Enhanced photodegradation of methyl orange dye under UV irradiation using MoO3 and Ag doped TiO2 photocatalysts

Abstract

Titanium dioxide (TiO 2 ) semiconductor-based photocatalysts have been widely utilized in the last few decades for water treatment because of their higher photocatalytic performance. Recently, most researchers have focused on the improvement of TiO 2 semiconductors’ photocatalytic performance through doping and co-doping with different metals and nonmetals during synthesis. The current study was conducted to synthesize TiO 2 based photocatalysts, construct TiO 2 photocatalysts based immobilized borosilicate glass (BG) reactors and applied the reactors for methyl orange (MO) dye treatment under UV irradiation. Based on XRD results, the dominant phase was anatase in all the photocatalysts. The largest amount anatase phase (82.43%) of Ag/MoO 3 /TiO 2 photocatalyst in comparison to TiO 2 (70.44%), MoO 3 /TiO 2 (74.18%) and Ag/TiO 2 (80.59%) photocatalysts were observed. The photocatalytic degradation of 10 ppm MO dye was found 59.5%, 63.1%, 70.6% and 75.8%, for TiO 2 , MoO 3 /TiO 2 , Ag/TiO 2 , and Ag/MoO 3 /TiO 2 photocatalysts, respectively, for a particular dose of photocatalyst (0.12 g) immobilized on BG at pH (7.0) after 5.5 h of UV-irradiation. The efficiency of the photocatalyst (Ag/MoO 3 /TiO 2 ) was decreased with the increase of pH and initial dye concentrations. However, increasing photocatalyst and hydrogen peroxide doses in the BG reactor resulted in a better performance as expected. The first-order reaction rate constants were 0.003, 0.002, 0.003, and 0.004 min −1 for TiO 2 , MoO 3 /TiO 2 , Ag/TiO 2 , and Ag/MoO 3 /TiO 2 , respectively, for 0.12 g of photocatalyst dose. The outcomes suggest future possibilities of applying Ag/MoO 3 /TiO 2 nanocomposite in the treatment of textile wastewater under UV irradiation. • Ag/MoO 3 /TiO 2 nanocomposites were synthesized by the sol–gel method. • XRD analysis shows anatase phase with tetragonal structure of Ag/MoO 3 /TiO 2 . • 75.8% of MO dye was degraded using Ag/MoO 3 /TiO 2 under 5.5 h UV irradiation. • % removal increased from 62.6 to 96.5% with the decrease of pH from 11.0 to 3.0. • Dye removal was increased with the addition of H 2 O 2 .