紫外老化微塑料衍生DOM理化特性及其与磺胺嘧啶、铜的络合机制

Characteristics of Microplastic-derived Dissolved Organic Matter(MPDOM)and the Complexation Between MPDOM and Sulfadiazine/Cu~(2+)

微塑料在老化过程中所释放的溶解性有机质(MPDOM)可与有机污染物、重金属等污染物发生络合反应,影响污染物的迁移转化.选取聚对苯二甲酸乙二醇酯(PET)和聚苯乙烯(PS)两种微塑料,利用荧光猝灭法及多种光谱分析技术和方法,同时结合Ryan-Weber模型,探究了MPDOM的光谱特性以及MPDOM与磺胺嘧啶(SDZ)、铜离子(Cu^(2+))的络合机制.紫外-可见吸收光谱分析结果表明,老化后两种MPDOM的相对分子量减小、芳香性及腐殖化程度增加,芳环上的羧基、羰基、羟基及酯类取代基增多.MPDOM与SDZ、Cu^(2+)的荧光猝灭均属于静态猝灭,猝灭后两种MPDOM的芳香性和腐殖化程度相近,相对分子质量相当.三维荧光光谱结合平行因子分析法共鉴定出两种类腐殖质组分和一种类蛋白质组分.同步荧光光谱分析结果表明,两种MPDOM均以类蛋白组分优先与SDZ发生反应,与Cu^(2+)反应时更为敏感.结合Ryan-Weber模型可知,两种猝灭体系均以类腐殖质组分与PET-DOM的结合能力更高,但总体来说SDZ猝灭体系中MPDOM的结合能力要强于Cu^(2+)体系.

Microplastic-derived dissolved organic matter(MPDOM)during the aging process could be complexed with organic pollutants,heavy metals,and other contaminants and thus affect their migration and transformation.In this study,two types of microplastics,polyethylene terephthalate(PET)and polystyrene(PS),were selected to investigate the spectral properties of MPDOM and their effect on the complexation between MPDOM and sulfadiazine(SDZ)/copper ion(Cu^(2+))using the fluorescence quenching method,various spectroscopic analysis techniques,and the Ryan-Weber quenching model.The results of UV-vis absorption spectroscopy analysis showed that the molecular weight of the two MPDOMs decreased;the aromaticity and humification increased;and the carboxyl,carbonyl,hydroxyl,and ester substituents on aromatic rings increased after aging.The fluorescence quenching process between MPDOM and SDZ/Cu^(2+)was static quenching.After quenching,the aromaticity and humification of the two MPDOMs were similar,and the molecular weights were comparable.Combined with three-dimensional fluorescence spectra and parallel factor analysis,two humic-like components and one protein-like component were identified.In addition,the protein-like components of MPDOM reacted preferentially with SDZ and were more sensitive to Cu^(2+).The results of the Ryan-Weber quenching model revealed that the binding ability of humic-like components to PET-DOM was higher in both SDZ and Cu^(2+)quenching systems,but the binding ability of MPDOM in the SDZ quenching system was generally stronger than that in the Cu^(2+)system.