Wang Wei, Jia Ye, Zhou Shuangxi, Deng Shubo
State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xi'ning, Qinghai Province 810016, China; School of Environment, Beijing Key Laboratory for Emerging Organic Contaminants Control, State Key Joint Laboratory of Environment Simulation and Pollution Control (SKLESPC), Tsinghua University, Beijing 100084, China.
State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xi'ning, Qinghai Province 810016, China.
J Hazard Mater. 2023 Oct 15;460:132522. doi: 10.1016/j.jhazmat.2023.132522. Epub 2023 Sep 9.
Adsorption is highly effective and desirable for the removal of per- and polyfluoroalkyl substances (PFAS) from water, and suitable pore size of porous adsorbents is important for efficient removal of PFAS, but the relationship between adsorbent pore size and PFAS adsorption remains unclear. In this study, five regular covalent organic frameworks (COFs) with distinct pore sizes were successfully synthesized, and the correlation between the pore size of COFs and PFAS length for efficient PFAS adsorption was investigated. Both excessively small and large pore sizes of COFs are not conducive to the efficient adsorption of PFAS due to the diffusion hindrance and weak binding forces. The COFs with a pore size ranging from 2.5 to 4.0 times of the PFAS molecular size demonstrated the most suitable for PFAS adsorption. This study also investigated the potential impact of nanobubbles on PFAS adsorption on orderly porous COFs through aeration and degassing treatment of the adsorption system. The bubbles on hydrophobic COFs were verified to be responsible for PFAS adsorption, another important adsorption mechanism of PFAS on COFs. The long-chain PFAS have stronger enrichment at the gas-liquid interface than the short-chain PFAS, resulting in higher adsorption capacity for long-chain PFAS.
吸附对于从水中去除全氟和多氟烷基物质（PFAS）非常有效且值得期待，并且多孔吸附剂的合适孔径对于高效去除PFAS很重要，但吸附剂孔径与PFAS吸附之间的关系仍不清楚。在本研究中，成功合成了五种具有不同孔径的规则共价有机框架（COF），并研究了COF孔径与PFAS长度之间对于高效PFAS吸附的相关性。由于扩散阻碍和弱结合力，COF过小和过大的孔径都不利于PFAS的高效吸附。孔径为PFAS分子大小2.5至4.0倍的COF显示出最适合PFAS吸附。本研究还通过对吸附系统进行曝气和脱气处理，研究了纳米气泡对PFAS在有序多孔COF上吸附的潜在影响。疏水性COF上的气泡被证实是PFAS吸附的原因，这是PFAS在COF上的另一种重要吸附机制。长链PFAS在气液界面的富集比短链PFAS更强，导致长链PFAS的吸附容量更高。
