Advanced oxidation processes that utilize peroxymonocarbonate (HCO₄^-), generated in-situ through the reaction of HCO₃^- and H₂O₂, are employed for the removal of pollutants in water. Nevertheless, the precise role of H₂O₂ in these processes remains a subject of debate. This study established a HCO₄^--based oxidation system using NaHCO₃ and H₂O₂ for the degradation of acetaminophen and investigated the activation mechanisms of coexisting oxidants. Under thermal activation conditions, the OO bond in HCO₄^- (HOOCOO^-) was more readily cleaved than the OO bond in the co-existing oxidant H₂O₂ (HOOH), leading to the generation of reactive oxygen species (ROS). Based on kinetics and ROS evaluation, H₂O₂ primarily served to form HCO₄^- rather than converting to ·OH or O₂, with HCO₄^- acting as the primary oxidant for degradation through the formation of ${\text{CO}}_3^{·-}$and ·OH. In this oxidation system, H₂O₂ utilization efficiency for ·OH production reached 27.34 %, ·OH yield reached 24.15 % and acetaminophen degradation efficiency realized 83 % at 60 °C with 20 mM HCO₃^- and 20 mM H₂O₂. The apparent activation energy of acetaminophen degradation and HCO₄^- activation were calculated as 90.83 kJ mol^-1 and 18.81 kJ mol^-1, respectively. Moreover, a novel CO₂-derived HCO₄^--based system led to a comparable acetaminophen degradation efficiency of 82 % and a higher k_obs of 0.028 min^-1. The system optimization and ROS evaluation suggest that high concentration of H₂O₂ inhibited the degradation and quenched ${\text{CO}}_3^{·-}$ and ·OH to yield ·O₂^- and ¹O₂. Furthermore, EPR analysis and quenching experiments indicate that ${\text{CO}}_3^{·-}$ was mainly responsible for acetaminophen degradation. This work provides fundamental understanding of the HCO₄^--based oxidation system.

中文翻译：

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过氧化氢在过氧单碳酸酯基氧化体系中对污染物控制的作用的再思考


利用通过 HCO₃^- 和 H₂O₂ 反应原位生成的过氧单碳酸酯 （HCO₄^-） 的高级氧化工艺用于去除水中的污染物。然而，H₂O₂ 在这些过程中的确切作用仍然是一个争论的话题。本研究利用 NaHCO₃ 和 H₂O₂ 建立了基于 HCO₄ 的氧化体系，用于降解对乙酰氨基酚，并研究了共存氧化剂的活化机制。在热活化条件下，HCO₄^- （HO OCOO^-） 中的 O O 键比共存的氧化剂 H₂O₂ （HO OH） 中的 O O 键更容易裂解，从而导致活性氧 （ROS） 的产生。根据动力学和 ROS 评估，H₂O₂ 主要用于形成 HCO₄^-，而不是转化为 ·OH 或 O_{2，HCO 4}^- 作为主要氧化剂，通过生成 ${\text{CO}}_3^{·-}$和 ·哦。在该氧化系统中，H₂O₂ 的利用效率为 ·OH 产量达到 27.34 %， ·OH 产率达到 24.15 %，对乙酰氨基酚降解效率在 60 °C 下达到 83 %，20 mM HCO₃ ^和 20 mM H₂O₂。 计算出对乙酰氨基酚降解和 HCO₄^- 活化的表观活化能分别为 90.83 kJ ^mol-1 和 18.81 kJ ^mol-1。此外，一种基于 CO₂ 衍生的 HCO₄ 的新型系统导致相当的对乙酰氨基酚降解效率为 82% 和更高的 k_obs 为 0.028 ^min-1。系统优化和 ROS 评价表明，高浓度的 H₂O₂ 抑制了 ${\text{CO}}_3^{·-}$ 和 ·OH 到产量 ·O₂^- 和 ¹O₂.此外，EPR 分析和猝灭实验表明，${\text{CO}}_3^{·-}$ 是导致对乙酰氨基酚降解的主要原因。这项工作提供了对基于 HCO₄ 的氧化系统的基本理解。