抗氧化基团在溶解有机物猝灭嘌呤自由基中的作用,Environmental Science & Technology

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抗氧化基团在溶解有机物猝灭嘌呤自由基中的作用
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2021-11-08 , DOI: 10.1021/acs.est.1c04576
Shuangshuang Cheng ₁ , Yujie Zhao ₁ , Yanheng Pan ₁ , Jinpeng Yu ₁ , Yu Lei ₁ , Xin Lei ₁ , Gangfeng Ouyang ₂ , Xin Yang ₁

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众所周知，溶解有机物 (DOM) 在高级氧化过程中会抑制痕量有机污染物 (TrOCs) 的降解，但缺乏定量的认识。腺嘌呤 (ADN) 被选为模型 TrOC，因为在 TrOCs 中广泛存在嘌呤基团，并且其中间自由基的瞬态光谱有据可查。使用稳态光化学实验、时间分辨光谱和动力学模型对 UV/过硫酸盐处理过程中存在 DOM 的 ADN 降解进行了量化。发现 DOM 的抑制作用包括竞争光子、清除 SO ₄^•–和 HO ^•以及将中间 ADN 自由基 (ADN(-H) ^• ) 转换回 ADN。ADN(-H) 的一半^•_{在大约 0.2 mg C} L ^–1的 DOM存在下，被还原为 ADN 。^{ADN(-H) •}的淬灭速率常数由 10 个测试的 DOM 分离物在 (0.39–1.18) × 10 ⁷ M _C^–1 s ^–1范围内。它们与DOM的总抗氧化能力呈正线性关系。氧化还原活性基团的低分子量类似物的激光闪光光解结果进一步支持了 DOM 中的抗氧化基团在 ADN(-H) ^•猝灭中的主导作用。在预测高级氧化过程中 TrOCs 的减少时，应考虑 DOM 的不同作用。

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Role of Antioxidant Moieties in the Quenching of a Purine Radical by Dissolved Organic Matter

Dissolved organic matter (DOM) has been known to inhibit the degradation of trace organic contaminants (TrOCs) in advanced oxidation processes but quantitative understanding is lacking. Adenine (ADN) was selected as a model TrOC due to the wide occurrence of purine groups in TrOCs and the well-documented transient spectra of its intermediate radicals. ADN degradation in the presence of DOM during UV/peroxydisulfate treatment was quantified using steady-state photochemical experiments, time-resolved spectroscopy, and kinetic modeling. The inhibitory effects of DOM were found to include competing for photons, scavenging SO₄^•– and HO^•, and also converting intermediate ADN radicals (ADN(-H)^•) back into ADN. Half of the ADN(-H)^• were reduced back to ADN in the presence of about 0.2 mg_C L^–1 of DOM. The quenching rate constants of ADN(-H)^• by the 10 tested DOM isolates were in the range of (0.39–1.18) × 10⁷ M_C^–1 s^–1. They showed a positive linear relationship with the total antioxidant capacity of DOM. The laser flash photolysis results of the low-molecular-weight analogues of redox-active moieties further supported the dominant role of antioxidant moieties in DOM in the quenching of ADN(-H)^•. The diverse roles of DOM should be considered in predicting the abatement of TrOCs in advanced oxidation processes.

更新日期：2022-01-04

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