Photocatalytic degradation of malachite green dye using nitrogen/sodium/iron-TiO2 nanocatalysts

Abstract

Enhanced visible light-responsive TiO2 modified with nitrogen, sodium, and iron was synthesized using an integration of green synthesis and wet impregnation method. The prepared nanocatalysts were characterized using some analytical tools like UV–visible spectrometry (UV–visible), photoluminescence (PL), High-resolution transmission electron microscopy, X-ray diffraction, Brunauer–Emmett–Teller N2 adsorption–desorption process, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy, The photocatalytic activity of N/Na/Fe–TiO2 and bared TiO2 for the degradation of Malachite green (MG) dye in aqueous solution under visible light was investigated. The response surface methodology (RSM) based on Box Benhken Design was used to evaluate the interaction between three important independent variables (reaction time, catalyst dosage, and dye solution pH). The XRD results of the prepared samples showed that the crystal phase was anatase irrespective of the modifiers. The BET surface areas of the tri-doped TiO2 nanocatalysts (80.165 m2/g) were higher than the undoped TiO2 (10.25 m2/g). XPS analysis confirmed the existence of Ti in + 4 oxidation states with or without the dopants. The MG removal efficiency was pH and catalyst dosage-dependent, and maximum MG degradation (96.57 %) was obtained using N/Na/Fe tri-doped TiO2 nanocatalyst under optimum experimental conditions of0.11 g catalyst dosage, 25.83 min reaction time, and pH of 9.89. The N/Na/Fe-TiO2 nanocatalyst was reusable for up to 5 cycles without significant loss of photocatalytic activity.