M. Tech. Chemical Engineering. / Discusses the scope of this research study composes of three interactive steps. The first step involves the design of the specific zeolite system (ZSM-5) and the set-up of an autoclave reactor for the hydrothermal synthesis of this and other zeolites and nano materials, then the oxidation catalyst (TS-1) development, i.e. the substitution of aluminium with titanium in the zeolite framework, and finally the formulation and preparation of the isomorphous Silicalite zeolite by omitting the aluminium in the synthesis. And further, set-up of suitable equipments and apparatus for the catalytic testing of the Titanium Silicalite-1 in the oxidation reaction of phenol as the test reaction. Therefore, the overall objectives of this research are: set up an autoclave reactor for the hydrothermal synthesis, formulation of a synthesis recipe for MFI family of catalysts in the laboratory, synthesis of ZSM-5, Silicalite-1, and TS-1 zeolites catalysts in the laboratory, characterization and optimization of the of catalysts listed above, testing the Ti-Silicalite catalyst in the oxidation reaction of phenol with hydrogen peroxide, as the oxidant, set up analytical system (Gas Chromatography, ASS) for analysis of catalyst performance in the oxidation reaction, Evaluate the conversion of the reaction and the selectivity of the individual catalysts reaction Evaluate the conversion of the reaction and the selectivity of the individual catalysts reaction and verify results obtained and compare with systems described in the literature.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

The work presented in this thesis describes the occurrence and properties of two multicopper oxidases derived from lichens. Despite numerous data on laccases and tyrosinases in fungi and flowering plants, this is the first report of the occurrence of these enzymes in lichenized ascomycetes. Extracellular laccase and tyrosinase activity was measured in 50 species of lichens from different taxonomic groupings and contrasting habitats. Out of 27 species tested from suborder Peltigerineae, all displayed laccase and tyrosinase activity that correlated to each other, while activity was absent in species tested from other lichen groups. Identification of the enzymes as laccases and tyrosinases was confirmed by the ability of lichen thalli or leachates to readily metabolize substrates such as 2,2’-azino(bis-3-ethylbenzthiazoline-6-sulfonate) (ABTS), syringaldazine and o-tolidine in case of laccase and L-dihydroxyphenylalanine (L-DOPA), Ltyrosine and epinephrine in case of tyrosinase in the absence of hydrogen peroxide. The activities of both enzymes were highly sensitive to cyanide and azide, and tyrosinase activity was sensitive to hexylresorcinol. Laccase activity had typical pH and temperature optima and an absorption spectrum with a peak at 614 nm. Tyrosinases could be activated by sodium dodecyl sulphate (SDS) and had typical tyrosinase molecular masses of approx. 60 kDa. The diversity of laccase isoforms in 20 lichen species from suborder Peltigerineae was investigated. The molecular masses of the active forms of most laccases varied between 135 and 190 kDa, although some lichens within the family Peltigeraceae had laccases with higher masses, typically varying from 200 to over 350 kDa. Most species contained one oligomeric laccase isoform. Desiccation and wounding stimulated laccase activity, while only wounding stimulated tyrosinase activity. The ability of laccases to decolorize dye is a classic attribute of laccases, and one with biotechnological potential. The ability of eight lichen species to decolourize different types of dyes was therefore tested. Interestingly, results showed that not only species belonging to suborder Peltigerineae but also species from other lichen group effectively decolourised dyes after 48 h suggesting that other oxidases appear to have ability to decolorize. Hopefully, our work could contribute to the better knowledge and application of lichen multicopper oxidases. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (p. 134-140).

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2008. / Title from title screen (site viewed Mar. 31, 2009). PDF text: x, 186 p. : ill. ; 8 Mb. UMI publication number: AAT 3331460. Includes bibliographical references. Also available in microfilm and microfiche formats.

Thesis (Ph. D.)--Ohio State University, 2008. / Title from first page of PDF file. Includes bibliographical references (p. 119-127).

Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2009. / Committee Chair: Bridgette Barry; Committee Member: El-Sayed, Mostafa; Committee Member: Fahrni, Christoph; Committee Member: Kröger, Nils; Committee Member: McCarty, Nael. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (doctoral)--Lund University, 1998. / Includes bibliographical references.

Title from PDF of title page (University of Missouri--Columbia, viewed on March 2, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dr. Kent S. Gates, Dissertation Supervisor. Vita. Includes bibliographical references.

Thesis (Ph.D.)--McMaster University, 2004. / Advisor: G. J. Schrobilgen. Includes bibliographical references (leaves 333-352). Also available online.