The Formation of Passive Films on Magnesium in Alkaline Solutions and Adsorption of Anions of Organic Acids on Them

The growth of oxide films on the surface of magnesium in 5M NaOH and a borate buffer solution with pH of 11.2 is studied. The thickness of the oxide film on the surface of magnesium reaches about 70 nm in an 5M solution of NaOH and about 50 nm in a borate buffer solution with pH of 11.2 over 120 min. Isotherms of adsorption of 5-chlorobenzotriazole and dioctyl phosphate in a borate buffer solution with pH of 11.2 are obtained. The free energy of adsorption of these compounds is the same, 50.2 kJ/mol.