Removal of per- and polyfluoroalkyl substances by activated hydrochar derived from food waste: Sorption performance and desorption hysteresis

Fan Chen; Jiangliang Chen; Xuemei Liu; Yue Zhi; Shenhua Qian; Wei Li; Xiaoming Wang

doi:10.1016/j.envpol.2023.122820

Removal of per- and polyfluoroalkyl substances by activated hydrochar derived from food waste: Sorption performance and desorption hysteresis

Environ Pollut. 2023 Oct 27:122820. doi: 10.1016/j.envpol.2023.122820. Online ahead of print.

Authors

Fan Chen¹, Jiangliang Chen², Xuemei Liu², Yue Zhi³, Shenhua Qian³, Wei Li³, Xiaoming Wang⁴

Affiliations

¹ College of Environment and Ecology, Chongqing University, Chongqing, 400044, China. Electronic address: [email protected].
² College of Environment and Ecology, Chongqing University, Chongqing, 400044, China.
³ College of Environment and Ecology, Chongqing University, Chongqing, 400044, China; Key Laboratory of Three Gorges Reservoir Region's Eco-Environment Under Ministry of Education, Chongqing University, Chongqing, 400044, China.
⁴ College of Environment and Ecology, Chongqing University, Chongqing, 400044, China; Key Laboratory of Three Gorges Reservoir Region's Eco-Environment Under Ministry of Education, Chongqing University, Chongqing, 400044, China. Electronic address: [email protected].

PMID: 39491159
DOI: 10.1016/j.envpol.2023.122820

Abstract

Carbonaceous materials, derived from waste biomass, have proven to be a viable and appealing alternative for removing emerging micro-pollutants, such as per- and polyfluoroalkyl substances (PFAS). To assess the feasibility and efficacy of using material derived from food waste to alleviate PFAS pollution, this study prepared activated hydrochar (AHC) for sorbing ten PFAS, including five perfluoroalkyl carboxylic acids (PFCA; C4-C8), three perfluoroalkyl sulfonic acids (PFSA; C4, C6, C8), and two emerging PFAS, namely hexafluoropropylene oxide dimer acid (commercial name GenX, an alternative to perfluorooctanoic acid (PFOA)) and 6:2 fluorotelomer sulfonic acid (6:2 FTS). The results demonstrated that AHC possessed a relatively high specific surface area (207 m²/g) and hydrophobic surface properties. At environmentally relevant concentrations (40 μg/L), the sorption partition coefficients (log K_d) of PFAS on AHC ranged from 2.33 to 6.49 L/kg. Notably, GenX exhibited a lower log K_d value (2.33 L/kg) than PFOA (3.88 L/kg). The AHC showed favorable sorption performance for all tested PFAS, with log K_d values surpassing other reported sorbents (e.g., 0.83 for GenX on pyrochar, and 2.83 for PFOA on commercial biochar). Additionally, desorption hysteresis was observed for all PFAS, except for PFOA, and was particularly pronounced in PFBA, GenX, and 6:2 FTS at high initial concentrations, with Hysteresis Index (HI) values varying from 0.31 to 1.45, 0.68 to 1.88, and 0.51 to 1.85, respectively. Given its robust sorption capacity and desorption hysteresis toward PFAS, AHC is expected to be a favorable candidate for remediating PFAS-contaminated water. This study underscores, for the first time, the potential of food waste-derived hydrochar as an efficient sorbent for alleviating PFAS contamination, and further study is needed to investigate the sorption and desorption behaviors of PFAS on AHC at various environmental conditions.

Keywords: 6:2 FTS; Desorption hysteresis; GenX; Hydrothermal carbonization; PFAS.