College of Environment, Hohai University, Nanjing, 210098, PR China; Ministry of Education Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Hohai University, Nanjing 210098, PR China.
College of Environment, Hohai University, Nanjing, 210098, PR China; Ministry of Education Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Hohai University, Nanjing 210098, PR China.
Chemosphere. 2022 Dec;309(Pt 1):136733. doi: 10.1016/j.chemosphere.2022.136733. Epub 2022 Oct 6.
The safety threat posed by Perfluoroalkyl acids (PFAAs) in drinking water is a growing concern. In this study, we loaded chitosan (CS) on granular activated carbon (GAC) to adsorb PFAAs, and we explored the role of nanobubbles in the adsorption process through experiments and density functional theory (DFT) calculations. Compared with GAC, we found that the use of the composite adsorbent (CS/GAC) enhanced the removal rate of perfluorooctanoic acid by 136% with the assistance of nanobubbles. PFAAs with different chain lengths have different adsorption mechanisms owing to surface activity differences. PFAAs with longer C-F chains can be directly enriched with amino groups on the CS or air-water interface on composite adsorbents. Additionally, PFAAs can be enriched with nanobubbles in solution to form nanobubble-PFAA colloids, which are adsorbed by protonated amino groups on CS through electrostatic interactions. We found that PFAAs with shorter C-F chains are less affected by nanobubbles, and DFT calculations indicated that the adsorption of short-chain PFAAs is mainly affected by electrostatic interactions. We also proved that the electrostatic interactions between CS and PFAAs are mainly derived from the abundant protonated amino groups.
饮用水中全氟烷基酸 (PFAAs) 带来的安全威胁日益受到关注。在这项研究中，我们将壳聚糖 (CS) 负载到颗粒活性炭 (GAC) 上以吸附 PFAAs，并通过实验和密度泛函理论 (DFT) 计算探索了纳米气泡在吸附过程中的作用。与 GAC 相比，我们发现复合吸附剂 (CS/GAC) 在纳米气泡的辅助下，将全氟辛酸的去除率提高了 136%。由于表面活性的差异，不同链长的 PFAAs 具有不同的吸附机制。具有较长 C-F 链的 PFAAs 可以直接在复合吸附剂上的 CS 或气-水界面上被氨基富集。此外，PFAAs 可以在溶液中被纳米气泡富集，形成纳米气泡-PFAA 胶体，通过静电相互作用被 CS 上的质子化氨基吸附。我们发现，具有较短 C-F 链的 PFAAs 受纳米气泡的影响较小，DFT 计算表明，短链 PFAAs 的吸附主要受静电相互作用的影响。我们还证明了 CS 和 PFAAs 之间的静电相互作用主要来自于丰富的质子化氨基。
