Tensiometric and Rheological Characteristics of Fractions of Humic and Hymatomelanic Acids

Resumo

The Du Nouy ring detachment and pendant drop methods have been employed to study the tensiometric (dynamic and equilibrium surface tensions) and surface rheological (viscoelasticity modulus and phase angle) characteristics of aqueous solutions of fractions of humic and hymatomelanic acids at a solution–air interface. It has been found that the fraction of low-molecular-weight hymatomelanic acids has high surface activity, while its surface layers are characterized by high viscoelasticity and storage elastisity moduli. The experimental dependences of the equilibrium surface tension and viscoelasticity modulus on the concentration of hymatomelanic acid salt solutions are adequately described in terms of the model of real two-dimensional solutions for polymolecular adsorption of polyelectrolytes.