Environmental Applications of Nanoscale and Microscale Reactive Metal Particles

Abstract Permeable reactive barrier (PRB) containing zero valent iron (ZVI), plaster and additives to make a porous composite structure was tested to remove an organic nitro compound as model pollutant. An aqueous solution of 4-nitroaniline (PNA) was passed through a porous plaster composite column and chemical degradation quantified by UV-Vis spectroscopy. PNA was reduced to p-phenylenediamine and the rate of the reduction was strongly related to ZVI amount, pollutant volume, and the contact rate with metal particles. The parameters could be controlled by reactor design and operation. The columns were made to test the materials for making precast plaster blocks containing ZVI. The results showed that such porous plaster blocks could be efficient as retaining walls for environmental applications.

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Profile TEM observations of small UHV-grown palladium particles

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100089445 ◽

1991 ◽

Vol 49 ◽

pp. 1026-1027

Author(s):

D.L. Neiman ◽

G. Fuchs ◽

H.R. Poppa

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Metal Clusters ◽

Metal Particles ◽

Reactive Metal ◽

Oxide Supports ◽

Transmission Electron ◽

Heated Wire ◽

Palladium Particles ◽

Reactive Metals

Projectional Transmission Electron Microscopy (TEM) of vapor-grown metal clusters on oxide supports is an extensively-used technique. An important limitation to this technique is the difficulty in determining the particle shape parallel to the electron beam. Use of submicron-sized “micro-supports” such as microcubes (MgO) and microspheres (TiO2 and Al2O3) allows the metal particles to be seen directly in profile. This has been shown for nonreactive deposits such Au, but few results for reactive metals have been published (notably Pd/MgO2 and Rh/TiO2). We present results for the system Pd/Al2O3, which show limitations to the use of profile TEM in the study of reactive metal deposits.Plasma-grown microspheres of A12O3 were supended in cthanol and then applied to commercial holey carbon grids. The grid were inserted into an ultrahigh vacuum (p<2x10-7 Pa) system for Pd deposition. Palladium was deposited from a heated-wire source at a rate R = 0.03nm/min. Sample temperature during deposition was 573K.

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Ignition of highly reactive metal particles

Doklady Physical Chemistry ◽

10.1134/s0012501616080029 ◽

2016 ◽

Vol 469 (2) ◽

pp. 117-120

Author(s):

A. P. Aldushin ◽

M. I. Alymov ◽

P. M. Krishenik ◽

S. A. Rogachev

Keyword(s):

Metal Particles ◽

Reactive Metal

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Electron Microscopy of the Shape of Small Metal Particles

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100079024 ◽

1977 ◽

Vol 35 ◽

pp. 300-301

Author(s):

M. Jose Yacaman

Keyword(s):

Electron Microscopy ◽

Metal Particle ◽

Field Experiments ◽

Size Range ◽

Dark Field ◽

Metal Particles ◽

Bragg Condition ◽

Crystal Particle ◽

Small Metal Particle ◽

Small Metal Particles

In the Study of small metal particles the shape is a very Important parameter. Using electron microscopy Ino and Owaga(l) have studied the shape of twinned particles of gold. In that work electron diffraction and contrast (dark field) experiments were used to produce models of a crystal particle. In this work we report a method which can give direct information about the shape of an small metal particle in the amstrong- size range with high resolution. The diffraction pattern of a sample containing small metal particles contains in general several systematic and non- systematic reflections and a two-beam condition can not be used in practice. However a N-beam condition produces a reduced extinction distance. On the other hand if a beam is out of the bragg condition the effective extinction distance is even more reduced.

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Structure and composition of metal particles in Pt-Sn/Al2O3 bimetallic catalysts

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100174527 ◽

1990 ◽

Vol 48 (4) ◽

pp. 278-279

Author(s):

A. Sachdev ◽

J. Schwank

Keyword(s):

Bimetallic Catalysts ◽

Bimetallic Catalyst ◽

Size Structure ◽

High Surface ◽

High Surface Area ◽

Metal Particles ◽

Alloy Formation ◽

Particle Size Range ◽

Oxide Supports ◽

Petroleum Fractions

Platinum - tin bimetallic catalysts have been primarily utilized in the chemical industry in the catalytic reforming of petroleum fractions. In this process the naphtha feedstock is converted to hydrocarbons with higher octane numbers and high anti-knock qualities. Most of these catalysts contain small metal particles or crystallites supported on high surface area insulating oxide supports. The determination of the structure and composition of these particles is crucial to the understanding of the catalytic behavior. In a bimetallic catalyst it is important to know how the two metals are distributed within the particle size range and in what way the addition of a second metal affects the size, structure and composition of the metal particles. An added complication in the Pt-Sn system is the possibility of alloy formation between the two elements for all atomic ratios.

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Investigation of cluster layers of small netal particles by TEM, SEM, EELS and by photoacoustic spectroscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100174382 ◽

1990 ◽

Vol 48 (4) ◽

pp. 250-251

Author(s):

H. Seiler ◽

U. Haas ◽

K.H. Körtje

Keyword(s):

Bulk Material ◽

High Vacuum ◽

Optical Methods ◽

Metal Particles ◽

Silver Particles ◽

Low Loss ◽

Plasmon Excitation ◽

First Results ◽

Diffraction Patterns ◽

Small Metal Particles

The physical properties of small metal particles reveal an intermediate position between atomic and bulk material. Especially Ag has shown pronounced size effects. We compared silver layers evaporated in high vacuum with cluster layers of small silver particles, evaporated in N2 at a pressure of about 102 Pa. The investigations were performed by electron optical methods (TEM, SEM, EELS) and by Photoacoustic (PA) Spectroscopy (gas-microphone detection).The observation of cluster layers with TEM and high resolution SEM show small silver particles with diameters of about 50 nm (Fig. 1 and Figure 2, respectively). The electron diffraction patterns of homogeneous Ag layers and of cluster layers are similar, whereas the low loss EELS spectra due to plasmon excitation are quite different. Fig. 3 and Figure 4 show first results of EELS spectra of a cluster layer of small silver particles on carbon foil and of a homogeneous Ag layer, respectively.

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