School of Environment and Resources, Zhejiang Agriculture and Forestry University, Hangzhou, 311300, China.
School of Environment and Resources, Zhejiang Agriculture and Forestry University, Hangzhou, 311300, China.
Environ Pollut. 2018 Dec;243(Pt B):1550-1557. doi: 10.1016/j.envpol.2018.09.122. Epub 2018 Sep 28.
Microplastic polystyrene foam has been found widely in the environment and is readily transported by wind or water. Beached and virgin foams of size 0.45-1 mm were prepared as sorbents to study oxytetracycline sorption. Enhanced adsorption were found in the beached foams compared to the virgin foams, corresponding to the higher specific surface area, micropore area and the degree of oxidation of the former. The Freundlich K value was 894 ± 84 ((mg kg) (mg L)) for oxytetracycline adsorption on the beached foams, approximately twice as high as on the virgin foams. Effects of solution pH on adsorption to the beached foams were more pronounced to the virgin foams. Maximum adsorption occurred at pH 5 at which electrostatic repulsion between the microplastic surface and the oxytetracycline zwitterion was minimal, indicating that electrostatic interaction may have regulated adsorption. Moreover, H-bonding and multivalent cationic bridging mechanisms may also have affected the adsorption of oxytetracycline to the beached foams as reflected by the ionic effects. Adsorption was promoted more in the presence of humic acid than of fulvic acid, perhaps owing to π-π conjugation between the humic acid and the microplastic surface which led to enhanced electrostatic attraction for oxytetracycline. This study suggests that weathered polystyrene foams may act as carriers of antibiotics in the environment and their potential risks to ecosystem and human health merit further investigation.
微塑料聚苯乙烯泡沫已广泛存在于环境中，很容易被风和水携带。将海滩和原始尺寸为 0.45-1 毫米的泡沫作为吸附剂来研究土霉素的吸附。与原始泡沫相比，海滩泡沫的吸附增强，这与前者具有更高的比表面积、微孔面积和氧化程度相对应。海滩泡沫上吸附土霉素的 Freundlich K 值为 894±84(mg kg)·(mg L)，约为原始泡沫的两倍。溶液 pH 值对海滩泡沫吸附的影响比对原始泡沫更为明显。最大吸附发生在 pH 5 时，此时微塑料表面和土霉素两性离子之间的静电斥力最小，表明静电相互作用可能调节了吸附。此外，氢键和多价阳离子桥接机制也可能影响土霉素在海滩泡沫上的吸附，这反映在离子效应上。在腐殖酸存在的情况下，吸附比富里酸更促进，这可能是由于腐殖酸与微塑料表面之间的π-π共轭作用导致对土霉素的静电吸引力增强。本研究表明，风化聚苯乙烯泡沫可能在环境中充当抗生素的载体，它们对生态系统和人类健康的潜在风险值得进一步研究。
