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<p>Methyl paraben (MeP), an endocrine-disrupting preservative widely present in pharmaceuticals and personal care products (PPCPs), is frequently detected in aquatic environments and thus necessitates efficient remediation strategies. In this study, a UV-C-activated bromine (UV-C/bromine) process was investigated for the abatement of MeP, and its performance benchmarked against the UV-C/chlorine (UV-C/Cl), UV-C/hydrogen peroxide (UV-C/H<sub>2</sub>O<sub>2</sub>), and UV-C/persulfate (UV-C/PMS) processes under equivalent UV-C exposure conditions. The UV-C/bromine process achieved 91.3% MeP removal within 60&#xa0;min, outperforming UV-C/Cl, UV-C/H<sub>2</sub>O<sub>2</sub>, and UV-C/PMS by 23.5%, 62.3%, and 31.7%, respectively; response surface methodology (RSM) optimization further elevated the removal efficiency to 92.7%. A steady-state kinetic model established in MATLAB was employed to quantify radical contribution ratios, which identified HO· and Br· as the dominant oxidants and revealed a bromine dosage-dependent kinetic shift toward ·Br-dominated degradation. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis identified hydroxylation, decarboxylation and ring-opening as the primary degradation pathways. Brominated byproducts were transient intermediates, with Br-MeP and Br<sub>2</sub>-MeP reaching peak concentrations of 0.039 and 0.034 mmol·L⁻¹, respectively, whereas chlorinated analogues remained at negligible levels. ECOSAR-based toxicity predictions highlighted a clear performance-toxicity trade-off: oxidative/ring-opening intermediates were generally less toxic than the parent MeP compound, whereas brominated intermediates—particularly dihalogenated species—exhibited enhanced toxicity. The steady-state kinetic model developed in MATLAB quantitatively resolves the contributions of dominant radicals and predicts their steady-state concentrations under diverse water conditions, which provides a robust theoretical tool for revealing the intrinsic degradation mechanism of MeP in the UV-C/bromine system and guiding the rational design and operational optimization of halogen-based advanced oxidation processes.</p>

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UV-C-Activated bromine oxidation: A promising strategy for efficient degradation of methyl paraben —parameter optimization, kinetic behavior, and Quantum-Chemical Mechanistic insights

  • 期刊论文

  • 发表日期：

    2026年5月20日

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  • Wengang Zhang,
  • Bingqin Su,
  • Yuexing Wei,
  • Xiulan Song,
  • Haoxuan Kong,
  • Liang Feng

摘要

Methyl paraben (MeP), an endocrine-disrupting preservative widely present in pharmaceuticals and personal care products (PPCPs), is frequently detected in aquatic environments and thus necessitates efficient remediation strategies. In this study, a UV-C-activated bromine (UV-C/bromine) process was investigated for the abatement of MeP, and its performance benchmarked against the UV-C/chlorine (UV-C/Cl), UV-C/hydrogen peroxide (UV-C/H2O2), and UV-C/persulfate (UV-C/PMS) processes under equivalent UV-C exposure conditions. The UV-C/bromine process achieved 91.3% MeP removal within 60 min, outperforming UV-C/Cl, UV-C/H2O2, and UV-C/PMS by 23.5%, 62.3%, and 31.7%, respectively; response surface methodology (RSM) optimization further elevated the removal efficiency to 92.7%. A steady-state kinetic model established in MATLAB was employed to quantify radical contribution ratios, which identified HO· and Br· as the dominant oxidants and revealed a bromine dosage-dependent kinetic shift toward ·Br-dominated degradation. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis identified hydroxylation, decarboxylation and ring-opening as the primary degradation pathways. Brominated byproducts were transient intermediates, with Br-MeP and Br2-MeP reaching peak concentrations of 0.039 and 0.034 mmol·L⁻¹, respectively, whereas chlorinated analogues remained at negligible levels. ECOSAR-based toxicity predictions highlighted a clear performance-toxicity trade-off: oxidative/ring-opening intermediates were generally less toxic than the parent MeP compound, whereas brominated intermediates—particularly dihalogenated species—exhibited enhanced toxicity. The steady-state kinetic model developed in MATLAB quantitatively resolves the contributions of dominant radicals and predicts their steady-state concentrations under diverse water conditions, which provides a robust theoretical tool for revealing the intrinsic degradation mechanism of MeP in the UV-C/bromine system and guiding the rational design and operational optimization of halogen-based advanced oxidation processes.