TY - JOUR
T1 - Retention and transport of PFOA and its fluorinated substitute, GenX, through water-saturated soil columns
AU - Liu, Guanhong
AU - Usman, Muhammad
AU - Luo, Tao
AU - Biard, Pierre François
AU - Lin, Kuangfei
AU - Greenwell, H. Chris
AU - Hanna, Khalil
N1 - Publisher Copyright:
© 2023 Elsevier Ltd
PY - 2023/11/15
Y1 - 2023/11/15
N2 - Perfluoro-2-propoxypropanoic acid (GenX) has emerged as a substitute for perfluorooctanoic acid (PFOA) especially since PFOA was listed among the persistent organic pollutants (POPs) by the Stockholm Convention in 2019. However, limited knowledge exists regarding the behavior and mobility of GenX in natural soils hindering the prediction of its environmental fate. This study investigated the mobility and retention of GenX and PFOA in soils under batch and water-saturated flow-through conditions. Batch experiments revealed that GenX has a lower binding affinity to soil than longer-chained PFOA, potentially threatening groundwater resources. Unlike metal-oxides/minerals (ferrihydrite, gibbsite and manganese dioxide), biochar (BC) and activated carbon (AC) amendments significantly enhanced the sorption of both GenX and PFOA in soil. Sorption data on minerals and carbonaceous materials implied that for shorter-chained GenX, the predominant mode of sorption was through electrostatic (ionic) interactions, while for longer-chained PFOA, hydrophobic interactions became progressively more important with increasing chain length. The dynamic flow experiments demonstrated that these soil amendments enhanced the retention of both compounds, thereby decreasing their mobility. Simultaneous injection of both compounds into columns pre-loaded with either PFOA or GenX increased their retardation. GenX sorption was more affected by pre-sorbed PFOA compared to the minimal impact of pre-loaded GenX on PFOA sorption. A newly developed reactive transport model, which incorporates a two-site sorption model and accounts for kinetic-limited processes, accurately predicted the sorption and transport of both compounds in single and binary contamination systems. These findings have important implications for predicting and assessing the fate and mobility of per- and polyfluoroalkyl substances (PFAS) in soils and groundwaters.
AB - Perfluoro-2-propoxypropanoic acid (GenX) has emerged as a substitute for perfluorooctanoic acid (PFOA) especially since PFOA was listed among the persistent organic pollutants (POPs) by the Stockholm Convention in 2019. However, limited knowledge exists regarding the behavior and mobility of GenX in natural soils hindering the prediction of its environmental fate. This study investigated the mobility and retention of GenX and PFOA in soils under batch and water-saturated flow-through conditions. Batch experiments revealed that GenX has a lower binding affinity to soil than longer-chained PFOA, potentially threatening groundwater resources. Unlike metal-oxides/minerals (ferrihydrite, gibbsite and manganese dioxide), biochar (BC) and activated carbon (AC) amendments significantly enhanced the sorption of both GenX and PFOA in soil. Sorption data on minerals and carbonaceous materials implied that for shorter-chained GenX, the predominant mode of sorption was through electrostatic (ionic) interactions, while for longer-chained PFOA, hydrophobic interactions became progressively more important with increasing chain length. The dynamic flow experiments demonstrated that these soil amendments enhanced the retention of both compounds, thereby decreasing their mobility. Simultaneous injection of both compounds into columns pre-loaded with either PFOA or GenX increased their retardation. GenX sorption was more affected by pre-sorbed PFOA compared to the minimal impact of pre-loaded GenX on PFOA sorption. A newly developed reactive transport model, which incorporates a two-site sorption model and accounts for kinetic-limited processes, accurately predicted the sorption and transport of both compounds in single and binary contamination systems. These findings have important implications for predicting and assessing the fate and mobility of per- and polyfluoroalkyl substances (PFAS) in soils and groundwaters.
KW - Groundwater
KW - Mobility
KW - Modeling
KW - PFAS
KW - Soil
KW - Water
KW - Fluorocarbons/analysis
KW - Soil/chemistry
KW - Caprylates/chemistry
KW - Minerals
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UR - http://www.scopus.com/inward/citedby.url?scp=85171346482&partnerID=8YFLogxK
UR - https://www.mendeley.com/catalogue/9634810a-4f78-3104-b411-bd232fe8bb45/
U2 - 10.1016/j.envpol.2023.122530
DO - 10.1016/j.envpol.2023.122530
M3 - Article
C2 - 37690470
AN - SCOPUS:85171346482
SN - 0269-7491
VL - 337
SP - 122530
JO - Environmental Pollution
JF - Environmental Pollution
M1 - 122530
ER -