ABSTRACT

Microplastics (MPs) and pesticides are two classes of environmental pollutants and have become global challenges. MPs could adsorb substantial environmental pollutants, which may affect their transportation, distribution and cause combination toxicity. Therefore, the study of sorption properties and mechanisms is the basis of the ecological risk assessment of co-exposure of pesticides and MPs. In this research, typical triazole fungicide tebuconazole (TEB) is selected as a model pollutant, and its sorption behavior was investigated by kinetic and isotherm models. Meanwhile, a series of environmental influencing factors, like pH, salinity, and metals were conducted. Results showed that the sorption of TEB on MPs could reach equilibrium at 24 h, and the sorption capacity followed the order of PA (polyamide) > PS (polystyrene) > PP (polypropylene). The pseudo-second-order model was the most appropriate model to describe kinetic data, and the Freundlich model was well fit for PA sorption isotherms, in contrast the Langmuir model is better for PP and PS. Additionally, the pH of the solution, salinity, and metals have an important effect on sorption. Combined with Fourier Transform Infrared Spectroscopy and environmental influencing factors, the sorption mechanisms were mainly electrostatic interaction and hydrogen bond for PA and PP, and hydrophobic force, intermolecular force, and electrostatic force for PS, respectively.

摘要

微塑料（MP）和农药是两类环境污染物，已成为全球性挑战。MPs可以吸附大量的环境污染物，这可能会影响其运输、分布并引起组合毒性。因此，吸附特性和机理的研究是农药与MPs共暴露生态风险评估的基础。本研究选择典型的三唑类杀菌剂戊唑醇（TEB）作为模型污染物，通过动力学和等温线模型研究了其吸附行为。同时，对pH、盐度、金属等一系列环境影响因素进行了研究。结果表明，MPs对TEB的吸附在24 h时即可达到平衡，吸附容量大小依次为PA（聚酰胺）> PS（聚苯乙烯）> PP（聚丙烯）。拟二阶模型是描述动力学数据最合适的模型，Freundlich模型非常适合PA吸附等温线，而Langmuir模型更适合PP和PS。此外，溶液的 pH 值、盐度和金属对吸附也有重要影响。结合傅里叶变换红外光谱和环境影响因素，PA和PP的吸附机制主要为静电作用和氢键，PS的吸附机制主要为疏水力、分子间力和静电力。