Effect of Chloride Ion on the Relationship Between the Adsorption of Polar Organic Compounds on Nickel or Iron and the HSAB Principle

The hard and soft acids and bases principle (HSAB principle) was confirmed as being applicable to the adsorption behavior and corrosion inhibition effect of polar organic compounds on nickel and iron in solutions. Surface coverage of the compounds was calculated on the basis of the Frumkin adsorption. Since the softness of metal surface increased in the presence of Cl − , the compound classified as a soft base was readily adsorbed on the surface where Cl − was adsorbed.