Humic acid binding of trivalent Tl and Cr studied by synchronous and time-resolved fluorescence
The complexation of thallium(III) and chromium(III) with groundwater humic acids (HA) was investigated at pH 4.5 and 5.5 using different fluorescence methods. These comprised both quenching measurements of the continuous and synchronous fluorescence of the HA ligand, and an ion competition method based on the time-resolved laser-induced fluorescence of HA-bound europium(III). Modelling of the experimental data using an electrostatic discrete site approach (Model V) yielded comparable values of intrinsic binding constants for each of the studied metal, independently of sample conditions (pH, metal: ligand ratio) and fluorescence method used. The results confirmed the validity of fluorescence techniques in the analysis of low concentration metal ion-HA interactions, and also indicated that, besides the aquo ion and the first hydroxo complex, other species may also bind to humic acids.
Bibliographic Reference: Article: Environmental Science and Technology
Record Number: 199711322 / Last updated on: 1997-10-16
Original language: en
Available languages: en