To see the other types of publications on this topic, follow the link: Oxidation.
Dissertations / Theses on the topic 'Oxidation'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Oxidation.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
S, Suresh. "Studies On Oxidation Of Benzylidene Derivatives." Thesis, Indian Institute of Science, 1994. https://etd.iisc.ac.in/handle/2005/151.
Full textAbstract:
Perfumery compounds isoeugenol and isosafrole can be oxidized to their aldehydes, vanillin and heliotropin respectively. The aldehydes obtained are very useful and commercially valuable products. Apart from their importance as perfumery compounds, they form important intermediates in the Pharmaceuticals and pesticide industries.
Liquid phase oxidation of isosafrole using different oxidizing agents were tried. Sodium dichromate as oxidizing agent in aqueous acetic acid was found to be most suitable because of its higher yields and mild reaction conditions. This reaction was taken up for detailed study.
Since the kinetic study of dichromate oxidation in aqueous acetic acid medium of isosafrole has not been mentioned in the literature, various parameters like isosafrole, dichromate and acetic acid concentrations were studied. The experiments were conducted at different temperatures to estimate the activation energy of the reaction. The effect of added salts like manganese sulfate, manganese acetate and cobaltous acetate has also been studied. For all the experiments the change in isosafrole concentration was observed.
The rate of reaction increases with increase in isosafrole concentration. The order of the reaction with respect to isosafrole concentration is found to be one. The rate of reaction increases with increase in initial sodium dichromate concentration. The reaction is found to be half order in dichromate ion concentration.
The rate of reaction increases with increase in acetic acid concentration with an order two. The atmospheric oxygen does not affect the reaction rate suggests that the reaction may not be free radical reaction.
The rate of reaction increases with increase in temperature. The activation energy was found to be equal to 14.59 kcal/mol.
2
S, Suresh. "Studies On Oxidation Of Benzylidene Derivatives." Thesis, Indian Institute of Science, 1994. http://hdl.handle.net/2005/151.
Full textAbstract:
Perfumery compounds isoeugenol and isosafrole can be oxidized to their aldehydes, vanillin and heliotropin respectively. The aldehydes obtained are very useful and commercially valuable products. Apart from their importance as perfumery compounds, they form important intermediates in the Pharmaceuticals and pesticide industries.
Liquid phase oxidation of isosafrole using different oxidizing agents were tried. Sodium dichromate as oxidizing agent in aqueous acetic acid was found to be most suitable because of its higher yields and mild reaction conditions. This reaction was taken up for detailed study.
Since the kinetic study of dichromate oxidation in aqueous acetic acid medium of isosafrole has not been mentioned in the literature, various parameters like isosafrole, dichromate and acetic acid concentrations were studied. The experiments were conducted at different temperatures to estimate the activation energy of the reaction. The effect of added salts like manganese sulfate, manganese acetate and cobaltous acetate has also been studied. For all the experiments the change in isosafrole concentration was observed.
The rate of reaction increases with increase in isosafrole concentration. The order of the reaction with respect to isosafrole concentration is found to be one. The rate of reaction increases with increase in initial sodium dichromate concentration. The reaction is found to be half order in dichromate ion concentration.
The rate of reaction increases with increase in acetic acid concentration with an order two. The atmospheric oxygen does not affect the reaction rate suggests that the reaction may not be free radical reaction.
The rate of reaction increases with increase in temperature. The activation energy was found to be equal to 14.59 kcal/mol.
3
Tran, Lien-Hoa. "Biomimetic Reactions : Water Oxidation and Aerobic Oxidation." Doctoral thesis, Stockholm : Department of Organic Chemistry, Stockholm University, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-26259.
Full text
4
Brandt, Cirsten Maja. "Oxidation und epitaktische Oxidation von Nickel und Nickellegierungen." [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=966154002.
Full text
5
Davies, Aled Mathew. "Selective oxidation and oxidative dehydrogenation reactions using niobium based catalysts." Thesis, Cardiff University, 2009. http://orca.cf.ac.uk/54882/.
