Radical chemistry in atmospheric ice analogs forms persistent trifluoroacetic acid.

IF 8.1 1区化学 Q1 CHEMISTRY, MULTIDISCIPLINARY

Chemical Science Pub Date : 2026-10-06 DOI:10.1039/d6sc05084k

Mason McAnally, Koushik Mondal, Yuheng Luo, Nils W Melbourne, Pooja Chahal, Xilin Bai, Jinghui Lu, Baoyu Song, Xinxuan Wang, Andrew M Turner, Alexandre Bergantini, Souvick Biswas, Rui Sun, Tao Yang, Ralf I Kaiser

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引用次数: 0

Abstract

Trifluoroacetic acid (TFA, CF₃COOH), the most prevalent per- and polyfluoroalkyl substance (PFAS), is accumulating globally in precipitation, soils, and drinking water, yet its formation remains unresolved. Atmospheric models emphasize gas-phase oxidation of hydrofluorocarbons and hydrofluoroolefins, but measured abundances often exceed predictions, implying missing chemistry. Here, we identify a condensed-phase radical pathway to TFA in cryogenic trifluoromethane/carbon dioxide ice analogs. Energetic processing generates trifluoromethyl (CF₃) and hydroxycarbonyl (HOCO) radicals that undergo barrierless recombination to form TFA. Fourier transform infrared spectroscopy tracks reactive intermediates and carboxylic acid functional groups, while synchrotron vacuum-ultraviolet photoionization reflectron time-of-flight mass spectrometry provides isomer-selective detection of TFA and diagnostic dimer fragments. These results support CF₃-HOCO recombination as a potential condensed-phase route linking fluorocarbon degradation to persistent PFAS formation, highlighting the potential role of ice crystals and cloud particles as chemical reactors in atmospheric fluorine chemistry.

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大气冰类似物中的自由基化学形成持久性三氟乙酸。

三氟乙酸（TFA, CF3COOH）是最普遍的单氟烷基和多氟烷基物质（PFAS），在全球范围内积累在降水、土壤和饮用水中，但其形成仍未解决。大气模型强调氢氟碳化合物和氢氟烯烃的气相氧化，但测量到的丰度往往超过预测，这意味着缺少化学反应。在这里，我们确定了低温三氟甲烷/二氧化碳冰类似物中的冷凝相自由基途径。高能加工产生三氟甲基（CF3）和羟基羰基（HOCO）自由基，它们经过无障碍重组形成TFA。傅里叶变换红外光谱跟踪反应中间体和羧酸官能团，而同步加速器真空紫外光电离反射时间质谱提供TFA和诊断二聚体片段的异构体选择性检测。这些结果支持CF3-HOCO重组是一种潜在的凝聚相途径，将氟碳降解与持久性PFAS形成联系起来，突出了冰晶和云颗粒在大气氟化学中作为化学反应器的潜在作用。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Chemical Science CHEMISTRY, MULTIDISCIPLINARY-

CiteScore

14.40

自引率

4.80%

发文量

1352

审稿时长

2.1 months

期刊介绍： Chemical Science is a journal that encompasses various disciplines within the chemical sciences. Its scope includes publishing ground-breaking research with significant implications for its respective field, as well as appealing to a wider audience in related areas. To be considered for publication, articles must showcase innovative and original advances in their field of study and be presented in a manner that is understandable to scientists from diverse backgrounds. However, the journal generally does not publish highly specialized research.