典型水环境因素对聚酯微塑料沉降的影响机制研究

以聚酯（聚对苯二甲酸乙二醇酯，简称PET）微塑料为主要对象，研究电解质浓度，电解质类型及pH值等典型水环境因素对其沉降行为的影响机制.结果表明：水环境中PET微塑料的沉降随电解质浓度的升高而不断增强，其悬液标准化浓度（C/C₀）最低可降至0.64；同一类型电解质对水环境中PET微塑料沉降行为的影响程度相似，而与1-1型电解质（NaCl及KCl）相比，水环境中1-2型电解质（CaCl₂及MgCl₂）的存在能够显著促进PET微塑料的沉降；水环境中PET微塑料的沉降随pH值的增加而降低，随着pH值由10降至4，PET微塑料悬液的C/C₀由最高0.98下降至最高0.76.一阶动力学沉降模型能够较好的拟合水环境中PET微塑料的沉降行为.此外，DLVO （Derjaguin-Landau-Verwey-Overbeek）理论能够反映出PET微塑料沉降行为的变化趋势，其计算结果与实验结果吻合度较高.本研究结果有助于提高对微塑料环境行为的认识程度，同时能够为评估微塑料环境风险提供理论依据.

Effect mechanism of aquatic environmental factor on the sedimentation of polyethylene terephthalate microplastic

In this study, the sedimentation behaviors of polyethylene terephthalate (PET) microplastic in aquatic environment were investigated under various electrolyte concentration, electrolyte type, and pH conditions. The results indicated that PET microplastic sedimentation was significantly enhanced with electrolyte concentration, and the minimum standardized concentration (C/C₀) was 0.64. The similar electrolytes showed similar impacts on PET microplastic sedimentation. However, compared with 1-1electrolytes (e.g. NaCl and KCl), the 1-2electrolytes (e.g. CaCl₂ and MgCl₂) remarkably improved PET microplastic sedimentation. PET microplastic sedimentation in aquatic environment was enhanced with decreasing pH. When pH values decreased from 10 to 4, the maximum C/C₀ of PET microplastic suspension decreased from 0.98 to 0.76. The one-site kinetic settlement model well described PET microplastic sedimentation in aquatic environment. The tendency of DLVO results was consistent with the experimental results, which may reflect the sedimentation behaviors of PET microplastic. Findings from this work were useful on improving current knowledge of microplastic environmental behaviors and providing theoretical basis for environmental risk evaluation of microplastic.