School of Chemistry, Sun Yat-sen University, Guangdong, Guangzhou, 510275, China; Guangdong Key Laboratory of Agro-environmental Pollution Control and Management, Guangdong Institute of Eco-environmental Science & Technology, Guangdong, Guangzhou, 510650, China.
Instrumental Analysis and Research Center, Sun Yat-sen University, Guangdong, Guangzhou, 510275, China.
Ecotoxicol Environ Saf. 2020 Jul 15;198:110658. doi: 10.1016/j.ecoenv.2020.110658. Epub 2020 Apr 24.
Microplastics and dissolved organic matter (DOM) are ubiquitous in aquatic environments. The adsorption behavior of DOM on microplastics in aquatic environments is a prominent concern. In this study, the adsorption of two types of DOM, Suwannee River Humic Acid (HA) and Suwannee River Fulvic Acid (FA), on polystyrene microplastics (PSMPs, 10 μm) in aquatic environments was investigated. The adsorption of both HA and FA on PSMPs could be well described by using pseudo second-order and Freundlich models. The adsorption of HA and FA on PSMPs was low pH-dependent, particularly for FA adsorption. However, the elevated ionic strength slightly increased the adsorption of HA and FA on PSMPs. Based on Freundlich model, the site energy distribution of HA and FA adsorption on PSMPs under the experimental conditions were estimated. HA and FA first occupied the high-energy adsorption sites and then diffused to the low-energy adsorption sites on PSMPs. With higher site energies, HA demonstrated a much stronger adsorption affinity to PSMPs than FA. The adsorption site heterogeneity (σ*) on PSMPs under the experimental conditions were close. Hydrophobic interaction and π-π electron donor acceptor interaction acted simultaneously in the HA and FA adsorption on PSMPs. The results of this study suggested that the environmental behaviors of microplastics would be influenced by the amount and the type of DOM as well as solution chemistry.
微塑料和溶解有机质（DOM）在水生环境中普遍存在。DOM 在水生环境中对微塑料的吸附行为是一个突出的关注点。在这项研究中，研究了两种类型的 DOM，苏万尼河腐殖酸（HA）和苏万尼河富里酸（FA）在水生环境中对聚苯乙烯微塑料（PSMPs，10 μm）的吸附。HA 和 FA 对 PSMPs 的吸附均可用准二级和 Freundlich 模型很好地描述。HA 和 FA 对 PSMPs 的吸附受 pH 值影响较小，而 FA 的吸附受 pH 值影响较大。然而，升高的离子强度略微增加了 HA 和 FA 对 PSMPs 的吸附。根据 Freundlich 模型，在实验条件下，估算了 HA 和 FA 在 PSMPs 上的吸附位能分布。HA 和 FA 首先占据高能吸附位，然后扩散到 PSMPs 上的低能吸附位。具有较高位能的 HA 对 PSMPs 的吸附亲和力远强于 FA。在实验条件下，PSMPs 上的吸附位非均质性（σ*）接近。疏水相互作用和π-π电子供体-受体相互作用同时作用于 HA 和 FA 在 PSMPs 上的吸附。本研究结果表明，微塑料的环境行为将受到 DOM 的数量和类型以及溶液化学性质的影响。
