Activated Persulfate Oxidation of Perfluorooctanoic Acid (PFOA) in Groundwater under Acidic Conditions.
Activated Persulfate Oxidation of Perfluorooctanoic Acid (PFOA) in Groundwater under Acidic Conditions.
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酸性条件下地下水中全氟辛酸 (PFOA) 的活化过硫酸盐氧化
DOI：
10.3390/ijerph13060602
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发表时间：
2016-06-17
影响因子：
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通讯作者：
Lin N
中科院分区：
文献类型：
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作者：
Yin P;Hu Z;Song X;Liu J;Lin N
全氟辛酸 (PFOA) 因其对人类健康和生态系统的毒性而成为一种令人关注的新兴污染物。然而，采用经济有效的方法成功降解水溶液中的 PFOA 仍然是一个挑战，特别是对于地下水。在本研究中，研究了在温和条件下使用活化过硫酸盐降解 PFOA。在不同的实验条件下评估了不同因素对过硫酸盐活性的影响，包括pH、温度（25℃–50℃）、过硫酸盐用量和反应时间。与传统的碱活化过硫酸盐氧化相反，我们发现在酸性条件下使用活化过硫酸盐可以有效降解PFOA，其降解动力学遵循伪一级衰减模型。较高的温度、较高的过硫酸盐剂量和较长的反应时间通常会导致较高的 PFOA 降解效率。实验结果表明，在pH为2.0、反应温度50℃、PFOA与过硫酸盐摩尔比为1:100、反应时间100 h的条件下，活化过硫酸盐对PFOA的降解效率可达89.9%。该条件下相应的脱氟率为23.9%，表明并非所有PFOA均通过除氟分解。电子顺磁共振波谱分析结果表明，SO4−·和·OH均有助于PFOA的分解。据认为，PFOA 的降解是通过 SO4−• 引发的脱羧反应发生的，然后是•OH 辅助的 HF 消除过程，产生单 CF2 单元缩短的全氟烷基羧酸（PFCA，Cn−1F2n−1COOH）。脱羧和 HF 消除过程将重复进行，并最终导致所有 PFCA 完全矿化。
Perfluorooctanoic acid (PFOA) is an emerging contaminant of concern due to its toxicity for human health and ecosystems. However, successful degradation of PFOA in aqueous solutions with a cost-effective method remains a challenge, especially for groundwater. In this study, the degradation of PFOA using activated persulfate under mild conditions was investigated. The impact of different factors on persulfate activity, including pH, temperature (25 °C–50 °C), persulfate dosage and reaction time, was evaluated under different experimental conditions. Contrary to the traditional alkaline-activated persulfate oxidation, it was found that PFOA can be effectively degraded using activated persulfate under acidic conditions, with the degradation kinetics following the pseudo-first-order decay model. Higher temperature, higher persulfate dosage and increased reaction time generally result in higher PFOA degradation efficiency. Experimental results show that a PFOA degradation efficiency of 89.9% can be achieved by activated persulfate at pH of 2.0, with the reaction temperature of 50 °C, molar ratio of PFOA to persulfate as 1:100, and a reaction time of 100 h. The corresponding defluorination ratio under these conditions was 23.9%, indicating that not all PFOA decomposed via fluorine removal. The electron paramagnetic resonance spectrometer analysis results indicate that both SO4−• and •OH contribute to the decomposition of PFOA. It is proposed that PFOA degradation occurs via a decarboxylation reaction triggered by SO4−•, followed by a HF elimination process aided by •OH, which produces one-CF2-unit-shortened perfluoroalkyl carboxylic acids (PFCAs, Cn−1F2n−1COOH). The decarboxylation and HF elimination processes would repeat and eventually lead to the complete mineralization all PFCAs.