## 4 Conclusions  
This study presents a comprehensive kinetic analysis of the photo-Fenton degradation of SMX, a representative emerging micropollutant, under varying ferrous ion concentrations. The results confirm the high efficiency of the photo-Fenton process for the rapid elimination of SMX from aqueous systems, following first-order kinetics with respect to the pollutant concentration. The process also induces significant transformations in water quality indicators, including aromaticity and color, which were successfully modeled using first-order and series reaction kinetics. The degradation of SMX proceeds rapidly, yet the persistence of aromaticity and color in the water indicates the formation of stable intermediate products. These intermediates gradually degrade, with their transformation rates closely linked to the availability of hydroxyl radicals generated in situ. Increasing the concentration of Fe(II) accelerates all degradation pathways, although excessive dosages can promote radical scavenging and the formation of stable iron-organic complexes, which hinder complete mineralization and lead to residual color and aromaticity in the treated water. Moreover, the mineralization analysis through sulfur and nitrogen markers revealed distinct trends. Sulfate formation aligned well with stoichiometric predictions, confirming the oxidative cleavage of sulfonamide groups. Nitrate formation, however, displayed a non-linear dependence on Fe(II) concentration, with an optimal catalyst dosage of 0.5 mg/L maximizing nitrogen oxidation (22 mol SMX:1 mol Fe(II)). Higher Fe(II) concentrationsdiminished nitrate production, likely due to radical consumption by excess iron and the formation of stable Fe-aminophenol complexes that prevent full oxidation. These findings underscore the critical role of iron dosage in balancing the generation of reactive species and minimizing secondary effects such as complex formation, residual color, and incomplete mineralization. The proposed kinetic models provide a valuable framework for predicting treatment performance and optimizing operational conditions. Importantly, integrating photo-Fenton oxidation with subsequent biological treatments could enhance the overall bioremediation efficiency, enabling the complete removal of emerging contaminants and their transformation products. This work contributes to advancing bioremediation technologies by offering mechanistic insights and kinetic modeling tools that facilitate the design of effective treatment strategies for the abatement of pharmaceutical micropollutants in water. Although a biological treatment phase was not included in this study, the results provide a solid foundation to propose the use of photo-Fenton processes as a pre-treatment in bioremediation systems. The reduction of the initial pollutant load, the fragmentation of recalcitrant structures, and the decrease in toxic compounds are key factors that could enhance the efficiency of conventional biological processes. Consequently, future studies should focus on the experimental validation of this integrated approach through biodegradability tests, toxicity bioassays, and assessments of microbial activity on partially oxidized effluents. This integrated strategy would not only enable higher removal rates of emerging contaminants but also contribute to the development of more sustainable and effective water treatment technologies. Conceptualization, N.V.; methodology, U.D. and E.B.-G.; software, U.D., E.B.-G. and N.V.; validation, N.V., U.D. and E.B.-G.; formal analysis, U.D., E.B.-G. and N.V.; investigation, E.B.-G., N.V. and U.D. ; resources, U.D., N.V. and E.B.-G.; data curation, U.D., E.B.-G. and N.V.; writing--original draft preparation, N.V. and U.D. ; writing--review and editing, N.V.; visualization, N.V. and U.D. ; supervision, N.V.; project administration, N.V.; funding acquisition, N.V. All authors have read and agreed to the published version of the manuscript. This research was funded by PIBA_2023_01_0032--Basic and/or Applied Research Project.