Civil & Environmental Engineering Department (CEE), Amirkabir University of Technology (Tehran Polytechnic), Hafez Ave., 424, 15875-4413 Tehran, Iran.
Civil & Environmental Engineering Department (CEE), Amirkabir University of Technology (Tehran Polytechnic), Hafez Ave., 424, 15875-4413 Tehran, Iran.
Sci Total Environ. 2020 Jan 1;698:134224. doi: 10.1016/j.scitotenv.2019.134224. Epub 2019 Sep 2.
This study focuses on the transport in porous media of graphene oxide nanoparticles (GONP) under conditions similar to those applied in the generation of in-situ reactive zones for groundwater remediation (i.e. GO concentration of few tens of mg/l, stable suspension in alkaline solution). The experimental tests evaluated the influence on GO transport of three key factors, namely particle size (300-1200 nm), concentration (10-50 mg/L), and sand size (coarse to fine). Three sources of GONP were considered (two commercial and one synthesized in the laboratory). Particles were stably dispersed in water at pH 8.5 and showed a good mobility in the porous medium under all experimental conditions: after injection of 5 pore volumes and flushing, the highest recovery was around 90%, the lowest around 30% (only for largest particles in fine sand). The particle size was by far the most impacting parameter, with increasing mobility with decreasing size, even if sand size and particle concentration were also relevant. The source of GONP showed a minor impact on the mobility. The transport test data were successfully modeled using the advection-dispersion-deposition equations typically applied for spherical colloids. Experimental and modeling results suggested that GONP, under the explored conditions, are retained due to both blocking and straining, the latter being relevant only for large particles and/or fine sand. The findings of this study play a key role in the development of an in-situ groundwater remediation technology based on the injection of GONP for contaminant degradation or sorption. Despite their peculiar shape, GONP behavior in porous media is comparable with spherical colloids, which have been more studied by far. In particular, the possibility of modeling GONP transport using existing models ensures that they can be applied also for the design of field-scale injections of GONP, similarly to other particles already used in nanoremediation.
本研究重点关注氧化石墨烯纳米颗粒（GONP）在类似于原位反应区生成条件下在多孔介质中的传输，这些条件适用于地下水修复（即 GO 浓度为几十毫克/升，在碱性溶液中稳定悬浮）。实验测试评估了三个关键因素对 GO 传输的影响，即粒径（300-1200nm）、浓度（10-50mg/L）和砂粒径（粗砂至细砂）。研究考虑了三种 GONP 来源（两种商业来源和一种实验室合成来源）。颗粒在 pH 8.5 的水中稳定分散，并在所有实验条件下在多孔介质中表现出良好的迁移性：注入 5 个孔隙体积并冲洗后，最高回收率约为 90%，最低回收率约为 30%（仅对细砂中的最大颗粒而言）。粒径是迄今为止最具影响力的参数，粒径越小，迁移性越高，即使砂粒径和颗粒浓度也很重要。GONP 的来源对迁移性的影响较小。使用通常适用于球形胶体的对流-弥散-沉积方程成功地对传输测试数据进行了建模。实验和建模结果表明，在探索的条件下，GONP 由于堵塞和滞留而被保留，后者仅对大颗粒和/或细砂相关。本研究的结果在开发基于注入 GONP 降解或吸附污染物的原位地下水修复技术方面发挥了关键作用。尽管 GONP 具有特殊的形状，但它们在多孔介质中的行为与迄今为止研究得更多的球形胶体相似。特别是，使用现有模型模拟 GONP 传输的可能性确保了它们也可以用于设计 GONP 的现场规模注入，类似于已经用于纳米修复的其他颗粒。
