Table 2.

EIS parameters and corrosion inhibition efficiencies obtained from fitting impedance spectra of C-steel in 0.5 M HCl at different concentrations of AEO7 at 20, 30, 40 and 50 °C using the electrical equivalent circuit shown in Fig. 4.

T (°C)	Cinh µmol L−1	Rct, Ω cm2	CPE			$\theta$	Corrosion IE%
			Y0 µsn ohm−1 cm−2	Cdl, µF	n
20	Blank	43.1	257.0	119.7	0.855	—	—
	20	128.2	211.7	82.57	0.793	0.664	66.4
	30	169.8	194.5	76.85	0.786	0.746	74.6
	35	253.0	161.4	69.31	0.791	0.830	83.0
	40	341.6	105.95	59.49	0.852	0.874	87.4
30	Blank	30.8	381.8	218.7	0.889	—	—
	20	90.42	314.1	202.2	0.890	0.660	66.0
	30	114.2	260.4	156.8	0.874	0.730	73.0
	35	164.5	236.8	103.6	0.797	0.813	81.23
	40	211.5	149.2	64.25	0.804	0.854	85.4
40	Blank	24.27	425.0	252.7	0.898	—	—
	20	64.8	405.7	231.0	0.866	0.625	62.5
	30	89.0	390.3	185.7	0.819	0.727	72.7
	35	112.2	377.0	141.9	0.764	0.786	78.6
	40	145.8	331.4	124.6	0.756	0.833	83.3
50	Blank	18.5	606.5	295.6	0.862	—	—
	20	49.27	554.2	254.1	0.822	0.622	62.2
	30	59.32	543.7	217.4	0.789	0.688	68.8
	35	69.72	515.7	187.7	0.890	0.734	73.4
	40	90.42	492.8	155.0	0.729	0.795	79.5