Table 2.
Impedance parameters for Harmal extract on C-steel in 0.25 M H2SO4 medium by fitting the equivalent circuit model B.
| Harmal Extract ppm |
RS Ω cm2 |
Rf Ω cm2 |
ZCPEf µΩ−1s n cm−2 |
nf |
Rct Ω cm2 |
ZCPE µΩ−1s n cm−2 |
n | Rf + Rct |
Cdl μF/cm2 |
θ | IE% |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 | 3.83 | 5.98 | 359.06 | 1.00 | 1.37 ± 1 | 1150.79 | 0.800 | 7.35 | 229.01 | - | - |
| 20.79 | 4.29 | 10.00 | 292.22 | 0.906 | - | - | 0.145 | - | - | - | - |
| 41.49 | 3.21 | 3.10 | 49,090 | 0.409 | 11.31 ± 2 | 248.46 | 0.926 | 14.41 | 155.36 | 0.879 | 87.9 |
| 62.11 | 4.53 | 16.11 | 311.12 | 0.853 | 0.68 ± 1 | - | 1.00 | 16.78 | - | - | - |
| 82.65 | 4.23 | 15.81 | 274.72 | 0.795 | 25.71 ± 3 | 122.50 | 0.996 | 41.52 | 120.35 | 0.947 | 94.7 |
| 204.1 | 4.16 | 14.00 | 460.91 | 0.708 | 44.03 ± 4 | 108.33 | 0.937 | 58.03 | 76.15 | 0.969 | 96.9 |
| 283.4 | 4.21 | 7.96 | 1269.35 | 0.625 | 73.70 ± 8 | 98.33 | 0.904 | 81.65 | 58.58 | 0.981 | 98.1 |
| 625.0 | 4.00 | 23.94 | 268.35 | 0.727 | 75.61 ± 7 | 96.16 | 0.915 | 99.54 | 60.87 | 0.982 | 98.2 |
| 826.5 | 4.48 | 29.27 | 418.94 | 0.704 | 89.38 ± 9 | 94.89 | 0.916 | 118.65 | 61.27 | 0.985 | 98.5 |