盐度对全氟和多氟烷基物质(PFAS)在海水-沉积物界面吸附行为的影响

Effects of salinity on the adsorption behavior of perfluorinated and polyfluoroalkyl substances(PFAS)at the seawater-sediment interface

模拟海水-沉积物环境,分析了不同盐度影响下5种全氟和多氟烷基物质(PFAS)含量变化,并解析了PFAS的吸附动力学和热力学等吸附行为.在设置的不同盐度实验组中,全氟辛烷磺酸(PFOS)在沉积物中的吸附能力强于相同碳氟链长度的全氟辛酸(PFOA),其中PFOS在沉积物中的吸附量大于其替代物9-氯十六氟-3-氧杂壬烷-1-磺酸钾(9Cl-PF3ONS);PFOA在沉积物中的吸附量大于其替代物六氟环氧丙烷二聚酸(HFPO-DA),而小于另一替代物六氟环氧丙烷三聚酸(HFPO-TA).PFAS的沉积物分配系数(Kd)与盐度呈正相关,随着盐度的升高,PFAS在沉积物中的吸附量随之增加.PFAS的吸附过程涉及了疏水和静电相互作用.

In order to understand adsorption kinetics and thermodynamics of per-and polyfluoroalkyl substances(PEAS),the five PFAS components were detected in the simulated seawater-sediment environments in this study.The adsorption capacity of perfluorooctane sulfonic acid(PFOS)under varying salinity conditions was found to be greater than that of perfluorooctanoic acid(PFOA)with the same carbon-fluorine chain length.The equilibrium adsorption capacity of PFOS in sediments was observed to be higher than that of its alternative,potassium 9-chlorohexadecafluoro-3-oxanonane-1-sulfonate(9Cl-PF3ONS);and the equilibrium adsorption capacity of PFOA in sediments was greater than that of its alternative,hexafluoropropylene oxide dimeric acid(HFPO-DA),but lower than another alternative,hexafluoropropylene oxide trimeric acid(HFPO-TA).A strong positive correlation was observed between the Kd values of PFAS and salinity levels.The sorption of PFAS onto sediments exhibited an upward trend as the salt concentration increased.The adsorption mechanism of PFAS involved both hydrophobic interactions and electrostatic interactions.