| 典型雌激素在微塑料上的吸附特征及位点能量分布 |
| 摘要点击 1539 全文点击 411 投稿时间：2022-05-06 修订日期：2022-07-11 |
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| 中文关键词 聚乙烯(PE) 雌激素 吸附 位点能量 微塑料(MPs) |
| 英文关键词 polyethylene(PE) estrogens adsorption energy distribution microplastics (MPs) |
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| 中文摘要 |
| 微塑料（MPs）和雌激素是目前备受关注的新型污染物，MPs可作为环境中雌激素的载体而产生复合污染.为了解聚乙烯（PE）为代表的MPs对典型雌激素的吸附特性，采用批平衡吸附实验法，借助X射线光电子能谱（XPS）和傅里叶红外光谱（FTIR）等研究不同体系下PE对6种典型雌激素的吸附行为和位点能量分布情况.结果表明，在不同初始浓度（100 μg ·L-1和1000 μg ·L-1），PE对目标雌激素的吸附过程更符合准二级动力学模型，初始浓度的增加会影响吸附平衡时间和雌激素吸附量占比.在单一体系（单一雌激素）和复合体系（6种雌激素共存）中，雌激素在PE上的吸附更符合Freundlich模型（R2>0.94）.等温吸附实验结果及XPS和FTIR表征结果表明，吸附过程主要受范德华力和疏水分配作用影响；单一己烯雌酚（DES）体系中出现的C—O—C官能团和单一炔雌醇（17α-EE2）体系中出现的C—O—C及O—C O官能团，表明化学键合作用对合成雌激素在MPs上的吸附有一定的影响，而对天然雌激素基本没有影响.与单一体系相比，复合体系中各雌激素的吸附位点能量整体向高位能区偏移，位点能量增加了2.15%~40.98%，其中，己烯雌酚（DES）的位点能量变化最为显著，说明其在复合体系中具有竞争优势.以上研究结果可以为有机污染物和微塑料共存情况下的吸附行为、作用机制和环境风险研究提供参考. |
| 英文摘要 |
| Microplastics (MPs) and estrogens are high-profile emerging contaminants at present, and MPs might become the carrier of estrogens in the environment and induce combined pollution. To study the adsorption behavior of polyethylene (PE) microplastics to typical estrogens, the adsorption isothermal properties of the six estrogens[estrone (E1), 17α-estradiol (17α-E2), 17β-estradiol (17β-E2), estriol (E3), diethylstilbestrol (DES), and ethinylestradiol (17α-EE2)] in single-solute and mixed-solute systems were studied through batch equilibrium adsorption experiments, in which the PE microplastics before and after adsorption were characterized by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). Then, the site energy distribution theory of the adsorption of six estrogens on PE microplastics was further analyzed based on the Freundlich model. The results showed that the adsorption process of selected estrogens with two concentrations (100 μg·L-1 and 1000 μg·L-1) on PE were more consistent with the pseudo-second order kinetic model. The increase in initial concentration reduced the equilibrium time of adsorption and increased the adsorbing capacity of estrogens on PE. In the single system (one estrogen) or mixed system (six estrogens) with different concentrations (10 μg·L-1-2000 μg·L-1), the Freundlich model showed the best fitting effect for the adsorption isotherm data (R2>0.94). The results of isothermal adsorption experiments and XPS and FTIR spectra showed that the adsorption of estrogens on PE in the two systems was heterogeneous adsorption, and hydrophobic distribution and van der Waals forces were the principal factors in the process of adsorption. The occurrence of C-O-C (in only the DES and 17α-EE2 systems) and O-C[FY=,1]O (in only the 17α-EE2 system) indicated that the adsorption of synthetic estrogens on PE was affected slightly by chemical bonding function, but no obvious effects were observed for natural estrogens. The results of site energy distribution analysis showed that, compared with the single system, the adsorption site energy of each estrogen shifted to the high-energy region in its entirety in the mixed system, and the site energy increased by 2.15%-40.98%. The energy change in DES was the most significant among all of the estrogens, indicating its competitive advantage in the mixed system. The above results of this study can provide some reference for the study of adsorption behavior, mechanism of action, and environmental risks under the coexisting condition of organic pollutants and MPs. |
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