Spectrofluorimetric Study of the Interaction of Gold (III) and Humic Acids under the Formation of Gold Nano-Particles

摘要

Humic acids are a complex mixture of partially "decomposed" and otherwise transformed organic materials from different sources. The chemistry of their formation is quite complex and still it is not completely understood. There are several subclasses of humic acids (tannins, lignins, fulvic acids, etc.). A substantial fraction of the mass of the humic acids is containing carboxylic acid functional groups which endow these molecules with the ability to chelate positively charged multivalent ions (Mg~(2+), Ca~(2+), Fe~(2+), Fe~(3+), Al~(3+) and most other "trace elements") [1]. The fluorescent structures are minor components in humic substances. Fluorescence spectroscopy is fast, relatively easy and powerful method to follow such fluorescence structures but also method for providing knowledge about the chemistry and nature of the interactions between gold (III) and HA. The reduction of Au(III) may be due to functional groups such as e.g. amino, hydroquinones and phenolics groups normally present on humic acids; functional groups which are recognized to be efficient reducing agents for gold cations [2].