Synthesis and Photocatalytic Activity of Ruthenium-Titania for Enhanced Decolorization of Malachite Green under Visible Light Illumination

The photodecolorization of malachite green (MG) dye was effectively done using Ruthenium-doped TiO2 photocatalysts under visible light illumination. X-ray diffraction analysis revealed that anatase and rutile peaks were both found in undoped TiO2 while only anatase peaks were present in Ru-doped TiO2 systems which were calcined at 500°C. The 0.008 Ru-TiO2 photocatalysts calcined at 300°C showed broader peaks compared to those calcined at 500°C. Further increase of calcination temperature to 700°C promotes the transformation of anatase to rutile peaks. The photocatalytic activity of TiO2 was found to increase with the addition of Ruthenium ions, from 20% for undoped TiO2 to 87% for 0.80 Ru-doped TiO2. The maximum photocatalytic removal of MG dye was achieved using 1.50 g∙L-1 of catalyst loading for 0.008 Ru-doped TiO2. The TiO2 photocatalysts prepared at a calcination temperature of 500°C showed higher photodecolorization efficiency compared to those calcined at 300°C and 700°C. Kinetic studies revealed that the photodecolorization of MG using Ru-doped TiO2 followed a first order kinetics.