Université de Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, ISCR-UMR 6226, F-35000, Rennes, France; State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai, 200237, China.
Université de Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, ISCR-UMR 6226, F-35000, Rennes, France.
Environ Pollut. 2023 Nov 15;337:122530. doi: 10.1016/j.envpol.2023.122530. Epub 2023 Sep 8.
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.
全氟-2-丙氧基丙酸（GenX）已成为全氟辛烷磺酸（PFOA）的替代品，尤其是 2019 年《斯德哥尔摩公约》将 PFOA 列为持久性有机污染物（POPs）之后。然而，由于 GenX 在自然土壤中的行为和迁移性知之甚少，阻碍了对其环境归宿的预测。本研究在批量和水饱和流动通过条件下研究了 GenX 和 PFOA 在土壤中的迁移和保留。批量实验表明，GenX 与土壤的结合亲和力低于长链 PFOA，可能会威胁到地下水资源。与金属氧化物/矿物质（水铁矿、三水铝石和二氧化锰）不同，生物炭（BC）和活性炭（AC）的添加显著增强了土壤中 GenX 和 PFOA 的吸附。对矿物质和含碳材料的吸附数据表明，对于较短链的 GenX，主要的吸附模式是通过静电（离子）相互作用，而对于较长链的 PFOA，随着链长的增加，疏水性相互作用变得越来越重要。动态流动实验表明，这些土壤改良剂增强了两种化合物的保留，从而降低了它们的迁移性。同时将这两种化合物注入预先加载了 PFOA 或 GenX 的柱子中会增加它们的阻滞。与预先加载的 GenX 对 PFOA 吸附的最小影响相比，预吸附的 PFOA 对 GenX 吸附的影响更大。新开发的反应传输模型，结合了双位点吸附模型，并考虑了动力学限制过程，准确预测了单一和二元污染系统中两种化合物的吸附和传输。这些发现对预测和评估全氟和多氟烷基物质（PFAS）在土壤和地下水中的归宿和迁移性具有重要意义。
