Dipartimento di Chimica, Università di Torino, Via Pietro Giuria 5, 10125, Torino, Italy.
Institut de Chimie de Clermont-Ferrand, Clermont Université, Université Blaise Pascal, F-63177, Aubière, France.
Chemosphere. 2019 Dec;237:124476. doi: 10.1016/j.chemosphere.2019.124476. Epub 2019 Jul 30.
The photoreactions sensitised by the excited triplet states of chromophoric dissolved organic matter (CDOM*) are very important in the photochemical attenuation of emerging contaminants in natural waters. Until quite recently, anthraquinone-2-sulphonate (AQ2S) was the only available CDOM proxy molecule to estimate the contaminant reaction kinetics with CDOM*, under steady-state irradiation conditions. Unfortunately, the AQ2S triplet state (AQ2S*) is considerably more reactive than average CDOM*. We have recently developed an alternative protocol based on 4-carboxybenzophenone (CBBP), the triplet state of which (CBBP*) is less reactive compared to AQ2S*. Here we show that in the case of ibuprofen (IBP), paracetamol (APAP) and clofibric acid (CLO), the reaction rate constants with CBBP* are more reasonable as CDOM* reactivity estimates than those obtained by using AQ2S. In contrast, similar rate constants are measured for the reaction of atrazine (ATZ) with either AQ2S* or CBBP*. Moreover, the reactivity of ATZ with both AQ2S* and CBBP* is very similar to that with CDOM*, available through a literature estimate. The possibility to validate the ATZ-CBBP* reactivity estimate against the CDOM* data, and to accurately predict the reported IBP and CLO field lifetime, support the suitability of CBBP as CDOM proxy. The replacement of AQ2S with CBBP as proxy molecule does not reverse the qualitative prediction, according to which CDOM* would be the main process involved in the photodegradation of the studied contaminants in waters with high dissolved organic carbon (DOC). However, the CBBP-based data prompt for an important reconsideration of the estimated lifetimes at high DOC.
受激发三线态发色溶解有机质（CDOM*）敏化的光反应在天然水中新兴污染物的光化学衰减中非常重要。直到最近，蒽醌-2-磺酸盐（AQ2S）一直是唯一可用的 CDOM 探针分子，可用于在稳态辐照条件下估计污染物与 CDOM的反应动力学。不幸的是，AQ2S 的三线态（AQ2S）比平均 CDOM的反应性要强得多。我们最近开发了一种基于 4-羧基二苯甲酮（CBBP）的替代方案，其三线态（CBBP）的反应性比 AQ2S 低。在这里，我们表明，在布洛芬（IBP）、对乙酰氨基酚（APAP）和氯菲酸（CLO）的情况下，与 CBBP的反应速率常数作为 CDOM反应性的估计值比使用 AQ2S 得到的更合理。相比之下，用 AQ2S或 CBBP测量的 ATZ 的反应速率常数相似。此外，ATZ 与 AQ2S和 CBBP的反应性与通过文献估计获得的 CDOM非常相似。用 CBBP 作为 CDOM 探针可以通过将 ATZ-CBBP反应性估计值与 CDOM数据进行验证，并准确预测报告的 IBP 和 CLO 现场寿命，从而验证其适用性。用 CBBP 替代 AQ2S 作为探针分子不会改变定性预测，即 CDOM将是高溶解有机碳（DOC）水中研究污染物光降解的主要过程。然而，基于 CBBP 的数据促使我们对高 DOC 下估计的寿命进行重要的重新考虑。
