Interfacial polymerization of polyamide-aluminosilicate SWNT nanocomposite membranes for reverse osmosis

A new method of single-pass flow which incorporates aluminosilicate single-walled nanotubes (SWNT) in a polyamide matrix was developed to fabricate thin film nanocomposite (TFN) membranes for low pressure reverse osmosis (RO) via interfacial polymerization. The TFN membranes were characterized using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) for the analysis of functional groups as well as composition of SWNTs. The typical morphology of polyamide layers was observed using atomic force microscopy (AFM) and scanning electron microscopy (SEM). The introduction of SWNTs in polyamide active layer is evident with the proliferation of aluminum and silicon elements from XPS analysis. All membranes show the rugose structure with “leaf-like” outgrowths and the “ridge-and-valley” structure commonly observed in polyamide RO membranes. The hydrophilicity was increased as observed in the enhancement in water flux and pure water permeance, due to the presence of hydrophilic nanotubes. With the incorporation of the single-walled aluminosilicate nanotubes, higher permeate flux was achieved while sustaining high rejection of monovalent and divalent ions, typical of polyamide RO membrane.