Preparation and characterization of polyamide nanofiltration composite membranes with TiO 2 layers chemically connected to the membrane surface

A polyamide (PA) nanofiltration (NF) composite membrane with TiO 2 layers was designed and prepared, in which the TiO 2 layers were chemically linked to the crosslinked polyamide layers of the membrane. In this study, TiO 2 , one of the well known photo‐catalysts effectively degrading organics with UV light, was introduced to the PA NF membrane by using 3‐aminopropyltrimethoxysilane (APTMOS), titanium (IV) isopropoxide (TIP) to improve its antifouling property. In particular, for this membrane, SiO 2 layers were formed between the TiO 2 layer and the crosslinked polyamide layer of the membrane to protect the organic parts of the membrane from the TiO 2 catalyzed UV degradation. The prepared membrane with TiO 2 layers was then characterized using several analytical methods: scanning electron microscopy (SEM), X‐ray photoelectron spectroscopy (XPS), x‐ray diffraction (XRD) and permeation tests. It was found that the prepared membrane was stable; especially the TiO 2 layer of the membrane was found to be stable after several times of use for permeation test. The membrane showed a typical NF property, despite of the presence of the TiO 2 layer. From long time tests with or without UV light, it was found that there was good antifouling effect on the membrane by the TiO 2 layer. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007