Effect of silica nanotubes on characteristic and performance of PVDF nanocomposite membrane for nitrate removal application

Abstract

In this work, impact of synthesized silica nanotubes (SNTs) on morphology and performance of polyvinylidene fluoride (PVDF) nanocomposite membrane was studied. For this purpose, SNTs were synthesized using hydrothermal method, characterized by different techniques, and finally used as filler in nanocomposite membrane preparation. The PVDF/SNTs nanocomposite membranes were fabricated via phase inversion method at different dosage of SNTs (1–6 wt.%). As-prepared membranes and SNTs were characterized by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS), and contact angle measurement. The results confirmed by incrementing SNTs dosage, hydrophilicity of PVDF membrane was increased. The effect of SNTs on the membrane performance was studied through nitrate removal at operating pressure of 7 bar. The results showed that the optimal performance parameters (nitrate rejection and pure water permeability (PWP) were obtained at SNTs dosage of 4%. The effect of feed concentration (50, 100, and 150 mg/L) on nitrate separation performance was also investigated and it was found that the maximum rejection of 86% and PWP of 11.58 (L/m2.h.bar) were achieved for optimum PVDF/SNTs membrane at 150 mg/L. Finally, antifouling properties of optimum PVDF/SNTs membrane were investigated.