The exposed hematite surface and the generation of environmentally persistent free radicals during catechol degradation,Environmental Science: Processes & Impacts

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The exposed hematite surface and the generation of environmentally persistent free radicals during catechol degradation
Environmental Science: Processes & Impacts ( IF 4.3 ) Pub Date : 2020-11-16 , DOI: 10.1039/d0em00416b
Ziyu Zhao _{1,

2,

3,

4,

5} , Quan Chen _{1,

2,

3,

4,

5} , Hao Li _{1,

2,

3,

4,

5} , Di Lang _{1,

2,

3,

4,

5} , Meixuan Wu _{1,

2,

3,

4,

5} , Dandan Zhou _{1,

2,

3,

4,

5} , Bo Pan _{1,

2,

3,

4,

5} , Baoshan Xing _{6,

7,

8,

9}

Affiliation

Environmentally persistent free radicals (EPFRs) have drawn increasing attention. It is reported that EPFR formation is dependent on the presence of transition metals; however the size of the metal particles is ignored. In this study, we hypothesized that transition metals in smaller particle sizes could more efficiently promote the generation of EPFRs and thus have higher risks. Nanosized hematite (nanoHMT) and microsized hematite (microHMT) were studied and compared. We monitored the degradation of catechol and the generation of EPFRs under both dark and ultraviolet light conditions. Catechol degradation was inhibited in the presence of hematite in the dark, with more significant inhibition by nanoHMT. However, under ultraviolet light, catechol degradation was promoted by hematite, with more significant promotion by nanoHMT. The yield of free radicals in the nanoHMT system was always higher than that in the microHMT system. More dimers were detected in the nanoHMT system, which may have played an important role in stabilizing free radicals. More trivalent Fe was converted to divalent Fe in the nanoHMT system than in the microHMT system. The relatively more active sites for the catechol interaction promoted EPFR generation. These results highlighted that size-dependent reactions should be well considered when predicting the environmental behavior and risks of organic contaminants.

中文翻译：

邻苯二酚降解过程中裸露的赤铁矿表面和环境持久性自由基的产生

环境持久性自由基（EPFR）已引起越来越多的关注。据报道，EPFR的形成取决于过渡金属的存在。然而，金属颗粒的尺寸被忽略了。在这项研究中，我们假设较小粒径的过渡金属可以更有效地促进EPFR的生成，因此具有更高的风险。研究和比较了纳米赤铁矿（nanoHMT）和微型赤铁矿（microHMT）。我们在黑暗和紫外线条件下监测了儿茶酚的降解和EPFR的产生。在黑暗中有赤铁矿存在时，邻苯二酚的降解受到抑制，而nanoHMT则具有更明显的抑制作用。然而，在紫外光下，赤铁矿促进了儿茶酚的降解，而nanoHMT促进了邻苯二酚的降解。nanoHMT系统中的自由基产率始终高于microHMT系统中的自由基产率。在nanoHMT系统中检测到更多的二聚体，这可能在稳定自由基方面发挥了重要作用。与microHMT系统相比，nanoHMT系统中更多的三价Fe转化为二价Fe。邻苯二酚相互作用的相对活跃的位点促进了EPFR的产生。这些结果表明，在预测环境行为和有机污染物的风险时，应充分考虑与尺寸有关的反应。与microHMT系统相比，nanoHMT系统中更多的三价Fe转化为二价Fe。邻苯二酚相互作用的相对活跃的位点促进了EPFR的产生。这些结果表明，在预测环境行为和有机污染物的风险时，应充分考虑与尺寸有关的反应。与microHMT系统相比，nanoHMT系统中更多的三价Fe转化为二价Fe。儿茶酚相互作用的相对较活跃的位点促进了EPFR的产生。这些结果表明，在预测环境行为和有机污染物的风险时，应充分考虑与尺寸有关的反应。

更新日期：2020-12-10

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