The influence of nitrogen-containing functional groups and pore structure on the adsorption of per- and polyfluoroalkyl substances in ultrapure and real water

Abstract

Activated carbon adsorption has been identified as an effective technique for per- and polyfluoroalkyl substances (PFAS) removal. However, the role of nitrogen-containing functional groups and pore size on PFAS elimination is uncertain. Therefore, this study prepared a series of AC with different nitrogen groups and pore structures by thermal treatment with urea under different temperatures (denoted as AC400, AC600 and AC800). Their PFAS adsorption performance in ultrapure and real water were investigated to identify the contribution of different nitrogen groups and pore structures. The adsorption experiment indicated that the modified AC800 with high proportion of pyridine nitrogen and medium pore volume achieved the best performance in ultrapure water due to the electrostatic interaction. However, in the real water contained dissolved organic matter (DOM), rather than AC800, AC600 with large mesopore volume exhibited the maximum adsorption capacity and kinetic due to its better inhabitation of pore blockage by DOM. It could be inferred that the electrostatic attraction force was more important in PFAS adsorption in ultrapure water, but in real water the mesopore volume was more critical due to the pore blockage by DOM. This study can provide guidance and implications for selection and development of future PFAS adsorption carbon-based material.