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Rapid industrial scale production, coupled with unique material properties, underpin rising concerns of engineered nano-scale materials such as carbon based, nano-scale materials like fullerenes and nanotubes inadvertently impacting the health and function of natural systems. Fundamentally understanding the behaviour of these materials in natural matrixes particularly the interactions with high-surface area, charged sub-surface fractions such as clay minerals, metal oxyhydroxides, and natural organic matter is an important issue. Research presented herein details specific interactions between C60 as an aggregate suspension (20 – 150 nm crystalline aggregates of underivatized fullerenes in water - termed nano-C60 [Fortner et al. ES&T 2005]) and clay minerals; specifically, with smectite (Calcigel; Sudchemie AG and Cloisite 10A; Southern Clay Inc. Texas), kaolinite (KGa-1; CMS source clay), and synthetic layered double hydroxide (LDH Syntal HSA 696; Sudchemie AG). Batch and 1-D bench-scale, flow through column systems operated at saturation with variable sand/clay mixtures were analyzed with TEM, XRD and UV/VIS spectroscopy. Results indicate that nano-C60, suspended in water, does specifically interact with clay mineral surfaces. These interactions are primarily dominated by positively charged points on mineral surface in relation to the net negative surface charge of nano-C60 (as an electrostatic interaction). Specifically, LDH, a positively charged material, sorbed 5 - 25% more than all other clay types tested based on higher surface charge (positive) density. 1-D column tests indicate that LDH retards nano-C60 transport significantly compared to other clay materials tested. Taken together, research presented provides new and critical information about the governing factors controlling transport of nano-C60 through porous media with charged clay fractions. Such information is important not only for environmental fate and transport modelling but also for appropriate design and maintenance of solid waste disposal facilities engineered to contain these and other charged nano-scale materials.
Authors:Plötze, Michael and Puzrin, Alexander and Hughes, Joseph and Fortner, John
Index Terms:ClayGroup; c60; fullerene; kaolinite; ldh; montmorillonite; Fortner, John; Hughes, Joseph; Plotze, Michael; Puzrin, Alexander
Further Information:Date published: 2009