Doctorado en Ingeniería Ambiental · 2026

Comparative evaluation of peracetic acid-based advanced oxidation processes for the degradation of emerging pollutants

Resumen

The increasing prevalence of contaminants of emerging concern (CECs), particularly recalcitrant pharmaceutical compounds such as Carbamazepine (CBZ) and Diclofenac (DCF), in aquatic environments necessitates the development of robust and efficient remediation technologies. Conventional wastewater treatment plants (WWTPs) are frequently ill-equipped to ensure the complete removal of these persistent micropollutants, leading to their discharge into receiving water bodies. Consequently, Advanced Oxidation Processes (AOPs) have garnered significant attention as a promising suite of technologies capable of degrading these refractory compounds. While traditional AOPs, primarily those utilizing hydrogen peroxide (H2O2) as the oxidant precursor (e.g., Fenton, photo-Fenton, UV/H2O2), have been extensively investigated, they often possess inherent limitations related to operational pH constraints, reaction kinetics, and oxidant utilization efficiency. Peracetic acid (PAA) has recently emerged as a viable alternative oxidant, characterized by a lower peroxide bond energy compared to H2O2, which suggests a higher potential for efficient activation. The primary objective of this research, therefore, was to conduct a systematic and comparative evaluation of PAA-based AOPs, specifically Fenton-like (Fe2+/PAA), photolytic (UV/PAA), and photo-Fenton-like (UV/Fe2+/PAA) activation, benchmarked directly against their conventional H2O2-based counterparts under optimized conditions. To achieve this, Response Surface Methodology (RSM) was employed to systematically optimize key operational parameters (e.g., pH, oxidant concentration, Fe2+ catalyst dose) for all six systems, ensuring a methodologically consistent and fair comparison. The investigation quantified degradation performance by determining apparent pseudo-first-order rate constants (kobs) via the initial rate method. Furthermore, mechanistic insights were sought by elucidating the relative contribution of different radical species (e.g., •OH, CH3COO•) using selective scavenging agents. The influence of a real surface water matrix on process efficiency was also assessed. Finally, transformation products (TPs) generated during the degradation of CBZ and DCF in the optimized PAA systems were identified using UPLC-MS/MS, and their potential ecotoxicity was estimated using QSAR models to provide a holistic assessment of the treatment efficacy. The results consistently demonstrated that PAA-based systems exhibited distinct advantages over their H2O2-based counterparts. Notably, in the iron-activated systems (Fe2+/PAA and UV/Fe2+/PAA), PAA achieved significantly faster degradation kinetics (e.g., kobs = 0.64 min⁻¹) compared to the H₂O₂ processes (e.g., kobs = 0.32 min⁻¹), reaching >99% degradation in shorter reaction times (15 min vs. 30 min). Moreover, the Fe²⁺/PAA system for CBZ degradation operated optimally at a higher initial pH of 4.2, offering a potential advantage over the strict pH 3 requirement of the Fenton process. In the photolysis-only (UV/PAA) system, while the observed kobs (0.15 min⁻¹) was found to be statistically comparable to that of the UV/H2O2 process (0.13 min⁻¹), this was achieved using a 4.8-fold lower molar concentration of oxidant (0.42 mM PAA vs. 2.0 mM H2O2). This finding highlights a substantially greater oxidant utilization efficiency for PAA under photolytic activation. In conclusion, this work validates that PAA-based AOPs are potent and highly efficient alternatives to traditional H2O2 systems for the remediation of persistent pharmaceuticals. The findings demonstrate clear advantages, either in the form of accelerated reaction kinetics or superior reagent efficiency, positioning PAA as a promising oxidant for integration into advanced water treatment trains.

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