Department of Environmental Engineering, Kyungpook National University , Buk-gu, Daegu 41566, South Korea.
Department of Civil, Structural and Environmental Engineering, University at Buffalo, The State University of New York , Buffalo, New York 14260, United States.
Environ Sci Technol. 2017 Nov 7;51(21):12405-12415. doi: 10.1021/acs.est.7b04037. Epub 2017 Oct 25.
Carbon-metal oxide nanohybrids (NHs) are increasingly recognized as the next-generation, promising group of nanomaterials for solving emerging environmental issues and challenges. This research, for the first time, systematically explored the transport and retention of carbon nanotube-magnetite (CNT-FeO) NH aggregates in water-saturated porous media under environmentally relevant conditions. A macromolecule modifier, carboxymethylcellulose (CMC), was employed to stabilize the NHs. Our results show that transport of the magnetic CNT-FeO NHs was lower than that of nonmagnetic CNT due to larger hydrodynamic sizes of NHs (induced by magnetic attraction) and size-dependent retention in porous media. Classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory can explain the mobility of NHs under varying experimental conditions. However, in contrast with colloid filtration theory, a novel transport feature-an initial lower and a following sharp-higher peaks occurred frequently in the NHs' breakthrough curves. The magnitude and location of both transport peaks varied with different experimental conditions, due to the interplay between variability of fluid viscosity and size-selective retention of the NHs. Promisingly, the estimated maximum transport distance of NHs ranged between ∼0.38 and 46 m, supporting the feasibility of employing the magnetically recyclable CNT-FeO NHs for in situ nanoremediation of contaminated soil, aquifer, and groundwater.
碳-金属氧化物纳米杂化材料（NHs）作为新一代有前途的纳米材料，越来越被认为能够解决新出现的环境问题和挑战。本研究首次系统地研究了在环境相关条件下，碳纳米管-磁铁矿（CNT-FeO）NH 聚集体在水饱和多孔介质中的迁移和滞留。采用高分子改性剂羧甲基纤维素（CMC）稳定 NHs。研究结果表明，由于 NHs 的水动力尺寸较大（由磁性吸引引起）以及在多孔介质中的尺寸依赖性滞留，磁性 CNT-FeO NHs 的迁移率低于非磁性 CNT。经典的德加古因-朗道-维尔韦尔-奥弗贝克（DLVO）理论可以解释 NHs 在不同实验条件下的迁移行为。然而，与胶体过滤理论不同的是，在 NHs 的穿透曲线中经常出现初始较低且随后急剧升高的新型传输特征。由于流体粘度的变化和 NHs 的尺寸选择性滞留之间的相互作用，两个传输峰的幅度和位置随不同的实验条件而变化。有希望的是，NHs 的估计最大迁移距离在 0.38 到 46 m 之间，这支持了使用可磁回收的 CNT-FeO NHs 原位修复污染土壤、含水层和地下水的可行性。
