Heavy-metal ion sensor using chitosan capped ZnS quantum dots

Presence of heavy metals like Zn, Cu, Cr, Cd, Ni and Hg in water is a major cause of water pollution. These metal ion pollutants can be detected using sophisticated and expensive instruments which takes considerable time for measurement. In contrast to the instrumentation, Quantum dots (QDs) like CdSe, CdS, CdTe, ZnS etc. can be used as instant and cheap heavy metal ion sensors. In this paper chitosan capped ZnS QDs are used to detect Zn2+ and Cu2+ ions present in water at different concentrations. A comparison of the optical properties of the colloidal suspension of ZnS before and after exposure to metal ions is carried out to assess the presence of metal ions.