Interaction of colloidal soil particles, humic substances and cationic detergents studied by X-ray microscopy

Abstract

The interaction of soil colloids with humic substances and cationic detergents has been studied by X-ray microscopy. The major advantages of X-ray microscopy for these studies are the much higher resolution than achievable with light microscopy and the ability to image colloidal structures directly in aqueous media. Of particular interest was, how the coagulation force of cationic detergents will change the structure formed by the soil colloids when humic substances are present. The humic substances form a network-like structure around the soil colloids, thus increasing tremendously the surface available for chemical and physical reactions. Therefore, much more cationic detergent was necessary to introduce a coagulation of the structures formed by the soil colloids. In addition, humic substances and cationic detergents coagulate forming sphere shaped structures, where size, density and state of aggregation is a function of the concentration of the detergents. X-ray microscopic images give evidence for these results.