Effect of Ca²⁺ and Zn²⁺ ions on the adsorption and inhibitory properties of polyhexamethyleneguanidine derivatives

The introduction of Ca²⁺ and Zn²⁺ ions into solutions containing polyhexamethyleneguanidine derivatives leads to the increase of their inhibitory effect in the steel corrosion in neutral medium. It was shown, that inhibition effect has adsorption nature and linearly depends on the degree of filling of the electrode with an inhibitor. It was established, that in the consequences of complexation of modified polyhexamethyleneguanidines with Ca²⁺ and Zn²⁺ cations the structure, charge and hydrophilic-lipophilic balance of macromolecules are changing which lead to a change in the free energy of interaction of the macroparticles with the solvent and the growth of “displacement” on a free surface. In the high media hardness the most effective inhibitor is a zinc complex of carboxylated polihexamethyleneguanidine.