Impact of wastewater strength and photocatalyst loading on decolourization of acid orange 7 by Co-doped TiO2

Heterogeneous photocatalysis has proved to be a successful method for the degradation of water pollutants. In this work, the photocatalytic decolourization of acid orange 7 was performed by cobalt-doped titanium dioxide (Co-doped TiO2). The Co-doped TiO2 was synthesized and characterized using X-ray diffraction, scanning electron microscopy, energy diffraction spectroscopy, UV-visible reflective dispersion spectroscopy and adsorption of nitrogen gas. The acid orange 7 was prepared as a synthetic textile wastewater at three initial concentrations (24, 34 and 44 mg/L) with three photocatalyst loadings (0.025 g, 0.050, 0.1 g/100 mL acid orange 7). Results show a plateauing behaviour with the effect of photocatalyst concentration on removal of acid orange 7. As the concentration increased of acid orange 7, an ideal photocatalytic loading was found that outperformed higher concentrations in regards to removal of acid orange 7. As such it was concluded that high photocatalyst concentrations are not synonymous with efficient water treatment.