## 3 Results and Discussion
### Study of the Photo-Oxidation Kinetics of AHMPD with Polymers P2, P3, and P4 as Photosensitizers  
The ability of polymers P2-P4 was tested in the photodegradation reaction of AHMPD, where the absorption of AHMPD (5 \(\times\) 10\({}^{-6}\) M) was monitored at 270 nm as a function of time using photosensitizers P2, P3, and P4. The experiments were conducted at pH = 7 and pH = 11. Control experiments performed in the dark and in the absence of a photosensitizer showed no adsorption of the compound on the polymers nor degradation of AHMPD by direct irradiation in any case. According to the literature, the degradation of AHMPD by singlet oxygen produced by Rose Bengal follows a first-order kinetic pattern and has been studied in an aqueous solution. The experimental evidence suggests a charge-transfer-mediated mechanism involving the formation of an initial encounter excited complex [36]. In this context, first-order kinetics were determined for P2, P3, and P4 by fitting the value of the absorption maximum at 270 nm as a function of time (AHMPD, 5 \(\times\) 10\({}^{-6}\) M) and the experiments were carried out for both pH = 7 and pH = 11 media. The irradiation was performed using a 125 W medium-pressure Hg vapor lamp, which was surrounded by an aqueous solution of FeCl3 (0.1 M) used as a filter for wavelengths below 450 nm in order to avoid the degradation of AHMPD by direct photolysis, as well as the possible degradation of Rose Bengal by the action of the UV fraction of the light emitted by the lamp. It is noteworthy that the results obtained with respect to the decrease in the UV-Vis AHMPD absorption band (Figure 3) are comparable to those reported in the literature. On the other hand, the results also confirmed first-order kinetics in all cases; however, the reaction time was significantly slower than that reported in the reference work with unsupported RB, with reaction times in minutes instead of hours, as in the case of P2-P4. [36]. The results obtained for first-order kinetics are presented in Figure 4.  
Figure 2: Illustration of the normalized UV–Vis absorption spectra for polymers P1–P4 and Rose Bengal (Milli-Q water, 6 \(\upmu\)M). The first-order kinetics values are presented in Table 1 with the observed rate constants (\(k_{obs}\)) obtained by fitting the conversion data over time (first-order kinetics) and the final conversions achieved for each photosensitizer at pH = 7 and pH = 11. \begin{table}
\begin{tabular}{c c c c} \hline  & **Photosensitizer** & **Water (pH = 7)** & **Water (pH = 11)** \\ \hline P2 & \begin{tabular}{c} Conversion (\%) \\ \(k_{obs}\) (10\({}^{-4}\) h\({}^{-1}\)) \\ \end{tabular} & 7.4 & 214 \\ P3 & \
\begin{tabular}{c} Conversion (\%) \\ \(k_{obs}\) (10\({}^{-4}\) h\({}^{-1}\)) \\ \end{tabular} & 27.5 & 294 \\ P4 &
\begin{tabular}{c} Conversion (\%) \\ \(k_{obs}\) (10\({}^{-4}\) h\({}^{-1}\)) \\ \end{tabular} & 30.1 & 385 \\ \hline \end{tabular}
\end{table} 
Table 1: Conversions and first-order constants for P1, P2, and P3 (t = 48 h). Figure 4: First-order kinetics for P2, P3, and P4 (measured in wavelength absorption maximum at 270 nm) in pH = 11. Figure 3: Decreasing absorption band of AHMPD (5 \(\times\) 10\({}^{-6}\) M, pH = 11) at 270 nm using P2 as photosensitizer. As observed, the degradation is significantly more effective at pH = 11, achieving a conversion of 84% after 48 h of reaction with photosensizer P4. Additionally, polymers P3 and P4 exhibit higher performance than P2, which demonstrates the efficacy of grafting with ethylenediamine and \(\gamma\)-gluconolactone to improve the hydrophilicity of the polymeric matrices, compared to the nonpolar polymers P1 and P2, these results are comparable to prior research [19; 20]. In addition to testing the ability of P2-P4 to promote the degradation of AHMPD in aqueous solutions at pH = 7 and pH = 11, the ability to generate singlet oxygen was also studied for the three photosensizers as a control.