Citation:

Wang, D., C. Park, A. Masud, N. Aich, AND C. Su. Carboxymethylcellulose Mediates the Transport of Carbon Nanotube-Magnetite Nanohybrid Aggregates in Water-Saturated Porous Media. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 51(21):12405-12415, (2017). https://doi.org/10.1021/acs.est.7b04037

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Submitting to Environmental Science & Technology.

Description:

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 nanotubes-magnetite (CNT-Fe3O4) NHs in water-saturated porous media under environmentally relevant conditions. An environment-benign macromolecule, carboxymethylcellulose (CMC), was employed to stabilize the NHs. Our results show that transport of the magnetic CNT-Fe3O4 NHs was lower than that of non-magnetic CNT due to larger hydrodynamic sizes of NHs (induced by magnetic attraction) and size-dependent retention in porous media. The Derjaguin-Landau-Verwey-Overbeek (DLVO) theory can explain the mobility of NHs with varying experimental conditions. However, in contrast with colloid filtration theory, a novel transport feature─an initial lower and following sharp, higher peaks occurred frequently in the NHs’ breakthrough curves and 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 0.38−46 m, supporting the feasibility of employing the magnetically recyclable CNT-Fe3O4 NHs for in-situ nanoremediation of contaminated soils, aquifers, and groundwater.

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