Changes in the Physicochemical Characteristics of Humic Acids in a Hydrodynamic Rotor-Pulsation Apparatus

The work presents research results of the change comparison of brown coals and the study of the physicochemical properties of humic substances obtained from brown coals of the Karazhyra, Ekibastuz, and Kyzyl-Kiya deposits after hydrodynamic treatment in a rotary-pulsation apparatus. It is shown that the hydromechanical effect on humic acids leads to a change in their composition, accompanied by a decrease in the degree of aromaticity and an increase in the content of oxygen-containing fragments. Mechanical treatment of brown coals under oxidizing conditions maximizes the efficiency of extraction of water-soluble components and humic acids. The structural parameters and functional composition of humic acid molecules during the treatment of brown coals under oxidation-reduction conditions change depending on the conditions. The elemental and functional composition (using IR spectroscopy and potentiometry) of humic substances in brown coals and their molecular weight distribution using size-exclusion chromatography were studied. The influence of the content of metal-binding centers, dispersity, and ash content of humic substances was studied before and after treatment. At a temperature of 70 ºC a rotation time of 10 s, 98.7% of humic acids passes into the solution, which is the best indicator.