Es

Where er is the relative dielectric constant of the liquid, e0 is the permittivity of the vacuum, is electrokinetic or zeta potential of diffuse layer of charged particles, and k is the reciprocal Debye length. Applying classical DLVO theory, an energy barrier of RNIP is predicted to be 7.0 kBT (Figure 8.10). This energy barrier is sufficient to prevent rapid aggregation, suggesting that dispersions of these particles should be stable. This contrasts the observed behavior. Iron nanoparticles...

Nanotechnology and the Environment

Wiesner Duke University, Durham, NC Jean-Yves Bottero CNRS-University of Aix-Marseille, Aix-en-Provence, France Advances in information technologies, materials science, biotechnology, energy engineering, and many other disciplines including environmental engineering are converging at the quantum and molecular scales. This molecular terrain is common ground for interdisciplinary research and education that will be an essential component of science and engineering in the future. Much like...

Ho2cr

Initial syntheses were carried out using the acid as the solvent or xylene 80, 81 , however, subsequent research demonstrated the use of water as a solvent and acetic acid as the most convenient capping agent 82 . A solventless synthesis has also been developed 83 . Thus, the synthesis Figure 3.16 Structural relationship of the capping ligand for (a) siloxy and (b) carboxylate alu-moxane nanoparticles. Figure 3.16 Structural relationship of the capping ligand for (a) siloxy and (b) carboxylate...

Acknowledgements

The work described in this chapter was supported by the US Public Health Service Grants, U19 A1070453 (funded by National Institute of Allergy and Infectious Diseases and National Institute of Environmental and Health Science), RO1 ES10553 (National Institute of Environmental and Health Science) R01 ES 015498 and RO1 ES10253, as well as the US Environmental Protection Agency STAR award to the Southern California Particle Center RD-83241301. This work has not been subjected to the Environmental...

Metal Sulfide Surface Chemistry and Free Radical Generation

Metal sulfide and related chalocogenide semiconductors are used in a variety of electronic applications. For example, CdS, which is an n-type semiconductor with Eg 2.4 eV, has been shown to have photocatalytic activity for H2 production under visible light irradiation under anoxic conditions in water in the presence of electron donors such as C2H5OH, HS and SO2 . The electronic levels of nanoparticulate or quantum-sized CdS (Q-CdS) can be tuned by changing or controlling particle size without...

N2P n T

Figure 5.1 The 2p molecular orbitals of the dioxygen molecule. Electron spins in the HOMO states for ground-state molecular oxygen are compared to spin-paired singlet oxygen and the one-electron reduction product, superoxide. symmetry constraints, a kinetically favorable reaction occurs when the reacting molecules have the same spin state. As a consequence, triplet-state oxygen,3O2, is unlikely to be highly reactive with a singlet-state molecule such as propane, CH3CH2CH3, due to the symmetry...

Nanomaterials for Groundwater Remediation

Lowry Carnegie Mellon University, Pittsburgh, Pennsylvania, USA Contamination of subsurface soil and groundwater by organic and inorganic contaminants is an extensive and vexing environmental problem that stands to benefit from nanotechnology. The EPA reports that contamination by chlorinated organic pollutants such as trichloroethylene (TCE), and heavy metals such as lead and hexavalent chromium are primary concerns at Superfund National Priorities List sites, which are the most...

Forces Acting On A Particle

Forces Acting Particle

Figure 7.20 Travel distance (meters) in a homogeneous porous medium as a function of particle size (v 0.02 cm sec-1). Three different attachment efficiencies are assumed accounting for unfavorable and favorable deposition conditions. initial particle concentration no to a concentration of n.) Plotting reciprocal A as a function of particle size (Figure 7.20), it is evident that even for nanoparticles with low attachment efficiencies, the characteristic distance to which they will travel in a...

Fullerene Photochemistry and ROS Generation Potential

Similar to the cases of the metal oxide and sulfide semiconductors, the photochemical properties of fullerenes can be viewed in the context of excitation of electrons across a bandgap. For example, the bandgap of pure C60 has been reported to be 2.3 eV, which is comparable to that of iron oxide polymorphs (Table 5.3). The bandgap for carbon nanotubes (CNTs) depends on its chirality and is inversely proportional to the diameter of the nanotube. In the case of ROS generation by fullerenes, they...

