Stults John F, Choi Youn Jeong, Rockwell Cooper, Schaefer Charles E, Nguyen Dung D, Knappe Detlef R U, Illangasekare Tissa H, Higgins Christopher P
Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado 80401, United States.
CDM Smith, 14432 SE Eastgate Way Suite 100, Bellevue, Washington 98007, United States.
Environ Sci Technol. 2023 Apr 4;57(13):5203-5215. doi: 10.1021/acs.est.2c07316. Epub 2023 Mar 24.
Air-water interfacial retention of poly- and perfluoroalkyl substances (PFASs) is increasingly recognized as an important environmental process. Herein, column transport experiments were used to measure air-water interfacial partitioning values for several perfluoroalkyl ethers and for PFASs derived from aqueous film-forming foam, while batch experiments were used to determine equilibrium data for compounds exhibiting evidence of rate-limited partitioning. Experimental results suggest a Freundlich isotherm best describes PFAS air-water partitioning at environmentally relevant concentrations (10-10 ng/L). A multiparameter regression analysis for prediction was performed for the 15 PFASs for which equilibrium values were determined, assessing 246 possible combinations of 8 physicochemical and system properties. Quantitative structure-property relationships (QSPRs) based on three to four parameters provided predictions of high accuracy without model overparameterization. Two QSPRs ( values of 0.92 and 0.83) were developed using an assumed average Freundlich value of 0.65 and validated across a range of relevant concentrations for perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA), and hexafluoropropylene oxide-dimer acid (i.e., GenX). A mass action model was further modified to account for the changing ionic strength on PFAS air-water interfacial sorption. The final result was two distinct QSPRs for estimating PFAS air-water interfacial partitioning across a range of aqueous concentrations and ionic strengths.
多氟烷基和全氟烷基物质（PFASs）在气-水界面的滞留现象日益被视为一个重要的环境过程。在此，采用柱传输实验来测量几种全氟烷基醚以及水成膜泡沫衍生的PFASs的气-水界面分配值，同时采用批次实验来确定显示出有限分配速率证据的化合物的平衡数据。实验结果表明，Freundlich等温线最能描述环境相关浓度（10⁻¹⁰ ng/L）下PFASs的气-水分配情况。对已确定平衡值的15种PFASs进行了预测的多参数回归分析，评估了8种物理化学和系统性质的246种可能组合。基于三到四个参数的定量结构-性质关系（QSPRs）提供了高精度的预测，且没有模型过度参数化的问题。使用假设的平均Freundlich值0.65开发了两个QSPRs（值分别为0.92和0.83），并在一系列全氟辛烷磺酸（PFOS）、全氟辛酸（PFOA）和六氟环氧丙烷二聚酸（即GenX）的相关浓度范围内进行了验证。进一步修改了质量作用模型，以考虑离子强度变化对PFASs气-水界面吸附的影响。最终结果是得到了两个不同的QSPRs，用于估计一系列水浓度和离子强度下PFASs的气-水界面分配情况。
