TiO2 nanotubes doped poly(vinylidene fluoride) polymer membranes (PVDF/TNT) for efficient photocatalytic degradation of brilliant green dye

Abstract

This study demonstrates the synthesis of highly hydrophilic poly(vinylidene fluoride) composite membranes incorporated with Titania (TiO2) nanotubes (PVDF/TNT) and then its photocatalytic applications were explored for effective degradation of brilliant green (BG) dye. The membranes were fabricated through phase inversion method using poly(vinylidene fluoride) (PVDF) as matrix, Titania nanotubes (TNT) with different concentrations (0–2 wt%) as filler and poly(vinylpyrrolidone) as pore former. Successful fabrication of composite membranes (PVDF/TNT) was confirmed by using X-ray diffraction analysis, Fourier transform infra-red spectroscopy, differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Membrane properties were studied using contact angle, tensile strength, solvent content, pure water flux, bovine serum albumin (BSA) rejection, antifouling properties, porosity and shrinkage ratio. The degradation results suggested that the fabricated membrane can effectively be applied as a heterogenous photocatalyst for the degradation of BG. The results confirm that the dispersion of TNTs increases the antifouling properties of membranes to a maximum value. A minimum pore volume 0.34 cc g−1, pore size 28.4 nm and maximum surface area 142 m2 g−1 were obtained with loading 1.5 wt% TNTs in PVDF membranes, which can degrade BG up to 42% compared to 13% in the absence of fabricated membrane after 90 min of reaction time. The photocatalytic degradation mechanism of BG by PVDF/TNT ultrafiltration membranes showed that OH is mainly involved in the degradation process. The degradation byproducts of BG were determined using LC–MS/MS and accordingly degradation pathways were proposed.