## 4 Conclusions  
The band-gap calculation for TiO\({}_{2}\) P25 showed a value of 3.2 eV, lower than the values shown in other TiO\({}_{2}\) semiconductors obtained by the sol-gel method with titanium tetrabutoxide (TBT) and titanium tetraisopropoxide (TIPT) as precursors. This result indicates faster activation of the photocatalysts TiO\({}_{2}\) P25 to the exposure to high radiation emission, in this case, solar energy. For solar photocatalysis with a 0.1 m\({}^{2}\) FPR surface, the COD analysis showed a significant degradation at a pH of 4.15, without the addition of H\({}_{2}\)O\({}_{2}\), obtaining a percentage of 27% for COD removal, 60 min after the start of the reaction, and 46.9% of the decrease in COD, in an extended reaction time of 80 min. At pH 3.5, 7, and 9, no degradation by solar photocatalysis was observed, with or without H\({}_{2}\)O\({}_{2}\) addition, for both 0.1 and 1 m\({}^{2}\) FPR surfaces. With the use of 1 m\({}^{2}\) FPR, a significant percentage degradation by COD was obtained at pH 4.15, 65% of COD removal with the addition of H\({}_{2}\)O\({}_{2}\) (4 mM) after 60 min of reaction, and up to 72% when the reaction was extended to 80 min. For the experiments without adding H\({}_{2}\)O\({}_{2}\). AMX degradation reached 100% of COD removal after 50 min, with no observable change up to 80 min of reaction. The results of the chemical kinetics of the AMX degradation in aqueous solution for the heterogeneous solar photocatalysis process, carried out under pH 4.15, without the addition of H\({}_{2}\)O\({}_{2}\), show first order reaction (n = 1), on both surfaces of 0.1 and 1 m\({}^{2}\) FPR, with magnitudes of K\({}_{\rm phC}\) = 0.013 min\({}^{-1}\) and K\({}_{\rm phC}\) = 0.10 min\({}^{-1}\), respectively. A greater exposed reaction surface (FPR 1 m\({}^{2}\) = 10 FPR 0.1 m\({}^{2}\)) favors the degradation of AMX under similar conditions of the reaction parameters, and also favors the reaction rate, defining the solar photocatalysis reaction in for a 1 m\({}^{2}\) FPR, the experimental magnitude of pH 4.15 and the absence (0 mM) of H\({}_{2}\)O\({}_{2}\), as the best AMX degradation conditions in this work. The H\({}_{2}\)O\({}_{2}\) doses (nil and 4 mM) showed significant differences within the first 20 min of the reaction for the 0.1 m\({}^{2}\) surface FPR, as well as for the 1 m\({}^{2}\) surface by ANCOVA and by a Tukey test. The FPR surface showed significant differences in the processes, during the entire reaction time (from 0 to 60 min), statistically confirming that a greater reaction surface on FPR favors the degradation of AMX, as well as the speed of the reaction. Data curation, T.L.A.-M. and J.B.P.-N.; formal analysis, T.L.A.-M., I.C.-H., A.A.L.-S., C.M.N.-N. and J.B.P.-N.; funding acquisition, J.B.P.-N.; investigation, T.L.A.-M.; methodology, T.L.A.-M., I.C.-H., A.A.L.-S., C.M.N.-N. and J.B.P.-N.; project administration, J.B.P.-N.; resources, J.B.P.-N.; supervision, C.M.N.-N. and J.B.P.-N.; validation, J.B.P.-N.; writing--original draft, T.L.A.-M.; writing--review and editing, C.M.N.-N. and J.B.P.-N. All authors have read and agreed to the published version of the manuscript. Funding: First author wishes to extend their gratitude to the Consejo Nacional de Humanidades, Ciencias y Tecnologias (CONAHCyT) for the scholarship granted to carry out the doctorate. Authors thank Instituto Politecnico Nacional (Project SIP:20221709 and SIP:20230110) for financing this project. The project does not necessarily reflect the views and policies of the funding organizations. Data Availability Statement: Data is contained within the article. The authors wish to acknowledge the Planta de Tratamiento de Aguas Residuales Oriente de Durango, Dgo., Mexico for providing the additional facilities to carry out the research, to the Advanced Materials Research Center (CIMAV-Durango) for the analysis of the samples and to the National Energy Conversion and Storage Laboratory (LNCAE) of CICATA-Legaria, IPN, for allowing us access to its experimental facilities and analysis equipment.