Corrosion Inhibition Effect of 4-Hydroxy-N′-[(E)-(1H-indole-2-ylmethylidene)] Benzohydrazide on Mild Steel in Hydrochloric Acid Solution

Table 1

Tafel polarization results for the corrosion of mild steel in 1 M HCl in the absence and presence of inhibitor at different temperatures.

Temp. (°C)	Conc. of HIBH (mM)	(mV/SCE)	(mV dec^−1)	(mV dec^−1)	(mA cm^−2)	CR (mmy^−1)	% IE
30	0		73.1	73.1	1.894	11.74	—
	0.01		65.0	73.8	0.534	3.31	71.7
	0.025		69.2	99.8	0.486	3.01	74.3
	0.05		68.9	112.3	0.374	2.45	80.2
	0.1		73.5	119.3	0.269	1.67	85.7
	0.2		78.2	113.4	0.240	1.49	87.3
	0.4		76.6	102.4	0.206	1.28	89.1
	0.6		73.2	102.7	0.183	1.13	90.3
	0.8		78.8	115.7	0.161	1.00	91.4
40	0		68.7	60.9	3.352	20.78	—
	0.01		71.2	79.4	0.780	4.83	76.7
	0.025		76.3	98.5	0.641	3.98	80.8
	0.05		75.5	100.1	0.572	3.55	82.9
	0.1		77.9	102.3	0.467	2.90	86.0
	0.2		75.5	109.0	0.402	2.49	87.9
	0.4		72.5	101.7	0.394	2.44	88.3
	0.6		71.4	103.2	0.360	2.23	89.2
	0.8		74.1	102.2	0.224	1.39	93.3
50	0		61.3	57.8	6.458	40.03	—
	0.01		55.9	78.2	1.417	8.80	78.0
	0.025		72.6	82.5	1.104	6.88	82.9
	0.05		70.5	95.4	0.994	6.14	84.6
	0.1		64.9	95.4	0.900	5.58	86.1
	0.2		71.8	98.1	0.720	4.47	88.8
	0.4		77.3	97.0	0.622	3.85	90.3
	0.6		78.0	105.8	0.567	3.52	91.2
	0.8		77.5	105.0	0.389	2.41	93.9
60	0		54.3	52.5	12.43	77.0	—
	0.01		53.4	66.9	2.650	16.4	78.6
	0.025		55.3	72.5	2.356	14.6	81.0
	0.05		59.0	83.6	1.850	11.4	85.1
	0.1		55.9	93.8	1.693	10.4	86.4
	0.2		58.4	94.8	1.310	8.20	89.4
	0.4		53.9	92.0	1.224	7.58	90.2
	0.6		67.9	93.7	1.081	6.74	91.3
	0.8		64.9	96.0	0.710	4.45	94.2