Reduction of Hexavalent Chromium Using L-Cysteine Capped Nickel Nanocatalysts

The aim of this study was to reduce the highly toxic hexavalent chromium Cr(VI) into less toxic chromium Cr(III) species by using nickel nanoparticles (Ni NPs) as catalysts in order to provide safety to the aqueous environment. In the first phase Ni NPs were synthesized in ethylene glycol and capped with l-cysteine by a modified microwave irradiation method using NaOH as the accelerator. The formed Ni NPs were characterized by various techniques such as UV-Visible spectroscopy, Fourier Transform Infra-red (FTIR) spectroscopy and Scanning Electron Microscopy (SEM). In the second phase the formed Ni NPs were immobilized on glass surfaces and employed as catalyst for the reduction of Cr(VI) ions. According to observations, 99% reduction of Cr(VI) ions was achieved in the presence of 0.5 mg of Ni NPs catalyst in just five minutes as compared to nickel powder that showed only 16% reduction in 15 minutes. The study has a great impact on the aqueous pollution control of Cr(VI) especially caused by the discharge of waste water from several industries utilizing Cr(VI) containing salt as one of the essential gradients.