Study interaction between humic acids and metal ions using fluorescence quenching approach

The interaction of humic acids (HA) isolated from oxidized and brown coals with copper, nickel, and cadmium ions is investigated. The complexation constant of HA with heavy metal ions is determined using the fluorescence quenching method. It is shown that preliminary mechanic activation of humic-containing substances increases the binding coefficients of HA with copper and nickel ions in 1.5 to 3.5 times, as compared to cadmium ions, for which the values of the fluorescence quenching constant КSV decrease. This is due not only to structural changes in HA after the mechanic activation, but also to the nature of metal ions