## 4 Discussion  
It can be highlighted that the adsorption mechanism of organic compounds onto metal oxides, such as alumina, likely follows similar pathways to those observed for the commercial dye degradation in the present study. Given that no significant shifts in peak values of maximum absorption, nor any evident bathochromic or hypochromic processes, were observed, the mechanism of capturing the organic compounds can be attributed to ligand exchange, surface complexation, and hydrophobic interactions, much like the sorption behavior of organic molecules onto metal oxide surfaces. As seen in the case of alumina, organic molecules such as those present in the dye mixture may interact weakly through non-polar interactions, though more strongly when functional groups capable of complexation are involved. This interaction may result in the formation of surface complexes that influence the extent of degradation during photoelectrochemical treatment. Furthermore, the observed increase in sediment and precipitate mass could be attributed to the precipitation of degradation byproducts or the formation of insoluble complexes that are captured on the electrode or within the solution, thus affecting the overall dye degradation process. These changes in the sediment and precipitate mass support the notion that surface interactions are central to the observed effects on dye molecules under experimental conditions. Figure 2 depicts the results of the evaluated parameters with and without UV light imposition (solid and dashed lines, respectively). The responses of the parameters are illustrated as follows: Figure 2a, fraction of dyes; Figure 2b, cell potential; Figure 2c, recovered mass; and Figure 2d, pH. In Figure 2a, the degraded fraction of each dye is shown, revealing that Erythrosine undergoes the highest degradation, followed by Tartrazine and Brilliant Blue. Additionally, an increase in the imposed current leads to greater degradation until reaching a plateau, indicating a mixed control of the reaction, initially electrochemical and subsequently photochemical. This is confirmed by observing higher degradation with UV light at higher imposed current values, suggesting photoelectrochemical control beyond 1 mA cm\({}^{-2}\). Figure 2b displays the potentiometric analysis results during current imposition, with and without UV light (solid and dashed lines, respectively). In both cases, the potential increases with current, reaching a stabilization plateau from 1 mA \(\times\) cm\({}^{-2}\) onwards, transitioning from charge transfer-limited to the availability of anode sites for oxidation. Notably, the cell potential is lower when UV light is imposed, suggesting that UV light contributes to the reaction's energy requirements. The observed behavior indicates that the system shifts from being limited by the electrochemical processes at lower currents to being governed by the availability of active sites on the anode at higher currents. The presence of UV light seems to reduce the overall energy demand of the system, potentially enhancing the oxidation of the dye molecules through synergistic photochemical reactions. The effect of current density on various parameters such as the fraction of degraded dyes, cell potential, recovered mass, and pH should be explored in greater detail. The current density plays a crucial role in determining the rate of degradation and the efficiency of the process. A higher current density typically leads to an increase in the production of reactive species, which enhances the degradation rate of the dyes but may also alter the pH, affecting the overall process efficiency. The relationship between current density and the fraction of degraded dyes is often nonlinear, with an optimal current density beyond which the efficiency may plateau or decrease due to side reactions or excessive energy consumption. Additionally, the recovered mass and pH should be analyzed to provide insight into the material balance and the chemical dynamics occurring during the degradation process.