Full textAbstract:
The selective oxidation of methanol to formaldehyde, the oxidative dehydrogenation of ethane and the oxidative dehydrogenation of propane have been investigated using niobium based catalysts. It has been shown that niobium oxides prepared by different methods show in general a low conversion of reactant in all probe reactions investigated. However, high selectivity to the desired products are maintained (i.e. formaldehyde, ethylene and propene) at elevated temperatures. The introduction of phosphorus into niobium based catalysts enhanced the catalytic performance of the catalyst The aim was to maintain a high selectivity of desirable products whilst increasing conversion. Two sets on niobium and phosphorus based catalysts were investigated. The first set of catalyst was niobium oxide phosphates, NbOPC>4, prepared from a method which was analogous to VPO work. Catalytic testing of the niobium oxide phosphates showed an increased conversion in both methanol oxidation and ethane oxidative dehydrogenation. However, there was little effect in using niobium oxide phosphates for the oxidative dehydrogenation of propane. Comparing niobium oxide phosphates to niobium oxides, the conversion doubled with respect to oxidative dehydrogenation of ethane and increased 18-fold with respect to methanol oxidation. The second set of niobium and phosphorus based catalysts were niobium phosphates, NbPOs. These were prepared from the reduction of niobium oxide phosphates. Catalytic testing showed an increased conversion in both methanol oxidation and ethane oxidative dehydrogenation. This is the first time that niobium phosphates and oxyphosphates have been investigated as catalysts and they demonstrate appreciable activity for a range of selective oxidation reactions.
6
Cox, Simon Peter. "Iron oxidation and mineral oxidation by moderately thermophilic bacteria." Thesis, University of Warwick, 1992. http://wrap.warwick.ac.uk/109481/.
Full textAbstract:
The microbial oxidation of minerals is a commercially important process. Until comparatively recently only one organism capable of mineral oxidation has been extensively studied - Thiobacillus ferrooxidans. Several new, potentially commercially important isolates were studied in comparison with T.ferrooxidans. This was done with regard to their iron and sulphur oxidation systems, which are vital to the process of mineral solubilisation, and their ability to solubilise the minerals pyrite or chalcopyrite. The study of the latter was undertaken with particular reference to mixed culture leaching. The effect of growth substrate history on iron and sulphur oxidation varied between organisms. In particular, strain BC1 lost very little of its iron or sulphur oxidation capacity whether it was grown on either substrate. Conversely, the oxidation systems of T.ferrooxidans were directly influenced by growth substrate. SDS PAGE analysis and optical spectroscopy of T.ferrooxidans and strains BC1, LM2 and TH3 were used to investigate iron and sulphur oxidation systems and principally to indicate target components of these systems for further detailed study. Further study of the iron oxidation system in strain BC1 showed that there was only one major chromophore, a membrane bound cytochrome aa_. This had absorption peaks at 443 nm, 560 nm and 604.5 nm. Spectra run at 77°K indicated a shoulder on the Soret peak at approximately 450 nm. Extensive investigation into the effect on the cytochrome aa_ of various detergents culminated in the solubilisation from the membrane of the terminal oxidase in an intact form. This allowed the mid-point redox potential of this cytochrome to be determined as +524 mV. The mid-point redox potentials of T.ferrooxidans cytochrome £ and fi. were determined as +317 mV and +497 mV respectively. SDS PAGE analysis indicated two proteins that could be involved in growth on ferrous iron, at 27 kD and 31 kD. One or both of these proteins appeared to contain very high levels of iron. High levels of iron were also found in fractions from column chromatography which contained cytochrome aa_. Mineral oxidation studies showed that there was a slight increase in the rate of leaching of chalcopyrite in mixed cultures of strain BC1 and strain BC13 when compared to a pure culture of strain BC1, when the organisms where grown in shake flasks. In airlift reactor leaching of chalcopyrite the addition of strain BC13 to strain BC1 had several major effects. The pH in the mixed culture reactor was kept far more constant. Despite this, the leaching of copper from the mineral was not significantly altered in the mixed culture. However, a notable phenomenon in this mixed culture of strain BC1 and strain BC13 was the apparent reduction of the specific iron oxidation capacity of strain BC1 in comparison with its activity in pure culture.
