engleski

Conformations of humic substances and their sorption to mineral surfaces

Disertation using Atomic Force Microscopy (AFM) proved to be in agreement with more estabilished techniques of SEM/TEM imaging, but with the benefit of revealing small molecular conformations that remained invisible to SEM/TEM. The second advantage of AFM is that it does not require elaborate sample preparation as previous techniques did, thus, eliminating problems with structures that are result of sample preparation. Briefly, this research showed that the most important factor controlling different conformations observed is fulvic acid concentration. Based on surface pressure and viscosity measurements, research concluded that concentration is the first controlling factor of NOM configuration, yet, at low NOM concentration, pH and ionic strength become important as well. Since average concentration of NOM in natural system is usually relatively low, testing of pH and ionic strength is of utmost importance. Specific hypothesis raised by mentioned studies can be summarized as follows: Conformations of NOM compounds are primarily dominated by their concentration, however, other factors may contribute to its conformations, such as pH, ionic strength and presence of different cations. Variations can also be caused by different environments of origin and source material.

Atomic Force Microscopy; humic substances; sorption; mineral surface;

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