## 3 Results
### Dye Removal Assessment  
As the electrochemical decomposition characteristics and analysis of the by-products of the AM dye were already extensively described in previous work from this laboratory [18], this article will focus on the quantitative evaluation of AM dye removal methods. The efficiency of the electrooxidation and biodegradation processes of the examined AM azo dye for different experimental setups was evidenced by utilizing UV-Vis spectrophotometry and UPLC-MS/MS analysis (see Table 5 and Table 6, respectively). Hence, based on UV-Vis spectrophotometry results (Table 5), the total quantitative removal of the AM dye after 1h of continuous electrolysis yielded ca. 35 and 40% for AM\({}_{\text{Cox}}\) in ESS+OM and AM\({}_{\text{Fe/Cuox}}\) in ESS+OM conditions, respectively. This is in line with the electrochemical results, which suggest that the Fe electrode could possess superior catalytic properties toward AM dye oxidation compared to the graphite electrode. Then, after 7 days of exposure to the _L. minor_, the total removal of the researched dyes came to about 49, 63 and 68% for AM in ESS+OM, AM\({}_{\text{Cox}}\) in ESS+OM and AM\({}_{\text{Fe/Cuox}}\) in ESS+OM solutions, correspondingly. The above shows that _L. minor_'s outstanding removal ability of AM dye could be further enhanced by applying pretreatment, such as electrooxidation. A similar trend of the AM dye's removal was evidenced by UPLC-MS/MS analysis (see Table 6). Nevertheless, compared with the UV-Vis spectrophotometry method, the degree of AM dye removal registered by UPLC-MS/MS analysis was significantly higher. The above most likely results from the selectivity discrepancy between these two analytical methods. Then, the final removal of AV90 and AR357 dye components was 98 and over 99%, respectively, for both AM\({}_{\text{Cox}}\) in ESS+OM and AM\({}_{\text{Fe/Cuox}}\) in ESS+OM solutions. \begin{table}
\begin{tabular}{c c c} \hline
**Solution** & **Visible Symptoms** \\ \hline OM & & \\ \hline \end{tabular}
\end{table} 
Table 4: The leaves of \(L\). _minor_ were exposed to OM, ESS+OM; AM in ESS+OM; AM\({}_{\text{Cox}}\) in ESS+OM; AM\({}_{\text{Fe/Cuox}}\) in ESS+OM. \begin{table}
\begin{tabular}{c c c} \hline
**Sample** & **Concentration of Dye** & **Decrease in the Dye** \\  & **(mg dm\({}^{-3}\))** & **Concentration (\%) (Total)** \\ \hline AM in ESS+OM & & 23.057 & - \\ (before incubation) & & \\ AM in ESS+OM & & 11.803 & 49 \\ (after incubation) & & \\ AM\({}_{\text{Cox}}\) in ESS+OM & & 14.921 & 35 \\ (before incubation) & & \\ AM\({}_{\text{Cox}}\) in ESS+OM & & 8.451 & 43 (63) \\ (after incubation) & & \\ AM\({}_{\text{Fe/Cuox}}\) in ESS+OM & & 13.653 & 40 \\ (before incubation) & & \\ AM\({}_{\text{Fe/Cuox}}\) in ESS+OM & & 7.466 & 45 (68) \\ (after incubation) & & \\ \hline \end{tabular}
\end{table} 
Table 5: Quantitative dye assay was recorded for a wavelength of 500 nm. Furthermore, Table 7 presents the efficiencies of other azo dyes' degradation methods described in the literature. It should be noted that direct comparison of efficiencies with literature is quite problematic, as even similar methods have different starting and final conditions, such as time of the experiment and applied current densities, amount of used plants or starting dye concentration. Nevertheless, after considering all the conditions, the techniques employed in this work could be considered promising alternatives or additions to commonly used degradation methods. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Sample** & **Peak Area** \\
**AV90** & **AR357** \\ \hline AM in ESS+OM (before incubation) & 614,605 & 116,270 \\ AM in ESS+OM (after incubation) & 55,637 & 1918 \\ AM\({}_{\text{Cox}}\) in ESS+OM (before incubation) & 58,070 & 2205 \\ AM\({}_{\text{Cox}}\) in ESS+OM (after incubation) & 12,269 & 93 \\ AM\({}_{\text{Fe/Cuox}}\) in ESS+OM (before incubation) & 47,203 & 1516 \\ AM\({}_{\text{Fe/Cuox}}\) in ESS+OM (after incubation) & 10,112 & 120 \\ \hline \hline \end{tabular}
\end{table}