Assessment of Structural and Separation Properties of a PVDF/PD Composite Membrane Incorporated with TiO<sub>2</sub> Nanotubes and SiO<sub>2</sub> Particles
Mehrnaz Safarnia, Majid Pakizeh, Mahdieh Namvar‐Mahboub
Abstract
The current study focuses on the preparation of a polydopamine (PD)-modified PVDF membrane and its application for drug removal. The effect of adding an inorganic compound (TEOS) on the characteristics and performance of the PD/PVDF thin-film composite (TFC) membrane has also been investigated. For this purpose, the PD layer was coated using TEOS for in situ synthesis of a silica layer. The resultant membrane was coated at different dosages of as-synthesized TNTs to prepare thin-film nanocomposite membranes (TFN(S-T)). The prepared TNT, TFC, and TFN membranes were characterized by employing transmission electron microscopy (TEM), attenuated total reflection Fourier transform infrared (ATR-IR) spectroscopy, field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX), atomic force microscopy (AFM), ζ potential, and contact angle measurements. The results confirmed the formation of a hydrophilic nanocomposite layer with a negative charge. The separation performance of the as-prepared membranes was evaluated via diclofenac removal. The results revealed that diclofenac rejection increased from 81.5% for the PVDF membrane to 91.6% for the PD/silica/PVDF membrane with a permeability of 2.5 L/(m2·h·bar). In the case of the TFN(S-T) membrane, drug rejection increased to 93.2% at 0.1% TNTs and the permeability improved to 5.8 L/(m2·h·bar). Also, the effects of pH and feed concentration on diclofenac separation performance were studied. The results implied that the rejection of diclofenac increased from 93.2 to 95.6% with an increase in pH from 7 to 10.