Surface-active substance monolayer stability after its formation

The effect of different concentrations of K+, Na+, Ca2+, Ni2+, Al3+ and Fe3+ ions on surface-active substance monolayer stability has been studied using molecular mechanics method. For numerical calculations, energy potential Amber was used. Arachidic acid was chosen as a surface-active substance for monolayer formation because it is insoluble in water at normal conditions. Energy stability values representing system stability was calculated for different ion concentrations. It is established that the most stable system is formed by trivalent metal ions and that system stability decreases together with ionic charge. For each type of ions, a concentration value corresponding to most optimal stability was found with further increase of ion concentration leading to decrease of stability.