Annealing effect on synthesized ZnS/TiO2 nanocomposite for treatment of industrial wastewater

Low cost and easy sol-gel process was adopted to synthesize ZnS/TiO2 nanocomposites and annealed at different temperatures 100, 450, 750 and 1050 degrees C. X-ray diffraction (XRD) analysis revealed that crystallinity increased gradually with increasing temperature and TiO2 phase transformed from bulk to anatase at 450 degrees C, anatase to rutile at 750 degrees C and 1050 degrees C respectively. It was observed from obtained UV-visible spectra that absorption increased with temperatures and reduction in bandgap energies from 3.31 to 3.0 eV. Fourier transform infrared (FTIR) spectroscopy confirmed the presence of Ti-Obonding correspond to 450-500 cm(-1) and phase formation was confirmed by Raman spectroscopy. Filed emission scanning electron microscopy (FESEM) images portrayed the presence of flower flakes like particles (100 degrees C), nanorods (450 degrees C) and agglomerations of nanocomposites were seen with higher temperatures. Photocatalytic measurements of nanocomposite were considered by irradiating methylene blue (MB) dye solution under visible light. It was noted that nanocomposite at low temperature bleaches out methylene blue more than higher temperature.