Photocatalytic degradation of dyes in water by analytical reagent grades ZnO, TiO<sub>2</sub> and SnO<sub>2</sub>: a comparative study

Abstract

Abstract. In this study, we evaluated the photocatalytic activities of analytical reagent (AR) grade ZnO, TiO2, and SnO2 to identify a low-cost photocatalyst for dye degradation. The obtained samples of ZnO, TiO2, and SnO2 were characterised by X-ray diffractogram (XRD), scanning electron microscope imaging, and UV-VIS diffuse reflectance spectroscopy. The decolourisation of three structurally diverse dyes, namely crystal violet, basic blue, and methyl red under solar irradiation, was used to evaluate the photocatalytic activities of three metal oxides. The photocatalytic activities of the received three metal oxides were tested with the photocatalytic degradation of dyes and compared with Degussa P-25. Dye solutions with each metal oxide at initial pH 9 were subjected to irradiation under sunlight and monitored for up to the stage of complete decolourisation. The results indicate that ZnO exhibited the highest photocatalytic activity as compared to TiO2 and SnO2 as well as that of Degussa P-25 (TiO2). The photocatalytic dye decolourisation rates with ZnO were 1.14–1.35, 1.70–3.1, and 4–8.5 times higher than those of the Degussa P-25, TiO2, and SnO2, respectively. The percentage COD removal was studied for ZnO and partial removal was observed at the decolourisation stage. To enhance photocatalytic activity of AR grade ZnO, it was loaded with Ag metal and about 20 % enhancement in the activity was observed.

Study of TiO2, SnO2 and nanocomposites TiO2:SnO2 thin films prepared by sol-gel method: Successful elaboration of variable–refractive index systems

“…TiO 2 and SnO 2 oxides have several advantageous properties such as availability, good thermal stability, low cost, easy to elaboration, good acid resistance, high band gap compared to traditional semi-conductors (3-4 eV) [1,2] and excellent optical quality. These properties make them attractive materials for several applications such as antireflective coating, optical filter, planar waveguides and solar cells [3][4][5][6][7][8][9].…”

“…Owing to the numerous published papers on pure transparent conducting oxide (TCO) thin films [2,10], it is necessary to develop other works which could be devoted to change and enhance the properties of these films using new different approaches. The formation of multi-oxide systems or nanocomposites is one of the most important approaches despite the few works devoted to this domain.…”

Photocatalytic Degradation of Monoazo Dye in Ethanol using Zinc Oxide in Ultra-Violet Radiation

“…Photocatalytic degradation of different organic pollutants was studied by other researchers and similar results were observed in which ZnO is the best photocatalyst in comparison with TiO2. For instance, the percentage of reactive Red 15 dye removal was 87 % and 90.5 % using TiO2 and ZnO, respectively [24][25][26].…”

Characterization of ZnO and TiO2 Nanopowders and their Application for Photocatalytic Water Treatment

“…ZnO has a higher quantum efficiency than TiO 2 [37]. The results of the photocatalytic activities give indirect evidence that ZnO may have ability to absorb a larger fraction of photon energy more efficiently than TiO 2 [38].…”