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

Table 5

Values of the elements of equivalent circuit required for fitting the EIS for C38 steel immersed in the presence and absence of harmane at different temperatures.

	Temp (°C)	𝑅ct (Ω cm^2)	𝐴10^4 (Ω^−1 s^𝑛 cm^−2)	𝑛	𝐶dl (𝜇F cm^−2)	𝐿 (H cm^−2)	𝑅𝐿 (Ω cm^2)	IE (%)	𝜃
	25	49 ± 0.02	9.5 ± 0.73	0.853 ± 0.014	546	—	—	—	—
Blank	35	17 ± 0.64	20.5 ± 4.21	0.795 ± 0.421	863	18 ± 1.87	6 ± 1.26	—	—
	45	12 ± 0.94	43.5 ± 3.56	0.745 ± 0.362	1583	15 ± 2.35	3 ± 0.87	—	—
	55	3 ± 0.96	72.8 ± 5.64	0.735 ± 0.093	1834	10 ± 8.54	2 ± 1.25	—	—
0.2 mM	25	181 ± 0.10	4.82 ± 0.19	0.866 ± 0.042	330	—	—	73	0.7293
	35	73 ± 0.61	6.92 ± 0.44	0.816 ± 0.501	353	—	—	71	0.7123
	45	50 ± 1.23	9.73 ± 0.27	0.805 ± 0.062	468	25 ± 8.41	8 ± 3.02	70	0.7000
	55	16 ± 0.81	19.5 ± 4.03	0.719 ± 0.501	503	11 ± 0.34	3 ± 0.8	69	0.6875
0.4 mM	25	321 ± 0.97	3.71 ± 0.37	0.870 ± 0.036	270	—	—	85	0.8474
	35	129 ± 0.65	5.29 ± 0.09	0.804 ± 0.074	275	—	—	84	0.8372
	45	82 ± 1.54	7.95 ± 1.02	0.784 ± 0.128	375	25 ± 1.74	9 ± 1.5	82	0.8171
	55	21 ± 2.31	10.31 ± 2.13	0.824 ± 0.054	455	21 ± 0.58	4 ± 1.3	76	0.7619
0.8 mM	25	537 ± 0.17	2.52 ± 0.27	0.873 ± 0.051	188	—	—	91	0.9088
	35	218 ± 0.56	3.96 ± 0.72	0.795 ± 0.104	211	—	—	90	0.9037
	45	136 ± 1.53	4.37 ± 0.73	0.811 ± 0.091	226	—	—	89	0.8897
	55	27 ± 1.20	8.64 ± 2.03	0.780 ± 0.035	299	5 ± 0.12	2 ± 0.76	81	0.8148
1.2 mM	25	735 ± 0.68	1.92 ± 0.12	0.883 ± 0.036	148	—	—	93	0.9333
	35	293 ± 0.54	3.28 ± 0.27	0.814 ± 0.037	192	—	—	93	0.9283
	45	182 ± 0.53	4.33 ± 0.07	0.826 ± 0.051	254	—	—	92	0.9176
	55	32 ± 0.66	7.36 ± 1.91	0.783 ± 0.102	260	11 ± 1.54	5 ± 0.8	84	0.8438