Abstract

In recent years, photocatalytic oxidation using semiconductor nanoparticles (NPs) has gained global attention as a method for
wastewater treatment. In view of this, the present work reports the results of the investigations on the use of cobalt oxide (CoO)
NPs on the photocatalytic degradation of methyl violet (MV). The CoO NPs were synthesized by a hydrothermal route and were
then characterized using Fourier-transform infrared, ultraviolet diffuse reflectance spectroscopy, ultraviolet–visible, Raman,
X-ray diffraction, vibrating-sample magnetometer, transmission electron microscopy, scanning electron microscope, and Energy
dispersive X-ray spectroscopy (EDAX) techniques. The NPs were found to be spherical and in size range of 3–5 nm. The NPs
were also subject to calcination in the temperature range of 150–350°C. The temperature of calcination seemed to influence the
surface composition of CoO. Both calcined and uncalcined CoO NPs were then subject to studies on the degradation of MV. The
CoO 350 NPs exhibited the best photocatalytic degradation efficiency of 73% for the degradation of MV.