Changes in the Composition of Humic Acids with Mechanochemical Impact on Peat and Coal

Abstract

The analysis of the mechanochemical transformations of humic acids (HAs) in caustobioliths of different genesis (peat, brown coal, and oxidized coal) was carried out. It was found that the greatest changes in the peripheral carbohydrate fragments and the aromatic framework of a HA macromolecule occurred upon the mechanical activation of less transformed peats. The mechanochemical solid-phase alkaline hydrolysis of HAs was performed. Changes in the composition of HAs in the process of mechanical activation, which consist in an increase in the number of acid functional groups and in the degree of oxidation of aromatic and aliphatic fragments and in a decrease in the aromaticity of macromolecules, were detected.