PHYSICO-CHEMICAL PROPERTIRS OF HUMIC SUBSTANCES OF PEATS OF THE TULA REGION
The polydispersity of humic substances is proved by the method of exclusion chromatography. Four fractions differing in their molecular masses and relative content were obtained, regardless of the origin of humic substances. Low molecular weight fractions of humic substances are connected to each other through intermolecular interactions and hydrogen bonds into globular flexible-linear or elliptical structures, which are combined with each other, forming a “molecular ensemble” of macromolecules, which is confirmed by atomic force microscopy. The supramolecular structure of the molecules of humic substances of peats sorbed on hydrophilic mica was established and the sizes of single globular molecules of humic substances were determined. The values ??of the dissociation constants of acidic groups (-COOH and -OH) in the composition of humic substances were determined by the method of potentiometric titration. The relationship between the proportion of humic substances in the solution was determined at different pH values ??of the medium. It is proved that the solubility of humic substances is related to the chemical composition of the initial biomaterial, from which the humic substances are formed.