## 3 Results  
### Electrochemistry  
Before conducting the electrodegradation of the azo dye, cyclic voltammetry (CV) and AC impedance methods were employed to examine the electrochemical behavior of graphite electrodes in pure and AM-modified 0.054 M Na\({}_{2}\)SO\({}_{4}\) solutions. Figure 2 shows the cyclic voltammograms recorded for both solutions over the potential range from \(-1.00\) to 1.00 V vs. SCE, obtained at room temperature with a sweep rate of 50 mV s\({}^{-1}\). \begin{table}
\begin{tabular}{c c} \hline \hline  & **MS/MS Parameters** \\ \hline Precursor ion (_m/z_) & 447.5 (AR357) \\ Product ions (_m/z_) & 442.5 (AV90) \\ Desolvation gas & nitrogen \\ Desolvation gas temperature (\({}^{\circ}\)C) & 350 \\ Desolvation gas flow (L/h) & 300 \\ Cone gas flow (L/h) & 150 \\ Collision gas & argon \\ Source’s temperature (\({}^{\circ}\)C) & 120 \\ Electrospray mode & negative \\ Cone voltage (V) & 20 \\ Capillary voltage (kV) & 3.0 \\ Retention time (min) & 0.89 (AV90) \\  & 1.10 (AR357) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Tandem mass spectrometry (MS/MS) parameters. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Source of Variation**} & \multicolumn{2}{c}{**Ir**} & \multicolumn{2}{c}{**Iy**} & \multicolumn{2}{c}{**FM**} & \multicolumn{2}{c}{**DM**} \\ \cline{2-7}  & _F-Value_ & \(p\) & _F-Value_ & \(p\) & _F-Value_ & \(p\) & _F-Value_ & \(p\) \\ \hline Intercept & 63.10554 * & 0.000000 & 82.17460 * & 0.000000 & 442.0006 * & 0.000000 & 781.8951 & 0.000000 \\ Solution type (S) & 25.82239 * & 0.000000 & 19.27117 * & 0.000000 & 37.3908 * & 0.000005 & 1.5545 & 0.259981 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Analysis of variance (ANOVA) for morphological features of _L. minor_ exposed to OM, ESS+OM; AM in ESS+OM; AM\({}_{\text{Cox}}\) in ESS+OM; AM\({}_{\text{Fe/Cuox}}\) in ESS+OM. The voltammogram in pure solution exhibited well-defined cathodic and anodic features related to Faradaic hydrogen and oxygen evolution reactions in the potential range from \(-1.10\) to \(-0.30\) V and from \(0.60\) to \(1.00\) vs. SCE, respectively. The rest of the CV profile could be associated with a double-layer charging process. Then, the addition of AM dye caused the appearance of two well-pronounced oxidation peaks (centered at about \(-0.25\) and \(0.10\) V vs. SCE) upon cycling in the direction of more positive potentials reaching current densities of \(0.05\) and \(0.22\) mA cm\({}^{-2}\), correspondingly. It is strongly believed that they are related to the surface oxidation of the studied dyes [36; 37]. Later, another two features were observed on the reverse scan, located from \(0.10\) to \(0.25\) and from \(-0.20\) to \(0.05\). These peaks are most presumably associated with the reduction of earlier electrooxidized by-products. A similar CV response was observed for the Fe working electrode of the Cu/Fe galvanic cell, where two oxidation peaks were also obtained under analogous conditions [18]. Nevertheless, they were centered in more negative regions than those for graphite electrodes and were centered at ca. \(-0.56\) and \(-0.42\) V vs. SEC. They were also characterized by higher current densities than those obtained in this work, namely \(2.0\) and \(3.8\) mA cm\({}^{-2}\). The above may suggest that iron has better catalytic properties than graphite for AM electrooxidation. The electrochemical spectroscopy impedance (EIS) behavior of the graphite electrode in pure and containing \(50\) mg dm\({}^{-3}\) of AM dye supporting a \(0.054\) M Na\({}_{2}\)SO\({}_{4}\) solution is shown in Figure 3A,B (the potentials of EIS measurements correspond to potentials of oxidation peaks from Figure 2). Hence, in the absence of the AM dye (Figure 3A) for the applied potential of \(-250\) mV vs. SCE, the Nyquist impedance plot (blue) exhibited two somewhat \"depressed\" semicircles, where it is strongly believed that the high-frequency and low-frequency semicircles were associated with the porosity of the electrode [38].