Synergistic Effect of KI on Corrosion Inhibition of Mild Steel by Polynuclear Schiff Base in Sulphuric Acid

Table 4

Electrochemical Impedance parameters of MS specimens in 0.5 M H₂SO₄ at 30°C in the absence and presence of inhibitor (a) and inhibitor + 0.2 mM KI (b).

(a)

𝐶; (mM)	𝑅ct; (Ω·cm^2)	𝐶dl; (𝜇F cm^−2)	𝜂EIS%
0	8.9	135	—
0.2	10.9	103	18.35
0.4	17.7	95.1	49.72
0.6	21.1	94	57.82
0.8	28.8	87	69.10
1.0	38.6	75.8	76.94

(b)

𝐶; (mM)	𝑅ct; (Ω·cm^2)	𝐶dl; (𝜇F cm^−2)	𝜂EIS%
0	8.9	135	—
0.2 + KI	91	99.9	90.22
0.4 + KI	102	93.7	91.27
0.6 + KI	151	91.3	94.11
0.8 + KI	198	79.7	95.51
1.0 + KI	251	65.1	96.45