Interfacial Forces are Modified by the Growth of Surface Nanostructures

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Interfacial Forces are Modified by the Growth of Surface Nanostructures

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Title: Interfacial Forces are Modified by the Growth of Surface Nanostructures
Author: Martin, Scot; Na, Chongzheng

Note: Order does not necessarily reflect citation order of authors.

Citation: Na, Chongzheng and Scot T. Martin. 2008. Interfacial forces are modified by the growth of surface nanostructures. Environmental Science and Technology 42, no. 18: 6883–6889.
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Abstract: Nanostructures formed by chemical reaction can modify the interfacial forces present in aqueous solution near a surface. This study uses force-volume microscopy to explore this phenomenon for the growth of manganese oxide nanostructures on rhodochrosite. The interfacial forces above the oxide nanostructures are dominated by electrostatic repulsion for probe−surface separations greater than ca. 2 nm but are overtaken by van der Waals attraction for shorter distances. Across the investigated pH range 5.0−9.7, the maximum repulsive force occurs 2.4 (±1.1) nm above the oxide nanostructures. The magnitude of the repulsive force decreases from pH 5.0 to 6.5, reaches its minimum at 6.5, and then increases steadily up to pH 9.7. Specifically, fmax(pN) = 23(±4)[6.8(±2.1) pH] for pH < 6.5 and fmax(pN) = 19(±2)[pH 6.1(±1.0)] for pH ≥ 6.5. This dependence indicates that oxide nanostructures have a point of zero charge in the pH range 6−7. In comparison to the nanostructures, the rhodochrosite substrate induces only small interfacial forces in the same pH range, suggesting a neutral or weakly charged surface. The quantitative mapping of interfacial forces, along with the associated influencing factors such as pH or growth of nanostructures, provides a basis for more sophisticated and accurate modeling of processes affecting contaminant immobilization and bacterial attachment on mineral surfaces under natural conditions.
Published Version: http://dx.doi.org/10.1021/es800839a
Other Sources: http://www.seas.harvard.edu/environmental-chemistry/publications/Na_EST_2008.pdf
Citable link to this page: http://nrs.harvard.edu/urn-3:HUL.InstRepos:2958608

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  • FAS Scholarly Articles [7262]
    Peer reviewed scholarly articles from the Faculty of Arts and Sciences of Harvard University
 
 

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