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 was synthesized to investigate its interaction with UO2+2. This substance 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 determination of carboxylic groups, IR spectroscopy and capillary electrophoresis. The interaction of this synthetic HA with UO2+2 was compared to the natural HA from Fluka by extended X-ray absorption fine structure (EXAFS) spectroscopy. Time-resolved laser-induced fluorescence spectroscopy (TRLFS) was used for characterizing the fluorescence behavior of the HA's. These investigations reveal structural and functional similarities between the synthetic HA and the natural HA. (orig.)