College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, China; Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, Yangling, 712100, China.
College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, China.
Chemosphere. 2019 Mar;218:1-13. doi: 10.1016/j.chemosphere.2018.11.089. Epub 2018 Nov 15.
The ability to predict the transport of heavy metal ions in porous media with different surface characteristics is crucial to protect groundwater quality and public health. In this study, the effects of graphene oxide (GO) on co-transport and remobilization of Pb and Cd in humic acid (HA), smectite, kaolinite, and ferrihydrite-coated sand media were evaluated via laboratory packed-column experiments. Scanning electron microscope and energy dispersive X-ray analysis showed that the surface morphology of the coated sands was quite different and that ∼56.7-89.9% of the surface was covered by the coating and the major elemental components were C, O, Si, Al, and Fe. GO exhibited high mobility in HA, kaolinite, and smectite-coated sand, but showed high retention in ferrihydrite-coated sand. While GO reduced the transport of Pb and Cd, both metal ions also reduced the mobility of GO in coated-sand columns. Elution experiments revealed that GO led to the remobilization and release of the previously sorbed Pb and Cd from the coated sand. However, GO could not release Pb and Cd from smectite-coated sand columns, probably because smectite has stronger adsorption affinity to the heavy metals than GO. Derjaguin-Landau-Verwey-Overbeek calculations were employed and explained the GO transport behavior in the columns well. Furthermore, the advection-dispersion-reaction equation simulated the cotransport of Pb and Cd with GO in the coated sand well. These results are expected to provide insight into the potential impact of coexisting nanomaterials with contaminants in vulnerable soil and groundwater systems.
预测具有不同表面特征的多孔介质中重金属离子迁移的能力对于保护地下水质量和公众健康至关重要。在这项研究中，通过实验室填充柱实验评估了氧化石墨烯（GO）对腐殖酸（HA）、蒙脱石、高岭石和水铁矿涂层砂介质中 Pb 和 Cd 共迁移和再迁移的影响。扫描电子显微镜和能谱分析表明，涂层砂的表面形貌有很大的不同，约 56.7-89.9%的表面被涂层覆盖，主要的元素成分是 C、O、Si、Al 和 Fe。GO 在 HA、高岭石和蒙脱石涂层砂中表现出高迁移性，但在水铁矿涂层砂中表现出高保留性。虽然 GO 减少了 Pb 和 Cd 的迁移，但这两种金属离子也降低了 GO 在涂层砂柱中的迁移性。洗脱实验表明，GO 导致先前吸附在涂层砂上的 Pb 和 Cd 的再移动和释放。然而，GO 不能从蒙脱石涂层砂柱中释放 Pb 和 Cd，可能是因为蒙脱石对重金属的吸附亲和力比 GO 更强。德加古因-朗道-弗伦德里希-奥弗贝克计算被用来很好地解释了 GO 在柱中的输运行为。此外，对流-弥散-反应方程很好地模拟了 Pb 和 Cd 与 GO 在涂层砂中的共输运。这些结果有望为了解共存纳米材料与脆弱土壤和地下水系统中污染物的潜在影响提供深入了解。
