RGO/N, Co-TiO2 Nanocomposites for Efficient Photodegradation of Methyl Orange

Abstract

In textile industries, different types of dyes are used widely. Widespread use of these dyes causes surface and ground water contamination. This contaminated water is harmful for the human beings and other organisms as well. Therefore, treatment of this contaminated water is really important. These dyes can be removed from waste water by using biodegradation but this method doesn‟t remove these dyes completely. Photodegradation has proved really successful in converting these toxic compounds to non-toxic or less toxic compounds e.g. CO2 and H2O. In this work, nanoparticles of un-doped and doped TiO2 were synthesized by sol-gel method. For the synthesis of undoped TiO2 nanoparticles, TTIP, 2-propanaol and distilled water were used. Whereas, for nitrogen and cobalt doping, urea and cobalt nitrate were used along with TTIP, 2-Propanol and distilled water. The ratio of TTIP: Urea was 1:3 for all doped and co-doped samples and cobalt nitrate was taken in four different concentrations i.e. 0.5%, 1%, 2%, 6% and 7%. The samples were characterized by SEM, EDX, XRD, UV-Vis DRS and BET. From SEM analysis the information about the morphology and particle size of nanoparticles was obtained. EDX gave information about elemental composition of all the synthesized catalysts. XRD results confirmed the presence of anatase phase and tetragonal structure in all the synthesized catalysts. From UV-Vis DRS data, band gap was calculated by Tauc plot and BET analysis helped in the determination of surface area. Photodegradation of methyl orange was carried out by using undoped TiO2, N-TiO2 and N, Co-TiO2 nanoparticles. The photocatalytic activity of nitrogen, cobalt co-doped catalysts was higher than undoped and nitrogen doped TiO2. The best catalyst was than selected for the synthesis of nanocomposite with graphene oxide. Graphene oxide was synthesized by Hummers‟ method and nanocomposite was synthesized by hydrothermal method. The nanocomposites were synthesized in three different ratios of N, Co-TiO2: GO which were 1:1, 1:1.5 and 1:2. These nanocomposites were than used for photocatalytic degradation of methyl orange. Nanocomposite with 1:1.5 showed best results as compared to other two nanocomposites. Highest degradation efficiency was achieved with NC-2 that was 93%.