A COMPARISON OF NATURAL HUMIC ACIDS WITH SYNTHETIC HUMIC-ACID MODEL SUBSTANCES - CHARACTERIZATION AND INTERACTION WITH URANIUM(VI)

An artificial humic acid (HA) from xylose, phenylalanine and glycine w as synthesized to investigate its interaction with UO22+. This substan ce was characterized by different analytical methods, e.g., elemental analysis, radiometric determination of functional groups (carboxylic, phenolic OH and ester groups), calcium acetate exchange for the determ ination of carboxylic groups, IR spectroscopy and capillary electropho resis. The interaction of this synthetic HA with UO22+ was compared to the natural HA from Fluka by extended X-ray absorption fine structure (EXAFS) spectroscopy. Time-resolved laser-induced fluorescence spectr oscopy (TRLFS) was used for characterizing the fluorescence behavior o f the HA's. These investigations reveal structural and functional simi larities between the synthetic HA and the natural HA.