7
Dobson, P. "The electrophilic halogenation, prevost oxidation and peroxydisulphate oxidation of alkenes." Thesis, University of York, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377280.
Full text
8
Kim, Jun Mo. "Exploring the chemistry of bilirubin oxidation end products." Thesis, Griffith University, 2021. http://hdl.handle.net/10072/404159.
Full textAbstract:
Bilirubin is an endogenous molecule that is formed from the degradation of haem when senescent red blood cells have been transported to the liver, kidneys and spleen. Since its discovery, it has been thought of as a waste product that required excretion upon degradation due to accumulation leading to detrimental health conditions such as neonatal hyperbilirubinaemia and kernicterus. As such, the primary research focus on bilirubin has been on developing treatment protocols for reducing elevated levels of bilirubin, as well as optimising and developing more sensitive, robust and streamlined methods of measuring serum and urine bilirubin levels. However, there has since been a change in focus whereby recent research has demonstrated the antioxidative activity of bilirubin and has led to the postulation that it also has a physiological role as a protective cellular antioxidant, producing bilirubin oxidation by-products as a result of scavenging reactive oxygen and nitrogen species.
There is a need for identifying and clarifying this developing area of research that also suggests that bilirubin oxidation end products could be associated with a variety of health conditions. This study commenced with a scoping review to distinguish the different types of bilirubin oxidation end products in the literature, for the purpose of conducting further detailed literature reviews, identifying gaps and informing the direction of experimental work for the thesis. The scoping review identified two pyrrole-containing oxidative by-products of bilirubin as biotripyrrins, biopyrrins, or bilirubin oxidative metabolites (BOMs) and bilirubin oxidation products (BOXes). A third pyrrole-containing compound was identified that has been associated with mental illness and oxidative stress, with speculation on its origin. Due to the structural similarities shared with this compound and BOMs and BOXes, it was considered important for further literature review. Two broad themes emerged from the scoping review as a focus for the subsequent reviews on the three groups of pyrrole compounds: (i) elucidation, characterisation and chemical synthesis of bilirubin oxidation end products, (ii) and proposed clinical application or pathophysiology for the bilirubin oxidative end products, including both human and animal studies.
It was found that BOMs were serendipitously discovered when researchers were developing an enzyme-linked immunosorbent assay (ELISA) to detect total and unconjugated bilirubin. This led to the characterisation of these bilirubin metabolites that were hypothesised to result from conditions of oxidative stress. A number of clinical studies reported elevated levels of these metabolites for a wide variety of unrelated health conditions, particularly for cardiovascular and mental health conditions.
The findings from the literature review conducted on BOXes identified that these oxidised forms of bilirubin have been speculated as a causative agent of vasospasm in patients suffering from subarachnoid haemorrhage (SAH). There has been a focus on identifying the causes of vasospasm in patients with SAH due to the condition being described as clinically frustrating and challenging to manage. Initial reports on BOXes identified these compounds in the cerebral spinal fluid (CSF) of SAH patients and researchers were able to characterise compounds related to bilirubin albeit at poor yields. A few reports that have investigated these compounds in in vitro and in vivo models corroborated the earlier findings however the low yields acquired from initial methods of synthesis reflected the lack of reports on the mode of action of BOXes. Recent publications have provided insight into the syntheses of these compounds at relatively high yields.
The final literature review was conducted on urine pyrroles that have been the subject of considerable controversy, primarily relating to their chemical structure, as well as their role in mental health, which is not recognised or accepted by mainstream medicine. Urine pyrroles were originally identified in the 1960’s in patients with schizophrenia due to the purple colour observed when their urine samples reacted positively to Ehrlich’s reagent hence the name ‘Mauve factor’. Considerable efforts in identifying the compounds through qualitative and semiquantitative methods showed that the compounds were highly unstable hindering the characterisation and methods of syntheses. Due to their unstable nature, misidentifications were frequently reported in the literature, and together with their undetermined pathophysiological origin, compounded the controversy. Despite the unclear nature of the exact biochemical mechanisms of urine pyrroles, contemporary treatment and diagnosis of ‘pyrrole disorder’ or ‘pyroluria’ is gaining popularity, highlighting the importance of identifying the exact chemical structures as well as investigating the pathophysiology behind this elusive condition.
