## 3 Results and Discussion
### Photocatalytic Tests
#### 3.2.1 Effect of Catalyst-H\({}_{2}\)O\({}_{2}\) Ratio  
A detailed study varying the amount of catalyst and H\({}_{2}\)O\({}_{2}\) added during the photo-Fenton-like process was carried out. Amounts of catalyst between 25 and 100 mg and H\({}_{2}\)O\({}_{2}\) between 1.96 and 235.50 mM were tested. Figure 6c illustrates the results obtained under different catalyst-H\({}_{2}\)O\({}_{2}\) molar ratios, revealing the influence of H\({}_{2}\)O\({}_{2}\) concentration on the reaction kinetics. As the catalyst-H\({}_{2}\)O\({}_{2}\) ratio increases, the degradation rate improves significantly, as evidenced by the steeper curves and lower dye concentrations observed for higher ratios. Specifically, at a ratio of 1:15, nearly complete dye removal was achieved within 45 min, with no detectable concentration remaining beyond this point. Similarly, at a ratio of 1:5, degradation progresses rapidly but at a slightly slower rate, achieving complete removal by 75 min. In contrast, the lower ratios, 1:0.5 and 1:2, exhibit slower degradation rates. For the 1:0.5 ratio, the process is remarkably inefficient, with approximately 35% of the dye remaining after 90 min, suggesting insufficient H\({}_{2}\)O\({}_{2}\) availability to generate enough reactive species. The 1:2 ratio shows improved performance compared to 1:0.5, but it was still much less efficient than the higher ratios, which emphasizes the importance of optimizing the H\({}_{2}\)O\({}_{2}\) concentration for effective degradation. The dashed lines in the graph represent the pseudo-first-order kinetic fit for all experiments with R\({}^{2}\) values greater than 0.98, indicating that the degradation process follows pseudo-first-order kinetics. The kinetic constants, obtained from the pseudo-first-order kinetic fitting, are presented in Figure 6d. These kinetic constants provide a quantitative measure of the degradation rates observed in each experiment. As the catalyst-H\({}_{2}\)O\({}_{2}\) ratio increased, the value of the constant increased significantly. The highest value was observed for the ratio 1:15, confirming the rapid elimination of Rhodamine B under these conditions. On the contrary, the 1:0.5 and 1:2 ratios showed considerably lower k values, correlating with the gentler slopes of their respective degradation profiles. These results are consistent with AOPs, where the \(\cdot OH\) generated from H\({}_{2}\)O\({}_{2}\) serves as the main oxidizing agent responsible for the degradation of pollutants. The faster kinetics observed at higher concentrations of H\({}_{2}\)O\({}_{2}\) can be attributed to a higher production of the \(\cdot OH\) radical, which accelerates the decomposition of Rhodamine B. However, excessively high concentrations of H\({}_{2}\)O\({}_{2}\) could potentially lead to radical-scavenging effects, as was highlighted in previous studies [60; 61]. Specifically, the recombination of \(\cdot OH\) radicals (Equation (16)) becomes more frequent, reducing the availability of active radicals. In addition, H\({}_{2}\)O\({}_{2}\) can react with \(\cdot OH\) radicals to produce less-reactive species, such as \(HO_{2}\) radicals (Equation (17)), which reduces the overall efficiency of the degradation process [62; 63]. These findings highlight the critical role of H\({}_{2}\)O\({}_{2}\) in improving the reaction rate while emphasizing the importance of optimizing the catalyst-to-H\({}_{2}\)O\({}_{2}\) ratio to achieve maximum process efficiency and sustainability. \[OH+\cdot OH\to H_{2}\text{O}_{2} \tag{16}\]\[OH+H_{2}O_{2}\to H_{2}O+HO_{2} \tag{17}\]  
Finally, the optimized results obtained for the photocatalysis and photo-Fenton like were compared with those obtained in other recent studies to evaluate the effectiveness of the synthesized material. In analyzing the degradation values obtained by the present study, the total degradation was achieved after 3 h of treatment, which is slow compared to other studies already carried out (Table 1), but the power of the lamps used in those cases is between three and five times higher.