Benzo[a]pyrene and heavy metal ion adsorption on nanoplastics regulated by humic acid: Cooperation/competition mechanisms revealed by molecular dynamics simulations
Benzo[a]pyrene and heavy metal ion adsorption on nanoplastics regulated by humic acid: Cooperation/competition mechanisms revealed by molecular dynamics simulations
复制标题
腐殖酸调控纳米塑料上苯并[a]芘和重金属离子的吸附：分子动力学模拟揭示的合作/竞争机制
DOI：
10.1016/j.jhazmat.2021.127431
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发表时间：
2021-10-13
影响因子：
13.6
通讯作者：
Yue, Tongtao
中科院分区：
文献类型：
--
作者：
Feng, Hao;Liu, Yingjie;Yue, Tongtao
纳米塑料吸附污染物和有机物，加重或减轻对生态环境和人类健康的影响。然而，相互作用的机制仍然不清楚，很难用现有的实验技术来研究。通过分子动力学模拟，研究了不同材料的纳米塑料对苯并[a]芘(BaP)和重金属离子(Cu2+)的吸附以及腐植酸(HA)对表面电荷的调节。在所考虑的材料中，聚苯乙烯通过与苯环形成夹心pi堆积结构而显示出最高的吸附BAPS的能力。在疏水、静电和氢键作用的驱动下，BAPS和Cu2+分别自发聚集成具有疏水核心和带电外部的胶束状结构。阳离子和中性纳米塑料吸附更多的必须形成生态冠冕，通过以下合作/竞争机制调节BaP和Cu2+的吸附。一方面，BAPS与纳米塑料的直接结合被HAS通过BaP包埋和竞争吸附所阻碍。另一方面，吸附后暴露了羧基，提供了丰富的结合部位，促进了中性和阳离子纳米塑料对Cu2+的吸附，而未结合的纳米塑料与阴离子纳米塑料竞争抑制了Cu2+的吸附。这些结果为纳米塑料在水环境中与共存污染物的传输、转化和可获得性提供了分子水平的见解。
Nanoplastics adsorb pollutants and organic matter to aggravate or alleviate impact to the eco-environment and human health. However, the interaction mechanisms remain unclear and difficult to study using current experimental techniques. By means of molecular dynamics simulation, here we investigate adsorption of benzo[a]pyrene (BaP) and heavy metal ions (Cu2+) on nanoplastics of different materials and surface charges regulated by humic acid (HA). Among considered materials, polystyrene shows the highest capacity of adsorbing BaPs via forming sandwiched pi-stacking structures with benzene rings. Driven by hydrophobic, electrostatic and hydrogen bonding interactions, HAs spontaneously aggregate into micelle-like structures with hydrophobic core and charged exterior accessible to BaPs and Cu2+, respectively. Cationic and neutral nanoplastics adsorb more HAs to form eco-coronas, which modulate BaP and Cu2+ adsorption via following cooperation/competition mechanisms. On one hand, the direct binding of BaPs to nanoplastics is hindered by HAs through BaP encapsulation plus competitive adsorption. On the other hand, adsorbed HAs expose carboxyl groups to offer rich binding sites to promote Cu2+ adsorption on neutral and cationic nanoplastics, while unbound HAs compete with anionic nanoplastics to inhibit Cu2+ adsorption. These results provide molecular level insights into transport, transformation and accessibility of nanoplastics with coexisting contaminants in the aqueous environment.