Natural sunlight assisted photocatalytic degradation of methylene blue by spherical zinc oxide nanoparticles prepared by facile chemical co-precipitation method

A facile chemical co-precipitation method was employed to prepare spherical zinc oxide nanoparticles (S-ZnO NPs) and characterized by UV-vis diffuse reflectance spectrophotometer (UV-vis DRS), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) and energy dispersive spectrometer (EDS). UV-vis DRS of S-ZnO NPs disclosed strong absorbance in wavelength range from 200 nm-450 nm with characteristic absorption band edge of 394 nm. XRD pattern of S-ZnO NPs displayed diffraction peaks that confirm formation of hexagonal wurtzite structured ZnO. High intense and sharp diffraction peaks suggested high crystallinity of S-ZnO NPs. FESEM and HRTEM images of S-ZnO NPs exhibited spherical shape with diameter of 25 nm-200 nm. EDS spectrum of S-ZnO NPs revealed presence of Zn and 0 atoms and their purity. Photocatalyst degradation of methylene blue (MB) by S-ZnO NPs under natural sunlight showed 61.45 % removal of MB at 45 min. Investigation on reaction kinetics showed that photocatalytic decomposition of MB was in harmony with pseudo first-order reaction kinetics with reaction rate constant of 0.0228 / min.