The binding between dissolved organic matter (DOM) and micro-pollutants (MPs) results in significant impacts on their migration, transformation and degradation. However, the role of the DOM/MP binding on their oxidative transformation remains poorly studied. The binding of MPs by DOM, in combination with DOM's roles as a photosensitizer and/or a competitor for free radicals, needs to be considered in the context of understanding the DOM's impacts on the oxidative degradation of MPs. This study aims to explore this aspect of DOM/MP interactions based on the quantitation of humic acid (HA) and tetracycline (TET) complexation and its role in TET removal. This study also compared the degradation of free TET versus that bound in HA-TET complexes in different oxidation processes. Fourier transform infrared (FTIR) data show that the carboxyl and phenolic hydroxyl groups in HA are the main binding sites of TET, while nuclear magnetic resonance (NMR) analysis shows the binding of TET engages its -N(CH₃)₂ groups, and two-dimensional correlation spectroscopy (2D-COS) data show that the carboxyl groups in DOM are sensitive than phenolic groups in the binding of TET. The difference between the degradation rates (Δk_obs) of the free and bound TET decreased with the increase of ionic strength using sodium nitrate, but increased with the introduction of Ca²⁺ and Mg²⁺ due to the formation of TET-Ca²⁺/Mg²⁺ complexes. Quenching experiments showed that the free radicals (•OH and •SO₄⁻), PMS oxidant and UV light were the main contributors to the TET degradation in UV/PS, UV/PMS and UV/H₂O₂ processes, respectively. In-situ fluorescence time scanning and differential absorbance spectra showed that free TET was preferentially oxidized over the bound TET in all the tested treatments except UV/PS. These results provide new insights into the role of DOM/MP complexation in the degradation of MPs in natural and engineered systems.

溶解性有机物 (DOM) 与微污染物 (MPs) 之间的结合对其迁移、转化和降解产生重大影响。然而，DOM/MP 结合对其氧化转化的作用仍然缺乏研究。DOM 对 MPs 的结合，结合 DOM 作为光敏剂和/或自由基竞争者的作用，需要在理解 DOM 对 MPs 氧化降解的影响的背景下加以考虑。本研究旨在基于腐殖酸 (HA) 和四环素 (TET) 络合的定量及其在 TET 去除中的作用，探索 DOM/MP 相互作用的这一方面。该研究还比较了游离 TET 的降解与不同氧化过程中结合在 HA-TET 复合物中的降解。₃）_2个基团，二维相关光谱（2D-COS）数据表明，DOM中的羧基比酚基对TET的结合更敏感。游离和结合TET的降解速率(Δk _obs )之间的差异随着硝酸钠离子强度的增加而减小，但由于TET-Ca ²⁺的形成，随着Ca ²⁺和Mg ²⁺的引入而增大/Mg ²⁺络合物。淬火实验表明，自由基（•OH 和•SO ₄ ^-）、PMS 氧化剂和紫外光是导致 TET 在 UV/PS、UV/PMS 和 UV/H ₂ O _{2 中}降解的主要因素过程，分别。原位荧光时间扫描和差示吸收光谱表明，在除 UV/PS 之外的所有测试处理中，游离 TET 优先于结合 TET 氧化。这些结果为了解 DOM/MP 复合在自然和工程系统中 MP 降解中的作用提供了新的见解。