Photocatalytic removal of nitrate using TiO₂/polyacrylonitrile nanofiber membrane synthesized by co-electrospinning process

The present study investigates the development of titanium dioxide (TiO₂)/polyacrylonitrile (PAN) nanofiber membrane for the removal of nitrate from aqueous solution by photocatalysis. The TiO₂ nanoparticles were synthesized by conventional sol–gel method followed by blending them into PAN polymer. The blended solution was electrospun into nanofiber using the co-electrospinning technique. The nanoparticle, PAN nanofibers and the TiO₂ impregnated nanofibers were characterized using suitable techniques like X-ray diffraction, high-resolution transmission electron microscopy and scanning electron microscopy attached with energy dispersive X-ray spectroscopy. The average size and the diameter of the TiO₂ nanoparticles and TiO₂/PAN nanofibers were found to be 22 ± 0.32 nm and 90 ± 15 nm respectively. TiO₂ nanoparticles and TiO₂/PAN nanofibers showed maximum nitrate removal of 74.67 and 39% respectively at 10 mg/L nitrate concentration at pH 4. However at higher concentration (50 mg/L), the nitrate removal was found to be only 16.87%. The experimental data were fitted onto pseudo second-order kinetic model. The impregnation of TiO₂ nanoparticles into the PAN nanofibers by co-electrospinning techniques lead to higher removal of nitrate in aqueous solution at lower concentration (10 mg/L and below). However at higher concentration, the TiO₂/PAN nanofiber membrane was inefficient to remove nitrate.