Fluorescent light induced Cr(VI) reduction by citrate in the presence of TiO2 and ferric ions

Utilization of inorganic reducing agents, such as Fe(II) and sulfide for Cr(VI) reduction would result in an increase in solid waste production and subsequent treatment cost. Rapid decrease in Cr(VI) concentrations and less solid by-products are valuable in the remediation of Cr(VI) contamination. The enhancement of Cr(VI) reduction by organic compounds with activated surfaces allows us not only efficient uses of natural materials but also decrease of processing products. The experiments of this work were all conducted under the light in visible wavelength region. Titanium dioxides (TiO2) could accelerate Cr(VI) reduction by citrate; however, illumination was necessary to initiate the redox reaction. Although Fe(III) did not show any capability of reducing Cr(VI), it could increase the removal of Cr(VI) by TiO2 in the presence of citrate and fluorescent light. When develop remediation techniques for Cr(VI) contamination, natural sunlight or a cheaper light source (i.e., fluorescent light) can be used, instead of UV light which is often used in the current techniques of treatments of soil and water contamination. (C) 2004 Elsevier B.V. All rights reserved.