Table 3 Corrosion parameters derived from Nyquist curves for st-37 in HCl solution in the absence, and presence of different concentrations of inhibitor based on bulk, and nano size, at 25 ± 1 °C.
C/ppm | Chi-square | RS/Ω cm2 | Rct/Ω cm2 | Cdl/μF cm-2 | θ | IE% |
|---|---|---|---|---|---|---|
(a) Dracocephalum/HCl 1.0 M | ||||||
Blank | 0.031 | 1.17 | 18 | 135 | – | – |
100 | 0.042 | 2.68 | 39 | 83 | 0.54 | 54 |
200 | 0.029 | 1.21 | 68 | 62 | 0.74 | 74 |
300 | 0.014 | 1.17 | 99 | 57 | 0.82 | 82 |
400 | 0.0082 | 1.21 | 203 | 37 | 0.91 | 91 |
500 | 0.012 | 1.13 | 145 | 40 | 0.88 | 88 |
(b) Dracocephalum (nano)/HCl 1.0 M | ||||||
50 | 0.029 | 1.44 | 65 | 50 | 0.72 | 72 |
75 | 0.014 | 1.24 | 89 | 36 | 0.80 | 80 |
100 | 0.036 | 1.08 | 154 | 65 | 0.88 | 88 |
125 | 0.24 | 1.75 | 123 | 35 | 0.85 | 85 |
