Hassle free synthesis of nanodimensional Ni, Cu and Zn sulfides for spectral sensing of Hg, Cd and Pb: A comparative study.

A simple room temperature synthesis method of Ni, Cu and Zn sulfide nanoparticles (NPs) in aqueous medium is reported here. The NPs stabilized in aqueous medium by the citrate ions were characterized by UV-vis, ζ potentials, TEM and Raman spectroscopic techniques. The solid NPs could be isolated from the aqueous medium when allowed to stand for a prolonged time (~20h). The solids were also characterized by IR and powder X-ray analysis. The nanoparticles were further used for the development of facile optical sensing and detection of heavy metal ions at trace scale. Alterations in the absorption spectra of the generated NPs were indicative of their interactions with heavy metal ions. Raman spectral measurements further validate the detection technique. It is found that out of the three synthesized nanoparticles, nickel sulfide NP is a specific sensor for mercury ions whereas zinc sulfide and copper sulfide NPs act as sensors for Hg2+ , Cd2+ and Pb2+ .