The literature reviews provided the impetus for the direction of the experimental work. A number of intermediate compounds were derived from a series of photooxidation reactions using 2,4-dimethyl-3-ethyl-pyrrole. This provided insight into the solvent conditions required for these intermediates to be isolated, with preliminary results showing close structural similarities to compounds shown in reports originally investigating urine pyrroles and more recently in the characterisation of BOXes. Further, two intermediate compounds that previously have not been reported in the literature were synthesised through the photooxidation reactions. Both compounds followed similar methods of preparation and subsequent work-up with the distinction being the time of irradiation under ultraviolet light when in the presence of hydrogen peroxide (H2O2). One compound was irradiated for a period of over 96 hours before undergoing organic solvent work-up after being quenched with sodium hydrogen (NaOH) whereas the other novel compound was irradiated for a period of 48-72 hours. It was found that differing times in irradiation could provide insight into the dynamic system of these sensitive photooxidation reactions. Despite rigorous efforts in work-up and purification, the exploratory experiments in this study have shown that the compounds will readily interconvert into different compounds. This in turn directed the proceeding review and experimental work investigating the reactivity of the chemical trap para-dimethylaminobenzaldehyde, colloquially known as Ehrlich’s reagent, since a suitable chemical trapping agent would likely be needed for these highly reactive compounds.
The literature reviews revealed that specifically for BOM research, there were a lack of reports pertaining the baseline reference ranges when utilising the ELISA biopyrrin kits. Establishing reference ranges may allow for accurate comparisons with established clinical markers that could validate BOMs as a robust clinical tool. The findings from the literature review on BOXes literature review showed that a continuation of research to establish whether these compounds are the cause or result of vasospasm in patients with SAH could allow for future therapeutic development. The long history on urine pyrroles and its withstanding controversy shows a need for further research specifically determining whether zinc and vitamin B6 are able to form complexes with urines pyrroles. Finally, further experimental work will help clarify and understand the mechanisms relating to pyrrole-containing molecules for the investigation of other chemical trapping agents. Overall, this is the first study to identify and provide an in-depth review of bilirubin oxidation end products and their relationship to human health. The results collated from the scoping review, literature reviews and experimental work may provide a useful starting point to continue the early work on urine pyrroles from the 1970’s and support the developing research that is currently emerging for BOM and BOX compounds. Bilirubin oxidation end products may emerge as the missing link in the pathophysiology of a number of chronic health conditions.Thesis (Masters)
Master of Medical Research (MMedRes)
School of Pharmacy and Pharmac
Griffith Health
Full Text
9
Boyle, Sarah Ann. "Oxidation of toluene." Thesis, Queen's University Belfast, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387977.
Full text
10
Prouff, N. "Oxidation of metals." Thesis, University of Glasgow, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377188.
Full text
11
Beckett, Philip Ronald. "Amino acid oxidation." Thesis, University of Aberdeen, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.253828.