Contents

Part I Nanotechnology as a Tool for Sustainability Chapter 1. Nanotechnology and the Environment Mark R. Wiesner and Jean-Yves Bottero 3 Nano-convergence and Environmental Engineering 4 Origin and Organization of this Book 6 Chapter 2. Nanotechnology and Our Energy Challenge Wade Adams and Amy Myers Jaffe 15 Nanotechnology and Renewable Energy 19 Chapter 3. Nanomaterials Fabrication Jean-Pierre Jolivet and Andrew R. Barron 29 Specificity and Requirements in the Fabrication Methods of...

References

G. 1996 . Reduction of Nitro Aromatic Compounds by Zero-Valent Iron Metal. Environmental Science amp Technology, 30 1 , 153-160. Annable, M. D., Jawitz, J. W., Rao, P. S. C., Dai, D. P., Kim, H., and Wood, A. L. 1998 . Field Evaluation of Interfacial and Partitioning Tracers for Characterization of Effective NAPL-Water Contact Areas. Ground Water, 36, 495-503. Baumann, T., Keller, A. A., Auset-Vallejo, M., and Lowry, G. V. Micromodel Study of Transport Issues...

Info

Alkoxides of low electronegative elements have to be handled with care, under dry atmosphere, because traces of water can be enough to provoke precipitation. By comparison, alkoxides of very electronegative elements such as O P OEt 3 2.11 are quite inert and do not react with water in normal conditions. The reactivity of metal alkoxides is also very sensitive to the steric hindrance of the alkoxy groups. It strongly decreases when the size of the OR group increases. For instance, the rate...

Reactivity Fate and Lifetime

Nanoparticles can sequester groundwater contaminants via adsorption or complexation , making them immobile, or can degrade or transform them to innocuous compounds. Contaminant transformations by nano-iron, which is a strong reductant, are typically redox reactions. When the oxidant or reductant is the nanoparticle itself, it is considered a reactive nanoparticle Figure 8.2 . A good example of a reactive nanoparticle is TCE dechlorination by nanoiron. Oxidation of Fe0 in the particle provides...

Nanosensors Sensitive Probes for the Biodetection of ROS

In the context of testing, a nanobiosensor can involve a biological molecule that serves as a detector, linker, or mediator, and nanoelectrodes. Various components can be equated with the electronic elements of a sensor, as every component has to transduce the signal generated at the source biomolecule to the detector electrode Figure 6.2 . Consequently, NADH peroxidase Multi-histidine peptide AuNP Figure 6.2 Nanobiosensor assembly based on the atomic coordinates of the NADH peroxidase and MHP...

List of Acronyms and Symbols

CMC carboxy methylcellulose COC chlorinated organic compounds DCA dichloroethane DCE dichloroethene DIRB dissimilatory iron reducing bacteria DLVO Deraguin-Landau-Verwey-Overbeek DNAPL dense nonaqueous phase liquid dp particle diameter L e electron EDL electrostatic double layer EDTA ethylenediaminetetraacetic acid Fe B nanoiron synthesized from reduction of dissolved iron using sodium borohydride kH2obs observed rate constant for H2 evolution from nanoiron corrosion in water t_1 KOW...

Paradigms for Assessing NM Toxicity

Air pollution and mineral dust particles have been implicated in a number of adverse biological effects and disease outcomes. Major disease outcomes include the exacerbation of airway inflammation, asthma, interstitial pulmonary fibrosis, atherosclerosis, ischemic cardiovascular events, and cardiac arrhythmias. Fortunately, no clinically recognizable disease outcomes have so far been reported for manufactured NM to date. Although a household-cleaning product Magic Nano was recently implicated...

A

Bingel Reaction

Figure 3.38 Strain release after addition of addend A to a pyra-midalized carbon of C60. in C60 is sp2'278 and a fractional s character of 0.085, which results in the orbitals extending further beyond the outer surface than into the interior of fullerene. This analysis implies that fullerenes, especially C60, are fairly electronegative molecules as well as having the low lying orbital with considerable s character. Indeed, the reactivity of fullerene can be considered as a fairly localized, but...

O O

Figure 3.50 Catalytic oxidation and de-epoxidation of SWNTs. the fluorinated 10,10 SWNTs with C2F stoichiometry performed by using DFT revealed 1,2 addition is more energetically preferable than 1,4 addition. Recently, solid-state 13C NMR has demonstrated the predominance of 1,2 addition and provided accurate quantification of the C F ratio 212 . F-SWNTs make highly flexible synthons and subsequent elaboration has been performed with organo lithium, Grignard reagents, and amines 213-216 ....