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Adsorption of tetracyclines onto polyethylene microplastics: A combined study of experiment and molecular dynamics simulation
Chemosphere ( IF 8.8 ) Pub Date : 2020-11-28 , DOI: 10.1016/j.chemosphere.2020.129133
Yajun Chen , Jining Li , Fenghe Wang , Hao Yang , Lei Liu

Microplastics are a kind of new organic pollutant in the environment. In this study, the adsorption of tetracyclines (TCs), including tetracycline hydrochloride (TC), chlortetracycline hydrochloride (CTC) and oxytetracycline hydrochloride (OTC) onto polyethylene (PE) microplastics in aqueous solutions were investigated. The mechanism of the adsorption behavior was preliminarily explored by adsorption kinetics, isotherms, and thermodynamics, in combination with scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). In addition, molecular dynamics (MD) simulation was applied to investigate the adsorption processes of TCs on PE at a molecular level. It was found that the adsorption behaviors of TCs reached an equilibrium state within 30 h. The experimental data showed that adsorption capacities of TCs onto PE were as follows: OTC (64.40±2.38 μg/g)>CTC (63.36±4.92 μg/g)>TC (53.52±3.43 μg/g). TC sorption onto PE increased with pH, peaking at around pH 6 and then decreased. The increase of ionic strength in the solution led to the reduced adsorption capacity of TC onto PE. The results indicated that the experimental data were well fitted by the pseudo-second-order model and the Freundlich isotherm model, indicating both monolayer and multilayer coverage of TCs onto the surface of PE. The results of MD simulation showed that PE can effectively adsorb the TCs molecule mainly through non-bond interactions, and PE exhibited the highest affinity for CTC and OTC, followed by TC.



中文翻译:

四环素在聚乙烯微塑料上的吸附:实验与分子动力学模拟的组合研究

微塑料是环境中的一种新型有机污染物。在这项研究中,研究了四环素(TCs)在水溶液中对聚乙烯(PE)微塑料的吸附,其中包括四环素盐酸盐(TC),盐酸四环素(CTC)和盐酸土霉素(OTC)。通过吸附动力学,等温线和热力学,结合扫描电子显微镜(SEM),傅里叶变换红外光谱(FTIR)和X射线光电子能谱(XPS),初步探讨了吸附行为的机理。此外,分子动力学(MD)模拟被用来研究TCs在分子水平上在PE上的吸附过程。发现TCs的吸附行为在30 h内达到平衡状态。实验数据表明,TCs在PE上的吸附能力为:OTC(64.40±2.38μg/ g)> CTC(63.36±4.92μg/ g)> TC(53.52±3.43μg/ g)。TC在PE上的吸附随pH的增加而增加,在pH约为6时达到峰值,然后下降。溶液中离子强度的增加导致TC在PE上的吸附能力降低。结果表明,实验数据与拟二阶模型和Freundlich等温线模型拟合良好,表明TCs在PE表面的单层和多层覆盖。MD模拟结果表明,PE主要通过非键相互作用有效吸附TCs分子,PE对CTC和OTC的亲和力最高,其次为TC。43微克/克)。TC在PE上的吸附随pH的增加而增加,在pH约为6时达到峰值,然后下降。溶液中离子强度的增加导致TC在PE上的吸附能力降低。结果表明,实验数据与拟二阶模型和Freundlich等温线模型拟合良好,表明TCs在PE表面的单层和多层覆盖。MD模拟结果表明,PE主要通过非键相互作用有效吸附TCs分子,PE对CTC和OTC的亲和力最高,其次为TC。43微克/克)。TC在PE上的吸附随pH的增加而增加,在pH约为6时达到峰值,然后下降。溶液中离子强度的增加导致TC在PE上的吸附能力降低。结果表明,实验数据与拟二阶模型和Freundlich等温线模型拟合良好,表明TCs在PE表面的单层和多层覆盖。MD模拟结果表明,PE主要通过非键相互作用有效吸附TCs分子,PE对CTC和OTC的亲和力最高,其次为TC。结果表明,实验数据与拟二阶模型和Freundlich等温线模型拟合良好,表明TCs在PE表面的单层和多层覆盖。MD模拟结果表明,PE主要通过非键相互作用有效吸附TCs分子,PE对CTC和OTC的亲和力最高,其次为TC。结果表明,实验数据与拟二阶模型和Freundlich等温线模型拟合良好,表明TCs在PE表面的单层和多层覆盖。MD模拟结果表明,PE主要通过非键相互作用有效吸附TCs分子,PE对CTC和OTC的亲和力最高,其次为TC。

更新日期:2020-12-01
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