Since iron oxide minerals are ubiquitous in natural environments, the release of graphene oxide (GO) into environmental ecosystems can potentially interact with iron oxide particles and thus alter their surface properties, resulting in the change of their transport behaviors in subsurface systems. Column experiments were performed in this study to investigate the co-transport of GO nanoparticles and hematite colloids (a model representative of iron oxides) in saturated sand. The results demonstrated that the presence of hematite inhibited GO transport in quartz sand columns due to the formation of less negatively charged GO-hematite heteroaggregates and additional deposition sites provided by the adsorbed hematite on sand surfaces. Contrarily, GO co-present in suspensions significantly enhanced the transport of hematite colloids through different mechanisms such as the increase of electrostatic repulsion, decreased physical straining, GO-facilitated transport of hematite (i.e., highly mobile GO nanoparticles served as a mobile carrier for hematite). We also found that the co-transport behaviors of GO and hematite depended on solution chemistry (e.g., pH, ionic strength, and divalent cation (i.e., Ca²⁺)), which affected the electrostatic interaction as well as heteroaggregation behaviors between GO nanoparticles and hematite colloids. The findings provide an insight into the potential fate of carbon nanomaterials affected by mineral colloids existing in natural waters and soils.

由于氧化铁矿物在自然环境中无处不在，因此氧化石墨烯（GO）向环境生态系统的释放可能会与氧化铁颗粒发生相互作用，从而改变其表面性质，从而导致其在地下系统中的运输行为发生变化。在这项研究中进行了柱实验，以研究GO纳米颗粒和赤铁矿胶体（代表氧化铁的模型）在饱和砂土中的共同运输。结果表明，赤铁矿的存在抑制了石英砂柱中GO的运移，这是由于形成的带负电荷的GO-赤铁矿异质聚集体的形成以及砂岩表面吸附的赤铁矿提供了额外的沉积位置。相反，悬浮液中共存的GO通过不同的机制显着增强了赤铁矿胶体的运输，例如增加了静电排斥力，降低了物理应变，GO促进了赤铁矿的运输（即，高度移动的GO纳米颗粒充当了赤铁矿的移动载体）。我们还发现GO和赤铁矿的共运行为取决于溶液化学性质（例如pH值，离子强度和二价阳离子（即Ca²⁺）），这影响了GO纳米粒子与赤铁矿胶体之间的静电相互作用以及杂聚行为。这些发现为洞悉天然水和土壤中存在的矿物胶体影响碳纳米材料的潜在命运。