Abstract：
This research explored the effects of widely utilized nanomaterial graphene oxide (GO) and organic matter humic acid (HA) on the transport of microplastics under different ionic solution strengths in bare sand and iron oxide-coated sand. The results found transport of polystyrene microplastics (PS) did not respond to the presence of HA in sand that contains large amounts of iron oxide. Compared to bare quartz sand, ionic strength had little effect: <20 % of PS passed through Fe sand columns. There was a significant promotion of PS transport in the presence of GO, however, which can be attributed to the increased surface electronegativity of PS and steric hindrance. Moreover, GO combined with HA significantly promoted the transport of PS in the Fe sand, and transport further increased when the concentration of HA increased from 5 to 10 mg/L. Interestingly, the degree of this increase exactly corresponded to the change in the surface charge of the microplastics, demonstrating that electrostatic interaction dominated the PS transport. Further results indicated that co-existing pollutants had significant impacts on the transport of microplastics under various conditions by altering the surface characteristics of the plastic particles and the spatial steric hindrance within porous media. This research will offer insights into predicting the transport and fate of microplastics in complex environments.
摘要：
这项研究探索了广泛使用的纳米材料氧化石墨烯（GO）和有机物腐殖酸（HA）在裸砂和氧化铁涂层砂中不同离子溶液强度下对微塑料传输的影响。结果发现，聚苯乙烯微塑料（PS）的运输对含有大量氧化铁的沙子中HA的存在没有反应。与裸露的石英砂相比，离子强度几乎没有影响:<20%的PS通过Fe砂柱。在GO的存在下，PS的运输有显著的促进作用，然而,这可以归因于PS的表面电负性增加和空间位阻。此外，GO与HA结合显著促进了PS在Fe砂中的运移，当HA的浓度从5mg/L增加到10mg/L时，转运进一步增加。有趣的是,这种增加的程度正好与微塑料表面电荷的变化相对应，证明静电相互作用主导了PS传输。进一步的结果表明，共存污染物通过改变塑料颗粒的表面特性和多孔介质中的空间空间位阻，在各种条件下对微塑料的传输产生重大影响。这项研究将为预测微塑料在复杂环境中的运输和命运提供见解。
