Table 3.
Impedance parameters for Harmal extract on C-steel in 0.25 M H2SO4 medium by fitting the equivalent circuit Model C.
| Harmal Extract ppm |
RS Ω cm2 |
Rf Ω cm2 |
ZCPEf µΩ−1s n cm−2 |
nf |
Rct Ω cm2 |
ZCPE µΩ−1 s n cm−2 |
n |
W mS s1/2 |
Cdl μF/cm2 |
θ | IE% |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 | 3.78 | 0.60 | 4207.3 | 1.00 | 6.82 ± 1 | 308.7 | 1.00 | 11.47 | 308.73 | - | - |
| 20.79 | 4.51 | 7.83 | 221.2 | 0.975 | 3.97 ± 1 | - | 0.358 | 8.858 | - | - | - |
| 41.49 | 3.24 | 10.38 | 234.3 | 0.946 | 3.80 ± 1 | - | 0.999 | 9.442 | - | - | - |
| 62.11 | 4.41 | 13.01 | 236.9 | 0.924 | 3.87 ± 1 | - | 0.969 | 8.784 | - | - | - |
| 82.65 | 4.11 | 24.63 | 140.0 | 1.00 | 16.91 ± 2 | 113.0 | 0.931 | 4.915 | 71.08 | 0.597 | 59.7 |
| 204.1 | 4.07 | 40.15 | 115.0 | 0.957 | 17.80 ± 2 | 214.8 | 0.828 | 3.623 | 67.59 | 0.617 | 61.7 |
| 283.4 | 4.09 | 58.11 | 115.4 | 0.944 | 23.27 ± 3 | 194.4 | 0.907 | 2.310 | 111.74 | 0.707 | 70.7 |
| 625.0 | 3.94 | 12.59 | 226.0 | 0.786 | 86.87 ± 8 | 82.6 | 0.916 | 4.479 | 52.52 | 0.922 | 92.2 |
| 826.5 | 4.44 | 24.76 | 389.3 | 0.731 | 93.75 ± 9 | 89.2 | 0.925 | 7.970 | 60.53 | 0.927 | 92.7 |