Specific Features of the Formation of Adsorption Layers from Products of Mechanochemical Modification of Humic Acids at a Liquid–Gas Interface

Abstract

Ethoxy- and aminoderivatives of natural polymers, humic acids, have been obtained via mechanochemical synthesis in a vibrational apparatus. The structure and physicochemical properties of their macromolecules have been studied by IR and UV spectroscopies. The average molecular mass of the products has been determined. The pendant drop shape and oscillating pendant drop methods have been employed to study the tensiometric and dilatational rheological characteristics of the surface layers formed at the interfaces between air and solutions of the modified derivatives of humic acids. It has been found that the formation of the adsorption layers of humic acid salts agrees with the protein adsorption model, which takes into account the possible existence of n states of macromolecules and their ability to aggregation in the surface layers when using the relations of the model in a semiempirical form. It has been shown that the viscoelasticity moduli of the surface layers of the ethoxylated derivatives of humic acids are increased relative to that of their unmodified form. Aminoderivatives of humic acids exhibit a higher stability in an acidic medium due to the presence of amino groups.