さらば、永遠の化学物質。PFASの永久追放を目指す研究者たち(Farewell, Forever Chemicals: Researchers Aim to Eliminate PFAS for Good)

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2022-03-31 ミシガン工科大学

・ミシガン工科大学で開発された新しい計算ツールは、PFAS(ペルフルオロアルキル物質およびポリフルオロアルキル化合物)と呼ばれる残留性化学物質を地域の水源から排除するための緊急課題を支援するものです。
・PFASは、そのユニークな特性から、撥水加工された衣類や焦げ付きにくい調理器具、ピザの箱、スキーワックス、ファーストフードの包み紙、消火用泡など、日常生活のあらゆるところで使用されています。
・「PFASは非常に強い炭素-フッ素結合を持ち、生物活動によって容易に分解されません。PFASは、ほぼ永遠に環境中に存在し続けるため、”永遠の化学物質 ”と呼ばれています。地下水や地表水、水路、そして最終的には飲料水や生態系(淡水魚を含む)も汚染してしまう。」と、土木・環境・地理空間工学の南方大輔准教授は語る。

<関連情報>

水相の高度な還元プロセスにおける水和電子と有機化合物の反応性 Reactivities of hydrated electrons with organic compounds in aqueous-phase advanced reduction processes

Rose Daily  and  Daisuke Minakata Royal Society ofChemistry

Abstract

Advanced reduction processes (ARPs) that generate reactive electrons in homogeneous solution and heterogeneous electrochemical or catalytic processes are effective in degrading oxidized forms of organic and inorganic contaminants. However, the detailed mechanisms of compounds with multiple functional groups and the effect of those functional groups on the reactivities of these compounds toward electrons have not been elucidated. In this study, we use density functional theory to calculate the aqueous-phase one electron reduction potential Image ID:d1ew00897h-t1.gif of 251 conventional organic compounds containing a wide variety of functional groups. We investigate three possible elementary reaction mechanisms, namely, the associative, concerted and stepwise cleavage mechanisms, at all possible reactive sites and determine the linear free energy relationships (LFERs) between the experimentally measured rate constants of hydrated electrons (eaq) and the Image ID:d1ew00897h-t2.gif values. In addition, we use the 75 priority per- and polyfluoroalkyl substance (PFAS) subsets from the United States Environmental Protection Agency (U.S. EPA) to calculate the Image ID:d1ew00897h-t3.gif values of all possible elementary reactions of each PFAS to determine their dominant reaction mechanisms and reactive sites. LFERs of conventional organic compounds are used to predict the reactivities of eaq with PFASs, which can be used as a screening tool to evaluate the electron-induced degradability of thousands of PFASs for both homogeneous and heterogeneous reduction processes. Finally, we develop a kinetic model to investigate the impact of an accurate rate constant prediction on the fate of an environmentally relevant organic compound induced by eaq in a homogeneous aqueous-phase ARP.

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