微塑料表面土霉素的吸附-解吸机制与动力学过程  

Mechanisms and kinetics of oxytetracycline adsorption-desorption onto microplastics

作　　者：张凯娜[1,2] 李嘉 李晓强[1] 张华 

机构地区：[1]烟台大学环境与材料工程学院,烟台264005 [2]中国科学院海岸带环境过程与生态修复重点实验室(烟台海岸带研究所),烟台264003 [3]中国科学院大学,北京100049

出　　处：《环境化学》2017年第12期2531-2540,共10页Environmental Chemistry

基　　金：国家重点研发计划重点专项(2016YFC1402202);中国科学院对外合作重点项目(KYSB20160003)资助~~

摘　　要：采用批量平衡实验的方法研究了土霉素(OTC)在聚乙烯(PE)和聚苯乙烯(PS)两种微塑料表面的吸附-解吸特性,通过扫描电镜(SEM)和傅里叶变换衰减全反射红外光谱(ATR-FTIR)探究了吸附机制.结果表明,OTC在两种微塑料表面的吸附量为:PS-纯水>PE-纯水>PS-海水>PE-海水,分别用线性模型、Freundlich模型和Langmuir模型对等温吸附实验数据进行拟合,结果显示Freundlich模型的拟合程度最高,OTC在两种微塑料上的吸附呈现明显的非线性(n=0.25—0.77),吸附位点存在异质性.吸附过程中没有出现新的基团,分子之间的范德华力以及表面微孔填充是OTC吸附的主要机制,微塑料表面存在的褶皱,裂隙等不规则结构提供了OTC吸附位点.微塑料表面OTC吸附动力学是多个过程共同作用的结果,其过程符合准二级动力学模型,吸附速率为0.0037—2.8 g·mg^(-1)·h^(-1),颗粒内扩散可能是主要的反应速率控制步骤.解吸实验结果显示,OTC的累积解吸量为:PS-纯水>PE-纯水>PS-海水>PE-海水,解吸过程符合准二级动力学模型.Batch equilibrium experiments were conducted to investigate adsorption and desorption characteristics of oxytetracycline（OTC） on polyethylene（PE） and polystyrene（PS） microplastics.Scanning electron microscop（SEM） and attenuated total reflectance-Fourier-transformed infrared spectroscopy（ATR-FTIR） were employed to study the interaction mechanisms between OTC and microplastic particles.The OTC adsorption capacities of the two microplastics were relatively weak and can be related to structural characteristics of the sorbent.Sorption amounts of OTC were as follows：PS-pure water PE-pure water PS-seawater PE-seawater.Sorption isotherms of OTC on the two microplastics can be well described by the Freundlich model,and showed obvious nonlinearcharacteristics（n = 0.25—0.77）.The pseudo-second order kinetic model successfully described adsorption kinetics of OTC with kinetic rates（k2） ranged from 0.0037 to 2.8 g·mg^（-1）·h^（-1）.Desorption experiments showed that the cumulative desorption of OTC as follows：PS-pure water PE-pure water PS-seawater PE-seawater.The result of SEM and ATR-FTIR showed that irregular features on PS-surface provided sorption sites for OTC.Van der Waals force and surface micropore filling are the two major mechanisms for the adsorption of OTC on the microplastics.

关 键 词：微塑料 土霉素(OTC) 吸附 解吸 

分 类 号：X132[环境科学与工程—环境科学]