在缺氧环境中，经紫外老化后的微塑料对诺氟沙星的吸附作用降低。
Reduced adsorption of norfloxacin on UV aging microplastics in anoxic environment.
机构信息
School of Environment and Resource, Southwest University of Science and Technology, Mianyang, 621010, China.
Tianfu Institute of Research and Innovation, Southwest University of Science and Technology, Chengdu, 610299, China.
出版信息
Environ Sci Pollut Res Int. 2023 May;30(25):67174-67186. doi: 10.1007/s11356-023-26771-2. Epub 2023 Apr 27.
Over recent years, much attention has been paid to aging problem of microplastics and adsorption behavior of antibiotic on microplastics. In this study, four microplastics, including polystyrene (PS), polypropylene (PP), polyamide (PA) and polyethylene (PE), were photoaged by UV light in anoxic environment. The surface characteristics of microplastics and adsorption behavior of norfloxacin (NOR) on microplastics were investigated. Results indicated that the specific surface area and crystallinity increased, and hydrophobicity weakened of microplastics after UV aging. The content of C element decreased and the content of O barely changed in the aged microplastics. In addition, the adsorption of NOR on microplastics yielded a better fitness for the pseudo-second-order kinetics, Langmuir and Freundlich models. The adsorption capacities of NOR on PS, PA, PP, and PE at 288 K were 16.01, 15.12, 14.03, and 13.26 mg·g, respectively, while the adsorption capacities of NOR on aged microplastics were reduced to 14.20, 14.19, 11.50, and 10.36 mg·g, respectively, due to decrease of hydrophobicity and increase of crystallinity of microplastics after UV aging. The adsorption of NOR on microplastics decreased with the increase of temperature, implying the adsorption process was exothermic. Adsorption mechanism analysis showed that Van der Waals force was the main influential mechanism of the adsorption of NOR on PP and PE, and hydrogen bond was the main factor affecting the adsorption of NOR on PA, while the π-π interaction was the main mechanism impacting the adsorption of NOR on PS. Aging time and salinity significantly affect the adsorption of NOR on microplastics. With the increase of humic acid concentration and pH, the adsorption of NOR on microplastics first reduced and then rose. This study provides a basis for further clarifying the mechanism of UV aging microplastics and a reference for the study of combined pollution behavior of microplastics and antibiotics.
近年来，人们对微塑料的老化问题和抗生素在微塑料上的吸附行为给予了极大关注。本研究采用紫外光在缺氧环境下对聚苯乙烯（PS）、聚丙烯（PP）、聚酰胺（PA）和聚乙烯（PE）四种微塑料进行光老化，探讨了微塑料的表面特性和诺氟沙星（NOR）在微塑料上的吸附行为。结果表明，紫外光老化后微塑料的比表面积和结晶度增加，疏水性减弱。老化微塑料中 C 元素的含量减少，而 O 元素的含量几乎不变。此外，NOR 在微塑料上的吸附更符合准二级动力学、Langmuir 和 Freundlich 模型。288 K 时，NOR 在 PS、PA、PP 和 PE 上的吸附容量分别为 16.01、15.12、14.03 和 13.26 mg·g-1，而紫外光老化后微塑料的吸附容量分别降低至 14.20、14.19、11.50 和 10.36 mg·g-1，这是由于微塑料光老化后疏水性降低和结晶度增加所致。NOR 在微塑料上的吸附随温度升高而降低，表明吸附过程为放热过程。吸附机制分析表明，范德华力是 NOR 在 PP 和 PE 上吸附的主要影响机制，氢键是影响 NOR 在 PA 上吸附的主要因素，而π-π 相互作用是影响 NOR 在 PS 上吸附的主要机制。老化时间和盐度对 NOR 在微塑料上的吸附有显著影响。随着腐殖酸浓度和 pH 的增加，NOR 在微塑料上的吸附先降低后升高。本研究为进一步阐明微塑料紫外光老化机制提供了依据，为研究微塑料与抗生素的复合污染行为提供了参考。
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