Effect of pH on photocatalytic activity of capped ZnS nanoparticles.

In the present work, Zinc sulphide (ZnS) nanoparticles (NPs) capped with 2-Mercaptoethanol (2 ME) are synthesized via chemical precipitation method. Structural and morphological studies have been done using X Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) techniques. Band gap of as prepared NPs is determined using UV-Visible spectroscopy. Photoluminescence spectra of the synthesized NPs was recorded to study the emission properties. After optimizing the capping concentration, ZnS NPs were synthesized at different pH viz. 5.62 (natural pH), 8, 10, and 12 at optimized capping concentration. These nanoparticles were further used as a catalyst to degrade crystal violet dye. It has been observed that catalyst synthesized at pH 12 is able to degrade dye to a larger extent as compared to samples synthesized at pH 5.62, 8, and 10. Possible reason for this observation is discussed. Reusability of catalyst shows better results of dye degradation. UV curing studies of ZnS surface with different irradiation times (0-180 min) are done in this context.