Using a Thermodynamic Model of Adsorption to Describe the Behavior of Salts of Modified Humic Acid in Surface Layers

A mathematical model of polymolecular adsorption developed for protein solutions at liquid–gas interfaces (V.B. Fainerman, R. Miller, et al.) is used to describe experimental concentration dependences of the change in the equilibrium surface tension and viscoelastic modulus of aqueous solutions of salts of modified humic acids and hymatomelanic acids. It is shown that experimental data are in satisfactory agreement with theoretical estimates. The polymolecular adsorption model of natural polyelectrolytes for solutions of salts of modified humic acids is used to identify correspondence between experimental data and theoretical calculations for bimolecular adsorption, and for the trimolecular adsorption of macromolecules from solutions of salts of hymatomelanic acids at interfaces with air.