The Analysis of the Quenching Efficiency of Humic Acid Fluorescence by Cadmium and Copper Ions

Abstract

In conditions of monochromatic excitation ( λ exc =337.1), the spectral dependence of the efficiency of fluorescence quenching α λ of humic acids samples by Cd 2+ and Cu 2+ ions was studied. The difference of α λ dependencies for these ions was established. In the spectral range 350 - 650 nm, changes of the α λ for Cd 2+ ion are markedly different from the magnitude for changes α λ , which occur for ion Cu 2+ . The interpretation of mismatch dependences obtained α λ ions Cd 2+ and Cu 2+ is carried out within the concept of the availability of different sites, due to the difference in ionic radii (0.108 nm and 0.08 nm for Cd 2+ and Cu 2+ , respectively).