Synthesis and Characterization of Cu and Se Doped TiO2 Photocatalysts and their Applications Against Glyphosate and Methyl Orange

Abstract

Advanced oxidation process in which TiO2-Catalyzed UV Oxidation reactions has emerged as promising wastewater treatment technique. TiO2 is most efficient photocatalyst because of its low dielectric properties, inert and chemically stable nature. In this thesis TiO2 in pure anatase phase was synthesized by using sol-gel method which is highly efficient and used to obtain purity of samples. After that to reduce band gap of TiO2 nanoparticles they were doped with Cu and Se ions in different ratios i.e. 1%, 3%, 5%, 7%, and 10 wt%. Precursors used for synthesis were TTIP, CuSO4.5H2O for Cu doping and SeO2 for Se doping. The nanocatalysts were characterized by XRD to find purity and phase, SEM for morphological analysis, BET to check surface area and pore size and EDS to determine the elemental composition. The Tauc plots were determined by taking absorbance from UV-Vis spectroscopy. Tauc plots of doped catalysts were significantly lesser than pure TiO2 which was due to introduction of impurity energy levels in TiO2 lattice. The degradation studies were carried out in presence of visible light using LEDs. Degradation studies of methyl orange and glyphosate were carried out using both the Cu doped TiO2 and Se doped TiO2. XRD spectra showed that crystallite size was decreased gradually from 21 nm to 11 nm as dopant level was increased and particle size was also reduced from 61 nm to 36 nm by adding different amounts of dopant. Efficiency of all the doped nanocatalysts were measured by taking absorbance after regular intervals of 3, 6, 9, 12 and 15 hours. And it was observed that doped samples of both Cu and Se series were showing better photocatalytic activity as compared to TiO2 NPs. And comparing all the doped samples, nanocatalysts with dopant concentration of Cu-7% and Se-7% were the best among all the other catalysts. Between the Cu-7% and Se-7% catalysts, Cu-7% was better than Se-7%. Reusaability of Cu-7% doped nanocatalysts was also studied and it was observed that these catalysts can be reused for atleast 3 times with more than 75% activities.