Table 2. EIS Parameters for the Corrosion of Low Carbon Steel in 1.0 M HCl with Different Concentrations of Inhibitors.

compounds	CM	fmax (Hz)	Cdl (μF cm–2)	CPE (μΩ sn cm–2)	n	Rs (Ω cm2)	Rct (Ω cm2)	H (%)
HCl	1.0	8.13	29.14	64.62	0.80	3.52	125
DPTU	2 × 10–4	4.52	6.56	17.85	0.70	2.28	1778	93.0
	10–4	3.16	7.65	20.44	0.67	2.67	1461	91.4
	5 × 10–5	2.05	9.10	23.07	0.64	2.44	1074	88.4
	10–5	1.18	11.47	25.45	0.60	2.41	791	84.2
PPTU	2 × 10–4	2.21	3.91	9.59	0.66	2.31	3297	96.2
	10–4	1.91	4.07	11.33	0.59	2.66	3034	95.9
	5 × 10–5	4.54	4.53	15.46	0.63	2.46	2028	93.8
	10–5	5.37	5.87	20.54	0.64	2.49	1678	92.6