Abstract In this study we examined whether a Gram-positive and a Gram-negative bacterial species have the capability to remove perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) from solution through sorption reactions under two different pH conditions. We developed a novel approach for quantifying PFAS in solution using particle-induced gamma-ray emission (PIGE) spectroscopy, and we used the results to constrain the important PFAS-bacterial sorption mechanisms. A mass balance experiment measuring PFOS in the aqueous phase and solid phase confirmed that PIGE spectroscopy measurements can account for all PFOS in the system, demonstrating for the first time how PIGE spectroscopy can be used to quantify the extent of PFAS sorption in experimental systems. Significant sorption occurred under most conditions studied, with up to 40 ± 5% and 67 ± 11% sorption of PFOA and PFOS, respectively. PFOA and PFOS sorption were both rapid, with steady-state being attained within minutes. PFOS sorption was pH dependent while PFOA sorption was pH independent, and greater sorption occurred onto Bacillus subtilis biomass compared to Pseudomonas putida biomass for both PFAS types. This sorption behavior suggests that pH, the PFAS head molecule, and cell wall structure all have a significant effect on the extent and mechanisms of bacterial sorption of PFAS. The observed sorption behaviors suggest that sorption of both molecules involves electrostatic and hydrophobic components. PFOS desorption was rapid and exhibited complete reversibility for both bacterial species, indicating that sorption is likely a cell surface phenomenon with no internalization occurring on the timescale of these experiments, and that the process can be modeled as an equilibrium reaction. Our work demonstrates that different PFAS molecules react to bacteria differently, and thus likely have markedly different mobilities in the environment. PFAS sorption in geologic systems is strongly influenced by organic matter, and our results suggest that biosorption may represent an inexpensive and effective PFAS remediation technique.

中文翻译：

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PFOS 和 PFOA 对革兰氏阳性菌和革兰氏阴性菌的吸附和解吸行为，使用粒子诱导伽马射线发射 (PIGE) 光谱法测量

摘要 在这项研究中，我们检查了革兰氏阳性菌和革兰氏阴性菌是否能够通过两种不同 pH 条件下的吸附反应从溶液中去除全氟辛酸 (PFOA) 和全氟辛烷磺酸 (PFOS)。我们开发了一种使用粒子诱导伽马射线发射 (PIGE) 光谱法量化溶液中 PFAS 的新方法，并使用结果来限制重要的 PFAS 细菌吸附机制。测量水相和固相中 PFOS 的质量平衡实验证实，PIGE 光谱测量可以解释系统中的所有 PFOS，首次展示了如何使用 PIGE 光谱来量化实验系统中 PFAS 的吸附程度。在研究的大多数条件下发生了显着的吸附，PFOA 和 PFOS 的吸附率分别高达 40 ± 5% 和 67 ± 11%。PFOA 和 PFOS 的吸附都很快，几分钟内即可达到稳态。PFOS 的吸附是 pH 依赖性的，而 PFOA 的吸附是 pH 无关的，与两种 PFAS 类型的恶臭假单胞菌生物质相比，枯草芽孢杆菌生物质的吸附更大。这种吸附行为表明，pH、PFAS 头部分子和细胞壁结构都对细菌吸附 PFAS 的程度和机制有显着影响。观察到的吸附行为表明两种分子的吸附都涉及静电和疏水成分。PFOS 解吸速度很快，并且对两种细菌都表现出完全可逆性，表明吸附可能是细胞表面现象，在这些实验的时间尺度上没有发生内化，并且该过程可以建模为平衡反应。我们的工作表明，不同的 PFAS 分子对细菌的反应不同，因此在环境中可能具有明显不同的迁移率。地质系统中的 PFAS 吸附受有机物质的强烈影响，我们的结果表明，生物吸附可能代表了一种廉价且有效的 PFAS 修复技术。