Simultaneous separation and degradation of methylene blue by a thin film nanocomposite membrane containing TiO2/MWCNTs nanophotocatalyst

Abstract

ABSTRACT An innovative photocatalytic thin film nanocomposite (TFN) membrane was prepared and used for the simultaneous separation/degradation of methylene blue (MB) under UV irradiation. For this purpose, we used the sol-gel method to prepare the TiO2/MWCNTs nanophotocatalyst and added to the 1,3-phenylenediamine (MPD) solution during interfacial polymerization (IP) of 1,3,5-benzenetricarbonyl chloride (TMC) and 1,3-phenylenediamine monomers on the polysulfone (PSF) support. Using scanning electron microscopy (SEM) analysis and studying the cross-sectional images of membrane samples, it was revealed that the polyamide (PA) thin layer was well fabricated over the support membrane. The attendance of the TiO2/MWCNTs nanophotocatalyst in the PA thin layer of TFN samples was also proved using EDX (energy-dispersive X-ray) analysis. According to the results of the contact angle (CA), it is clear that the hydrophilicity of membrane samples first increased and then decreased by enhancing the TiO2/MWCNTs nanophotocatalyst content in the PA thin layer. In comparison with the pristine thin film composite (TFC) membrane, TFN samples showed higher water flux and MB removal when they were exposed to UV light. Finally, it turned out that the TFN membrane comprising 0.2 wt. % TiO2/MWCNTs nanophotocatalyst (TFN 0.2) had the foremost efficiency among TFNs with the water flux of 13 L/m2·hr and dye separation/degradation of almost 100% under UV irradiation.