Salawu Omobayo A, Olivares Christopher I, Adeleye Adeyemi S
Department of Civil and Environmental Engineering, University of California, Irvine, CA 92697-2175, USA; The Water-Energy Nexus Centre, University of California, Irvine, CA 92697-2175, USA.
Department of Civil and Environmental Engineering, University of California, Irvine, CA 92697-2175, USA; The Water-Energy Nexus Centre, University of California, Irvine, CA 92697-2175, USA; Department of Earth and Environmental Engineering, Columbia University, New York, NY 10027-6623, United States.
J Hazard Mater. 2024 May 15;470:134185. doi: 10.1016/j.jhazmat.2024.134185. Epub 2024 Mar 31.
Microplastics (MPs) are abundant in aquatic systems. The ecological risks of MPs may arise from their physical features, chemical properties, and/or their ability to concentrate and transport other contaminants, such as per- and polyfluoroalkyl substances (PFAS). PFAS have been extracted from MPs found in natural waters. Still, there needs to be a mechanistic investigation of the effect of PFAS chemistry and water physicochemical properties on how PFAS partition onto secondary MPs. Here, we studied the influence of pH, natural organic matter (NOM), ionic strength, and temperature on the adsorption of PFAS on MPs generated from PET water bottles. The adsorption of PFAS to the MPs was thermodynamically spontaneous at 25 °C, based on Gibb's free energy (ΔG = -16 to -23 kJ/mol), primarily due to increased entropy after adsorption. Adsorption reached equilibrium within 7-9 h. Hence, PFAS will partition to the surface of secondary PET MPs within hours in fresh and saline waters. Natural organic matter decreased the capacity of secondary PET MPs for PFAS through electrosteric repulsion, while higher ionic strength favored PFAS adsorption by decreasing electrostatic repulsion. Increased pH increased electrostatic repulsion, which negated PFAS adsorption. The study provides fundamental information for developing models to predict interactions between secondary MPs and PFAS.
微塑料（MPs）在水生系统中大量存在。微塑料的生态风险可能源于其物理特征、化学性质和/或其浓缩和运输其他污染物的能力，例如全氟和多氟烷基物质（PFAS）。已从天然水体中发现的微塑料中提取出全氟和多氟烷基物质。然而，仍需要对全氟和多氟烷基物质的化学性质以及水的物理化学性质对全氟和多氟烷基物质在次生微塑料上的分配方式的影响进行机理研究。在此，我们研究了pH值、天然有机物（NOM）、离子强度和温度对全氟和多氟烷基物质在PET水瓶产生的微塑料上吸附的影响。根据吉布斯自由能（ΔG = -16至-23 kJ/mol），在25°C下，全氟和多氟烷基物质在微塑料上的吸附在热力学上是自发的，这主要是由于吸附后熵增加。吸附在7-9小时内达到平衡。因此，在淡水和盐水中，全氟和多氟烷基物质将在数小时内分配到次生PET微塑料的表面。天然有机物通过电空间排斥作用降低了次生PET微塑料对全氟和多氟烷基物质的吸附能力，而较高的离子强度通过减少静电排斥作用有利于全氟和多氟烷基物质的吸附。pH值升高会增加静电排斥作用，从而抵消全氟和多氟烷基物质的吸附。该研究为开发预测次生微塑料与全氟和多氟烷基物质之间相互作用的模型提供了基础信息。
