Contribution of Nanobubbles for PFAS Adsorption on Graphene and OH- and NH2-Functionalized Graphene: Comparing Simulations with Experimental Results
Contribution of Nanobubbles for PFAS Adsorption on Graphene and OH- and NH2-Functionalized Graphene: Comparing Simulations with Experimental Results
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DOI：
10.1021/acs.est.1c03022
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发表时间：
2021-09-24
影响因子：
11.4
通讯作者：
Deng, Shubo
中科院分区：
文献类型：
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作者：
Jiang, Xiangzhe;Wang, Wei;Deng, Shubo
全氟烷基和多氟烷基物质（PFAS）普遍存在于世界各地的水生环境中。近年来，有人提出PFAS在吸附剂上纳米气泡表面的富集，但没有直接证据支持这种新的吸附机制。在这项研究中，我们使用密度泛函理论（DFT）和分子动力学（MD）模拟研究的原始和功能化的石墨烯（GR）上的PFAS吸附的纳米气泡的贡献。PFAS在GR-NH 2上的吸附能高于GR-OH，而GR的吸附能最低。当考虑水分子的影响时，非极性GR对PFAS的吸附不受疏水作用的影响。在纳米气泡存在下，GR和GR-NH 2均能有效去除PFAS，但两者的吸附机理不同。对于疏水性GR，最初附着在材料表面的纳米气泡起主要作用，而对于亲水性GR-NH 2，分散在溶液中的纳米气泡更重要。此外，纳米气泡对长链PFAS有更显著的贡献。我们的脱气和曝气实验可以支持模拟结果。除气后PFOS去除率最大下降27.7%，曝气后PFOS去除率最大上升21.0%~ 29.2%。该研究可为PFAS在固液界面的环境过程和污染控制提供理论依据。
Per- and polyfluoroalkyl substances (PFAS) are ubiquitous in aquatic environments around the world. In recent years, the enrichment of PFAS on the surface of nanobubbles on adsorbents has been proposed, but no direct evidence has been provided to support this new adsorption mechanism. In this study, we used density functional theory (DFT) and molecular dynamics (MD) to simulatively investigate the contribution of nanobubbles for PFAS adsorption on the pristine and functionalized graphene (GR). The adsorption energy of PFAS on GR-NH2 was higher than that of GR-OH, while GR showed the lowest adsorption energy. When the effect of water molecules was considered, the oleophobic property of the C-F chain made it difficult for hydrophobic interaction to be involved in the adsorption of PFAS on nonpolar GR. With the existence of nanobubbles, both GR and GR-NH2 can effectively remove PFAS, but their adsorption mechanisms were quite different. For hydrophobic GR, the nanobubbles initially attached to the surface of materials played a major role, while for hydrophilic GR-NH2, the nanobubbles dispersed in the solution were more important. Moreover, the nanobubbles had a more significant contribution to long-chain PFAS. Our degassing and aeration experiments could support the simulation results. The removal of PFOS decreased by 27.7% at maximum after degassing and increased by 21.0%-29.2% after aeration. The study could provide a theoretical basis for the environmental process and contamination control of PFAS at the solid-liquid interfaces.