Yuan Shideng, Wang Xueyu, Jiang Zhaoli, Zhang Heng, Yuan Shiling
Key Lab of Colloid and Interface Chemistry, Shandong University, Jinan, Shandong 250100 PR China.
Key Lab of Colloid and Interface Chemistry, Shandong University, Jinan, Shandong 250100 PR China.
Water Res. 2023 Jun 1;236:119947. doi: 10.1016/j.watres.2023.119947. Epub 2023 Apr 7.
As a class of synthetic persistent organic pollutants, contamination of Per-and poly-fluoroalkyl substances (PFAS) in drinking water has attracted widespread concern. Aeration has been confirmed to enhance the removal of PFAS in drinking water by activated carbon (AC). However, the contribution of the air-water interface in removing PFAS is not yet to be fully understood at the molecular level. In this work, molecular dynamics (MD) simulations were employed to investigate the role of nanobubble in removing PFAS in the aqueous environment. The result suggests that the free energies of the air-water interface are about 3-7 kcal mol lower than that of the bulk water region, indicating that the transformation of PFAS from the water phase into the air-water interface is favorable from the viewpoint of thermodynamics. The interface-water partition coefficients (P) of PFAS are in the order of PFOS > PFOA > PFHxS > PFBS. On the air-water-AC three-phase interface, PFBS can not only move along the interface region but also leave the interface region into water phase, while PFOS tended to move along the interface region until it was captured by AC. Finally, the ΔG quantitative structure-activity relationships (QSAR) models were developed to predict the removal efficiencies of PFAS enhanced by aeration in aquatic systems. The proposed mechanism promotes the understanding of the contribution of air-water interface in removing PFAS from drinking water by activated carbon.
作为一类合成持久性有机污染物，饮用水中全氟和多氟烷基物质（PFAS）的污染已引起广泛关注。曝气已被证实可增强活性炭（AC）对饮用水中PFAS的去除效果。然而，气-水界面在去除PFAS方面的作用在分子水平上尚未得到充分理解。在这项工作中，采用分子动力学（MD）模拟来研究纳米气泡在水环境中去除PFAS的作用。结果表明，气-水界面的自由能比本体水区域低约3-7千卡/摩尔，这表明从热力学角度来看，PFAS从水相转变到气-水界面是有利的。PFAS的界面-水分配系数（P）顺序为全氟辛烷磺酸>全氟辛酸>全氟己烷磺酸>全氟丁烷磺酸。在气-水-AC三相界面上，全氟丁烷磺酸不仅可以沿着界面区域移动，还可以离开界面区域进入水相，而全氟辛烷磺酸则倾向于沿着界面区域移动，直到被活性炭捕获。最后，建立了ΔG定量构效关系（QSAR）模型，以预测曝气增强水生系统中PFAS去除效率。所提出的机制有助于理解气-水界面在活性炭去除饮用水中PFAS方面的作用。
