## 3 Results and Discussion
### Polarization Curves  
Anodic and cathodic polarization curves of mild steel in 1 M HCl medium at various concentrations of tested inhibitors at 308 K are shown in Figure 9. Corrosion data including corrosion potential (\(E_{corr}\)), corrosion current densities (\(I_{corr}\)), anodic Tafel slope (\(\beta_{\text{a}}\)), cathodic Tafel slope (\(\beta_{\text{c}}\)), and inhibition efficiency are listed in Table 5. The inhibition efficiency (\(E_{i}\%\)) was calculated from polarization measurements using Equation (11).  
\[E_{i}\%=\frac{I_{corr}^{0}-I_{corr}}{I_{corr}^{0}}\times 100 \tag{12}\]  
where \(I_{corr}\) and \(I_{corr}^{0}\) are, respectively, the inhibited and uninhibited current densities.  
Analyzing Figure 9 and Table 5, we saw a shift in the anodic and cathodic curves towards low current densities, which indicates that the two processes of hydrogen ion reduction and mild steel anodic dissolution are limited in the inhibited media [47]. The limitation of these two processes became more intense while AO and HERA concentrations increased. The inhibition efficiency of AO (87.878%) is greater than HERA's efficiency (82.913%). This outcome is entirely in line with our expectations. We assumed that when  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & **Concentration** & \(E_{corr}\) & \(\beta_{\text{c}}\) & \(\beta_{\text{a}}\) & \(I_{corr}\) & \(E\) (\%) \\  & **(g/L)** & **(mV)** & **(mV/Dec)** & **(mV/Dec)** & **(mA/cm\({}^{2}\))** & **(\(\Delta\)/cm\({}^{2}\))** & **\(E\) (\%)** \\ \hline
**Blank** & - & \(-454\) & \(-182.9\) & \(151.8\) & \(1.95\) & - \\ \hline \multirow{4}{*}{**AO**} & \(0.06\) & \(-452\) & \(-175.6\) & \(125.1\) & \(0.64\) & \(67.07\) \\  & \(0.12\) & \(-453.2\) & \(-228.9\) & \(128.3\) & \(0.58\) & \(70.60\) \\  & \(0.25\) & \(-462.8\) & \(-270.1\) & \(189\) & \(0.55\) & \(71.94\) \\  & \(0.5\) & \(-447.7\) & \(-225.2\) & \(134.9\) & \(0.47\) & \(76.03\) \\  & \(1\) & \(-454\) & \(-213.2\) & \(137.1\) & \(0.32\) & \(83.44\) \\  & \(2\) & \(-436\) & \(-189.6\) & \(93.5\) & \(0.24\) & \(\mathbf{87.88}\) \\ \hline \multirow{4}{*}{**HERA**} & \(0.06\) & \(-416.8\) & \(-193.3\) & \(102.1\) & \(0.55\) & \(72.01\) \\  & \(0.12\) & \(-437.2\) & \(-207.0\) & \(116.1\) & \(0.44\) & \(77.65\) \\ \cline{1-1}  & \(0.25\) & \(-435.7\) & \(-138.6\) & \(104.9\) & \(0.37\) & \(80.75\) \\ \cline{1-1}  & \(0.5\) & \(-439.2\) & \(-204.9\) & \(111.9\) & \(0.35\) & \(82.22\) \\ \cline{1-1}  & \(1\) & \(-438.6\) & \(-156.5\) & \(107.1\) & \(0.34\) & \(82.52\) \\ \cline{1-1}  & \(2\) & \(-443.3\) & \(-147.9\) & \(109.1\) & \(0.33\) & \(\mathbf{82.91}\) \\ \hline \hline \end{tabular}
\end{table}
Table 5: Potentiodynamic polarization descriptors of mild steel in 1 M HCl in presence and absence of AO and HERA.  
Figure 9: Polarization curves of mild steel in 1 M HCl in presence and absence of AO and HERA.  
using salt during the artisanal extraction of argon oil, that AO may result in an increase in chloride ions in the oil. These ions can be adsorbed on the mild steel surface, providing a protective coating and lowering corrosion rates. This result could potentially be owing to the presence of a complex mixture of organic compounds other than fatty acids, that the hexane used for extracting HERA could not dissolve and extract from the organ kernels. In their work on diamionaphthalene as a mild steel corrosion inhibitor, [PERSON] et al. proved the synergetic effect of chloride ions [48]. On the other hand, this finding was further supported by relatively more shifts in the values of \(\beta\)c as compared to the values of \(\beta_{\text{a}}\). Inspection of Figure 5 reveals that potentiodynamic polarization curves are parallel and similar in the absence and presence of different concentrations of the studied inhibitors indicating that these molecules inhibit metallic corrosion by blocking the active sites present over the metallic surface without changing the mechanism of mild steel corrosion [49].