## 3 Results and Discussion

Table 3: Registered time of first corrosion attacks during the salt spray testing (\(\tau_{\rm corr}\), hours). Figure 2: Brass samples before (**A**) and after salt spray corrosion testing without an inhibitor (**B**), and in the presence of 3-mercapobutyl-5-amino-1\(H\)-1,2,4-triazole at concentrations of 1 (**C**), 5 (**D**), 10 mM (**E**). The electrochemical impedance spectroscopy also proves that a protective film forms on brass in neutral chloride solutions with 3-mercaptoethanolalkyl-5-amino-1\(H\)-1,2,4-triazoleoles. Figure 4 presents Nyquist diagrams obtained for the chloride-borate solution with (Figure 4a) and without the A, B, and C inhibitors with concentrations of \(C_{\text{inh}}=0.01\)-\(1.00\) mM (Figure 4b-d). The hodographs are presented as imperfect semi-circumferences, the imperfection being usually accounted for by the impedance frequency dispersion and the geometric and/or energetic inhomogeneity of the electrode's surface. We can see that when the organic additives are added to the neutral solution, or when \(C_{\text{inh}}\) increases, the shape of the impedance diagram does not change, but the radius of the semi-circumference increases significantly. The regression analysis of the impedance spectroscopy data was used to determine the most probable equivalent circuit simulation the processes at the brass/solution interface (Figure 5). Table 5 presents the values of the following circuit elements: \(R_{\Omega}\) (ohmic resistance of the solution), \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Polarization Mode**} & \multicolumn{4}{c}{**Element**} \\ \cline{2-5}  & **Cu** & **Zn** & **O** & **Cu/Zn** \\ \hline No polarization & 61.16 & 38.84 & 0.00 & 61/39 \\ After polarization in borate buffer + 10 mM NaCl & 59.04 & 37.51 & 3.45 & 61/39 \\ After polarization in borate buffer + 10 mM NaCl + 1.00 mM & 57.13 & 35.47 & 7.39 & 62/38 \\ of 3-mercapto(3-methylbutyl)-5-amino-1\(H\)-1,2,4-triazole & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Elemental surface composition (at. %) of the brass electrode. Figure 3: SEM micrographs of \(\alpha\)-brass surface (**a**) before polarization, (**b**) after polarization in borate buffer (pH 7.4) + 10 mM NaCl, (**c**) after polarization in borate buffer (pH 7.4) + 10 mM NaCl + 1.00 mM of 3-mercapto(3-methylbutyl)-5-amino-1\(H\)-1,2,4-triazole (structure B). \(C_{\rm DL}\) (double-layer capacitance), \(R_{\rm P}\) (polarization resistance of the electrochemical reaction), and \(BW\) (Warburg impedance). Figure 4: The Nyquist diagrams of brass in borate buffer (pH 7.4) + 10 mM NaCl without an inhibitor (**a**), in the presence of 3-mercaptoethanolpropyl-5-amino-1\(H\)-1,2,4-triazoleole (**b**), 3-mercaptoethanolbutyl-5-amino-1\(H\)-1,2,4-triazoleole (**c**) and 3-mercaptoethanol(3-methylbutyl)-5-amino-1\(H\)-1,2,4-triazoleole (**d**) at concentrations of 0.01 (1), 0.10 (2), and 1.00 mM (3). Figure 5: The electric equivalent circuit model used to fit the electrochemical impedance spectroscopy response (\(R_{\Omega}\)-direct-current resistance, \(C_{\rm DL}\)-double-layer capacitance, \(R_{\rm P}\)-polarization resistance of the electrochemical reaction, \(BW\)-Warburg impedance). \(R_{\text{P}}\) is significantly higher in solutions with an organic additive and increases when \(C_{\text{inh}}\) is higher, while \(C_{\text{DL}}\) noticeably decreases. We can thus say that the changes in the hodograph are most probably caused by the decrease in the double-layer capacitance resulting from the adsorption of the inhibitor molecules at the brass/solution interface, on the one hand, and the increase in the polarization resistance resulting from the formation of a protective film on the brass surface, on the other. Further evidence of the formation of the film is that the Warburg impedance grows rapidly in the presence of the inhibitor (Table 5).