Synergistic Effect of Iodide Ion and 4-Hydroxy Coumarin on the Corrosion Inhibition of Mild Steel in Hydrochloric Acid

Table 4

Values of 𝐼_corr and %IE for corrosion of mild steel in 1 M HCl with different concentrations of 4-hydroxy coumarin in absence and presence of 10⁻³ M KI obtained by Stern-Geary equation.

[Inh] M	[KI] M	𝐼corr mA/cm^2	%IE
Blank	—	2.55	—
—	10^−3	1.76	30.98
0.001	—	2.43	4.71
—	10^−3	1.01	60.39
0.007	—	1.20	52.94
—	10^−3	0.78	69.41
0.009	—	1.15	54.90
—	10^−3	0.71	72.16
0.010	—	0.95	62.75
—	10^−3	0.50	80.39