alumina surface by Al-O-C bondings. Reacted amounts of TMS, γ-APS and PS with surface hydroxyl groups were estimated as -3 molecules/nm2 by elemental analysis, whereas ODS was found to be reacted with 1.0 OH/nm2 hydroxyl groups of alumina. It may be considered that reacted amounts are restricted by geometrical arrangements of ODS on the alumina surface. Zeta potentials of surface-modified alumina membranes were controled to be anodic and cathodic by the introduction of sulufo groups from PS and amino groups from γ-APS, respectively. Low energy surfaces were produced by the introduction of alkyl groups like TMS and ODS.