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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
151

Destruction of polycyclic aromatic hydrocarbons (PAH's) and aliphatic hydrocarbons in soil using ball milling

Magoha, Happy Steven Unknown Date (has links)
This study involves the use of ball mill as a mechanochemical reactor in the destruction of environmental contaminants. Although the technology has the potential to be used for a wide range of organic contaminants, this study focused on polycyclic aromatic hydrocarbons (PAH's) and aliphatic hydrocarbons. There are different methods for the remediation of the environmental contaminants such as biological, chemical and thermal techniques, most of which are costly. The ball mill is less costly as it involves low technology and little or no other chemicals seem to be needed to give complete destruction of the substances investigated. The mill is relatively easy to construct and can be made in different designs and dimensions to fit its intended purpose i.e. they can range from a laboratory scale to a very large industrial mill for the continuous processing of tonnes of material at a time. The process can be sealed so pollution from the mill is easy to control. In this study two classes of environmental contaminants were investigated. PAH's are common by-products of combustion and are found as contaminants in many soils. The other compounds investigated were the larger aliphatic hydrocarbons. These were chosen as being representative of the evaporated residues from fuel spills or leaks. A laboratory scale centrifugal ball mill with capacity of approximately 200 g was used for the study. The PAH's investigated were naphthalene, anthracene and phenanthrene. The aliphatic hydrocarbons n-eicosane and n-octacosane were used as the model compounds for hydrocarbon residues. Different soil types (scoria, clay soil, silica sand and slag) were spiked with a known amount of these contaminants. The ball milling was done under different milling conditions i.e. with different ball ratio and with different milling duration. In some experiments there was an addition of materials such as a potential free radical trap or metals to investigate the effect on the mechanochemical reaction. The samples were analysed using an ultrasonic extraction method (EPA METHOD 3550C) with GC and GC-MS analysis of the extract for the quantification of the residual contaminant in the soil and identification of possible secondary products and reaction intermediates. It was found that high destruction efficiency was achieved using milling times of between 120 and 150 minutes and high ball to soil ratios for example 7:1 ball mass to soil mass ratio. Also it was found that different type of soil had an influence on the mechanochemical reaction. A silica matrix was found to have a better destruction rate compared to scoria and clay soil. It was also found that the PAH compounds were more rapidly destroyed by ball milling than were aliphatic hydrocarbons. The addition of BHT was found to reduce destruction rate of both PAH's and aliphatic hydrocarbons. This suggests the mechanism of destruction may involve a free radical mechanism. Aluminium metal was observed to have no significant effect in the destruction. The presence of lubricants such as waxes in the contaminated soil appeared to inhibit the mechanochemical reaction although the mechanism is still uncertain. From this study it was concluded that, the ball mill has considerable potential as an effective, low cost method for the destruction of certain environmental contaminants.
152

The biosynthesis of ravidomycin /

Keyes, Robert F., January 1989 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1989. / Vita. Abstract. Includes bibliographical references (leaves 69-71). Also available via the Internet.
153

Adsorption of simple molecules on graphite: A computer simulation study.

Moller, Michael Allan. Klein, Michael L. Unknown Date (has links)
Thesis (Ph. D.)--McMaster University (Canada), 1988. / Source: Dissertation Abstracts International, Volume: 49-11, Section: B, page: 4838. Supervisor: Michael L. Klein.
154

Thermo-oxidative removal of codeposits from DIII-D and JET tokamak tiles.

Ochoukov, Roman. January 2006 (has links)
Thesis (M.A. Sc.)--University of Toronto, 2006. / Source: Masters Abstracts International, Volume: 44-06, page: 2988.
155

Porphyrin-catalyzed oxidation of trichlorophenol /

Hasan, Saleem. January 1994 (has links)
Thesis (Ph.D.)--University of Tulsa, 1994. / Includes bibliographical references (leaves 219-228).
156

Role of hydrocarbon structures in gas solvent + hydrocarbon multiphase equilibria /

Hong, Seung-pyo. January 1992 (has links)
Thesis (Ph.D.)--University of Tulsa, 1992. / Bibliography: leaves 119-124.
157

Impact of a prescribed forest burn on ambient hydrocarbon levels in Louisiana

Velugula, Hemakumar. January 2003 (has links)
Thesis (M.S.)--Ohio University, Novmeber, 2003. / Title from PDF t.p. Includes bibliographical references (leaves 64-66).
158

Structures and reactions of polycyclic compounds /

Walker, Ian Saville. January 1955 (has links) (PDF)
Thesis (Ph.D.)---University of Adelaide, 1955. / Typewritten copy.
159

Organo nickel and platinum chemistry at the edge of corannulene

Lee, Han Baek, January 2007 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed Dec. 27, 2007). Includes bibliographical references.
160

Raoult's law and the equilibrium vaporization of hydrocarbon mixtures

Rogers, Marvin Carson, Brown, George Granger, January 1929 (has links)
Thesis (Ph. D.)--University of Michigan, 1929. / Cover title. "By Marvin C. Rogers and Geo. Granger Brown."

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