亲水性有机化合物和微塑料(MPs)在环境中的广泛共存极大地增加了它们相关的环境问题。为评价含氧MPs对共存污染物的潜在载体效应,四种亲水性有机化合物(苯甲酸,磺胺甲恶唑,在水生环境中研究了磺胺erazine和环丙沙星)对MPs(原始和风化聚酰胺(PA))的影响。结果表明,表面形貌,尺寸,氧含量,分子结构,风化后PA的表面电荷和结晶度发生变化,热活化过硫酸钾处理的PA的风化程度最高。主要的吸附机制包括氢键,疏水相互作用,电荷辅助氢键,和静电相互作用。氢键和疏水相互作用有助于吸附,而在特定pH条件下,静电相互作用减弱了吸附。通过pH值影响实验验证了电荷辅助氢键(CAHB)的形成,这个力可以克服静电斥力。与其他三种PA相比,由于含氧官能团的增加,同核CAHB的形成很好地解释了碱性条件下KPA(由K2S2O8风化的PA)的高吸附。此外,风化并不总是增强亲水性有机化合物在PA上的吸附,这与表面电荷的变化有关,PA的结晶度和亲水性。总的来说,物理和化学性质(例如,比表面积,氧含量,风化后PA的分子结构)及其吸附趋势与本研究中的其他无氧MPs不同。这项工作可以为MPs的环境风险提供基础数据,并有助于阐明和理解水生环境中含氧MPs的过程。
The widespread coexistence of hydrophilic organic compounds and microplastics (MPs) in the environment has greatly increased their associated environmental problems. To evaluate the potential carrier effect of oxygen-containing MPs on coexisting pollutants, adsorption behaviors of four hydrophilic organic compounds (benzoic acid, sulfamethoxazole, sulfamerazine and ciprofloxacin) on MPs (pristine and weathered polyamide (PA)) were studied in the aquatic environment. The results showed that the surface morphology, size, oxygen content, molecular structure, surface charge and crystallinity of PA were changed after weathering, and the weathering degree of PA treated with heat-activated potassium persulfate was the highest. The main adsorption mechanisms included hydrogen bonding, hydrophobic interaction, charge-assisted hydrogen bonding, and electrostatic interaction. Hydrogen bonding and hydrophobic interaction contributed to the adsorption, while electrostatic interaction weakened the adsorption under the specific pH conditions. The formation of charge-assisted hydrogen bonding (CAHB) was also verified through pH influence experiments, and this force can overcome the electrostatic repulsion. The high adsorption of KPA (PA weathered by K2S2O8) under alkaline conditions was well explained by the formation of homonuclear CAHB due to the increase of oxygen-containing functional groups compared to the other three PA. Additionally, weathering did not always enhance the adsorption of hydrophilic organic compounds on PA, which was related to the changes in surface charge, crystallinity and hydrophilicity of PA. Overall, the physical and chemical properties (e.g., specific surface area, oxygen content, molecular structure) of PA after weathering and its trend of adsorption were different from other oxygen-free MPs in this study. This work can provide basic data for environmental risk of MPs and contribute to clarify and understand the processes of oxygenated MPs in the aquatic environment.