Removal of typical PFAS from water by covalent organic frameworks with different pore sizes

Wei Wang; Ye Jia; Shuangxi Zhou; Shubo Deng

doi:10.1016/j.jhazmat.2023.132522

Removal of typical PFAS from water by covalent organic frameworks with different pore sizes

J Hazard Mater. 2023 Oct 15:460:132522. doi: 10.1016/j.jhazmat.2023.132522. Epub 2023 Sep 9.

Authors

Wei Wang¹, Ye Jia², Shuangxi Zhou², Shubo Deng³

Affiliations

¹ 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.
² State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xi'ning, Qinghai Province 810016, China.
³ 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. Electronic address: dengshubo@tsinghua.edu.cn.

PMID: 37708647
DOI: 10.1016/j.jhazmat.2023.132522

Abstract

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.

Keywords: Adsorption mechanism; Covalent organic frameworks; Nanobubbles; PFAS length; Pore size.