不同老化条件对聚酰胺6微塑料吸附磺胺噻唑的影响

聚酰胺类微塑料(PA-MPs)和磺胺类抗生素(SAs)均为新兴污染物且已广泛检出,其中聚酰胺6微塑料由常用的聚酰胺6塑料产生,磺胺噻唑(ST)是典型的SAs。由于微塑料在环境暴露中普遍易老化,因此探究了聚酰胺6微塑料在未老化、紫外老化、紫外和H₂O₂老化(分别记为PA6、PA6-UV、PA6-UV+H₂O₂)下对ST的吸附影响。结果表明,3种聚酰胺6微塑料对ST的吸附在24.0 h内基本都达到平衡,可以用伪二级动力学模型较好地拟合(R²≥0.969),Freundlich模型能很好地描述吸附等温线(R²≥0.967)。老化降低了聚酰胺6微塑料吸附ST的能力,平衡吸附量为PA6>PA6-UV>PA6-UV+H₂O₂。pH、盐度和溶解有机质(DOM)对聚酰胺6微塑料吸附ST有不同的影响。老化后聚酰胺6微塑料C=O含量减少,氢键作用力减弱是导致其对ST吸附能力减弱的主要原因。研究对认识微塑料的环境行为和环境风险提供了新的科学认识。

Effects of different aging condition on the adsorption of sulfathiazole by Polyamide 6 microplastic

Polyamide microplastics(PA-MPs)and sulfonamides(SAs)are emerging pollutants and widely detected.Polyamide 6 microplastic is produced by common Polyamide 6 plastic and sulfathiazole(ST)is a typical kind of SAs.Since microplastics are generally susceptible to aging in environmental exposure,the adsorption of ST by Polyamide 6 of unaged,ultraviolet aged and ultraviolet+H₂O₂ aged(recorded as PA6,PA6-UV and PA6-UV+H₂O₂) was explored.Results indicated that ST adsorption reached equilibrium within 24.0 h generally.The kinetics and the isotherms data could be well fitted by pseudo second-order model(R²≥0.969)and Freundlich model(R²≥0.967),respectively.The ability of Polyamide 6 microplastic to adsorb ST decreased due to aging,and the equilibrium adsorption capacity was PA6>PA6-UV>PA6-UV+H₂O₂.pH,salinity and DOM had different effect on the adsorption of ST by Polyamide 6 microplastic.The decrease of carbonyl group and hydrogen-bond interaction after aging were the main reasons for the decrease of adsorption capacity on ST by Polyamide 6 microplastic.The present study provided a new scientific cognition for understanding the environmental behavior and environmental risks of microplastics.