Adsorption Properties and Inhibition of C38 Steel Corrosion in Hydrochloric Solution by Some Indole Derivates: Temperature Effect, Activation Energies, and Thermodynamics of Adsorption

Table 1

Corrosion parameters obtained from electrochemical measurements of C38 steel in 1 M HCl containing various concentrations of indole derivates at 25°C.

Inhibitor	Polarisation curves				EIS
	𝐸corr versus SCE (mV)	𝐼corr (𝜇A·cm^−2)	IE (%)	𝑅ct (Ω·cm^2)	𝐶dl (𝜇F·cm^−2)	IE (%)
1 M HCl	−529	284	—	49 ± 0.02	546
Norharmane
0.2 mM	−467	67	76	148 ± 0.91	183	67
0.4 mM	−476	61	79	238 ± 1.65	120	79
0.8 mM	−494	52	82	514 ± 1.18	55	90
1.2 mM	−455	28	90	641 ± 1.73	44	92
Harmane
0.2 mM	−476	65	77	181 ± 0.10	330	73
0.4 mM	−489	55	81	321 ± 0.97	270	85
0.8 mM	−479	34	88	537 ± 0.17	188	91
1.2 mM	−492	24	91	735 ± 0.68	148	93