The effects of inorganic anions, organic compounds, and combinations of the two on corrosion of mild steel in various acids were determined. From corrosion rates of steel in acids the order of the degree of adsorption of anions was concluded to be I−>Br−>Cl−>SO4=>ClO4− The largest effects on corrosion mitigation were observed for I− and I− in combination with amines. The specificity of effects attributable to I− suggests a strong interaction with the steel surface possibly through chemisorption. The enhancement of inhibitor efficiency by I− is dependent on molecular structure of the inhibitor. The extent of synergism between I− and organic amines was observed to be in the order: octamethyleneimine> di‐n‐butylamine>n‐octylamine. Synergistic effects of anions and organic cations is greater than can be expected by a shift in the metal surface potential by anion adsorption and must be attributed in part to stabilization of the adsorbed anion layer by organic cations, possibly by covalent bonding.

The surface tension of air/ normalNaCl solution interfaces with applied electrostatic fields of up to 6700 v/cm was measured using a surface energy balance. The normalNaCl concentration was 0–3.5%. It was found that fields of either polarity lower the surface tension of all investigated solutions. Magnitude of the surface tension changes and dependence on direction of the field lead to the conclusion that the potential drop at air/water interfaces is smaller than previously thought, that the water dipole orientation is only slight, and that the hydrogen in the oriented water molecule is facing the air. The experiments point out that the effect of the field is predominantly on the sodium ion. It is shown that the difference in the energy for adsorption at the interface between cations and anions cannot be neglected. Calculations on the basis of a modified Gibbs equation on the assumption of a diffuse double layer at the interface leads to unreasonably high surface deficiencies. Neglecting the diffuse double layer and reckoning on the basis of an inner double layer only leads to values of the same order of magnitude as those calculated from the Gibbs equation alone.

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Electrostatic fields of up to 7000 volt/cm have been applied across air/solution interfaces by means of parallel-plate electrodes, and the resulting surface tension changes were obtained by measuring, through a balance linkage, the deflection of mica plates floating on the surface. Surface tension changes (always negative) of up to 0.5 dyne/cm have been observed in both distilled water and dilute sodium chloride solutions.

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