What is it about?

The global ecological crisis of per- and polyfluoroalkyl substances (PFASs) in drinking water has gradually shifted from long-chain to short-chain PFASs; however, the widespread established PFAS adsorption technology cannot cope with the impact of such hydrophilic pollutants given the inherent defects of solid‒liquid mass transfer. Herein, we describe a reagent-free and low-cost strategy to reduce the energy state of short-chain PFASs in hydrophobic nanopores by in-situ constructing confined water structure in activated carbon (AC). Through direct (driving force) and indirect (assisted slip) effects, the confined water introduced an unprecedented dual-drive mode in the confined water-encapsulated AC (CW-AC) and completely eliminated the mass transfer barrier (3.27-5.66 kcal/mol), which caused the CW-AC to exhibit the highest adsorption capacity for various short-chain PFAS (chain length: C4-C6, functional group: -COOH or -SO3H) among parent AC and other adsorbents reported. Meanwhile, benefiting from the chain length- and functional group-dependent confined water binding pattern, the affinity of the CW-AC surpassed the traditional hydrophobicity dominance and shifted toward hydrophilic short-chain PFAS that easily escaped treatment. Importantly, the ability of CW-AC functionality to directly transfer to existing adsorption devices was verified, which could treat 21000 bed volumes of environment-related high-load (~350 ng/L short-chain PFAS each) real drinking water to below the World Health Organization’s standard. Overall, our results provide a green and cost-effective in-situ upgrade scheme for existing adsorption devices to address the short-chain PFAS crisis.

Featured Image

Why is it important?

Adsorption is the most established method used to block human exposure through drinking water to the notorious per- and polyfluoroalkyl substances (PFASs), yet is challenged by the increasing short-chain PFAS crisis due to the inherent defects of solid‒liquid mass transfer. Herein, by assembling the confined water structure in-situ in hydrophobic nanopores, we introduce an unprecedented dual-drive mode in the activated carbon to completely eliminate the mass transfer barrier and dramatically enhance its adsorption performance for various short-chain PFASs. Significantly, the methodology demonstrated is a potential in-situ upgrade of existing adsorption devices. This work will thus revolutionize the understanding of the role of confined water in mass transfer and enable an in-situ solution for the short-chain PFASs crisis in drinking water.

Read the Original

This page is a summary of: Confined water–encapsulated activated carbon for capturing short-chain perfluoroalkyl and polyfluoroalkyl substances from drinking water, Proceedings of the National Academy of Sciences, June 2023, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2219179120.
You can read the full text:



The following have contributed to this page