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

Table 2

Electrode kinetic parameters for corrosion of mild steel in 1 M HCl with various concentrations of 4-hydroxy coumarin in the presence and absence of 10⁻³ M KI.

[Inh] M	[KI] M	−𝐸corr mV	𝐼corr mA/cm^2	𝑏𝑎 mV/dec	𝑏𝑐 mV/dec	%IE	𝑆
Blank	—	506	11.12	206	166	—	—
—	10^−3	503	8.39	199	162	24.55	—
0.001	—	509	10.04	230	180	9.73	1.126
—	10^−3	496	6.72	152	130	39.52
0.007	—	483	6.54	199	143	41.19	1.197
—	10^−3	516	4.12	149	152	62.94
0.009	—	492	6.40	180	143	43.17	1.167
—	10^−3	496	4.08	163	129	63.27
0.010	—	495	4.41	174	154	60.81	1.128
—	10^−3	509	2.96	126	111	73.39