Full textAbstract:
The aim of the study was to determine the efficiency with which the carbon skeletons of essential amino acids are utilised by the pig when they are limiting in its diet. This requires the oxidation rate of an amino acid to be measured accurately using a tracer labelled with an isotope of carbon or hydrogen. The use of carbon labelled tracers requires the animal to be enclosed in a sealed chamber for the collection of CO2; to avoid this the use of [3H]-labelled tracers was investigated. The oxidation rates of [14C]-labelled tracers when the tracee was limiting and the animal's nitrogen intake was 2 g/kg0.75.d, showed that leucine was used with an efficiency of 0.88; for phenylalanine and histidine the efficiency was over 0.99. When the animal's nitrogen intake was reduced to 0.23 gN/kg0.75.d, and the limiting amino acid was removed entirely from the diet, the oxidation rates did not change significantly. The oxidation rates of [3H]amino acids were very variable compared to the [14C]amino acids and the techniques used were critically analysed. Three reasons were identified for the differences between the [14C]- and [3H]tracers. These were the measurement of tritiated water, the purity of the infused tracers and the position of the isotope in the labelled amino acid. The first two were solved by the adaption of techniques to the high accuracy required. The third reason was a problem of isotope becoming incorporated into synthetic pathways via exchange reactions. No amino acids were available labelled with a [3H] atom which would not be incorporated; therefore it was necessary to synthesise one. L-[33H]valine was chosen because a suitable precursor for its synthesis, L-[2,3-3H]valine was available and because L-[1-14C]valine was also available for comparison The L-[2,3-3H]valine was acetylated to produce N-acetyl-D, L-[3-3H]valine which was then hydrolysed by the stereospecific enzyme acylase I to yield N-acetyl-D-[3-3H]valine and L-[3-3H]valine. The products were separated using a cation exchange column and the L-[3-3H]valine was purified by paper chromatography. Contamination with D-[3-3H]valine was measured using D-amino acid oxidase and L-[2,3-3H]valine using L-amino acid oxidase. The oxidation rates of L-[1-14D]valine and L-[3-3H]valine were compared in the rat and the oxidation rate of L-[3-3H]valine was significantly higher. The experiment was repeated using L-[3-3H]valine synthesised by Amersham International plc. using the same method; the structure was established by NMR. In this case both tracers were oxidised at the same rate. The difference in the first experiment was therefore probably due to slight contamination of L-[3-3H]valine with L-[2,3-3H]valine, the tritium in position 2 being removed by reversible transamination of valine, i.e., not only during its oxidation. Finally, the two tracers were compared in the pig. It was found that the valine flux rates calculated from the two tracers were in closer agreement when a correction was made for infused D-labelled valine. Using the techniques developed throughout this work, L-[1-14C]valine and L-[3-3H]valine measured the same rate of valine oxidation. L-3-3H]valine was a more precise tracer of valine oxidation.
12
Ehlén, Anders. "Elevers vardagsföreställningar - oxidation." Thesis, Malmö högskola, Lärarutbildningen (LUT), 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-28085.
Full textAbstract:
Vardagsföreställning som fenomen är ett sätt för eleven att förklara ett skeende där eleven inte har full insikt och felaktiga idéer om naturvetenskapliga händelser kan därmed permanentas. I mitt examensarbete har jag undersökt elevers vardagsföreställningar kring begreppet oxidation samt om dessa föreställningar kan förändras till vetenskapligt korrekta begrepp. Genom enkätundersökning av elever ur låg-, mellan-, och högstadiet, gjorde jag ett studium över deras användande av begreppet oxidation och eventuella vardagsföreställningar kring det. Jag studerade även hur elevernas lärare bearbetade dessa vardagsföreställningar. Metoden jag använde var kvalitativa enskilda intervjuer. Elevers begreppsanvändande är inte en naturlig del vid inlärning, de växer fram med vidgade erfarenheter. Resultatet av enkät och intervju bidrog till min slutsats att det finns faktorer som påverkar elevers förståelse av begreppet oxidation. Dessa faktorer är av vikt för förståelsen hur elever bearbetar sina vardagsföreställningar. De faktorer som kom att påverka i min slutsats var inlärningsstilar, studiemiljö och interaktionen i studiegruppen.Everyday notion is a fenomena for pupills to explain a occurrence that doesn´t have a accepted sicence justification. The problem is that the pupills get the wrong idéa about the meaning of notion. Specially the term oxidation, had interested me.
13
Plant, Stuart D. "The response of human umbilical vein endothelial cells and blood platelets to modified NiTi surfaces." Thesis, University of Nottingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275630.
Full text
14
Wang, Wenzhong. "Mechanistic studies of flavoenzymes in fatty acid oxidation and oxidative protein folding." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 233 p, 2007. http://proquest.umi.com/pqdweb?did=1362529911&sid=3&Fmt=2&clientId=8331&RQT=309&VName=PQD.
Full text
15
To, Wai-pong, and 杜偉邦. "Transition metal catalysed photo-induced oxidative C-H bond functionalization and water oxidation." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hdl.handle.net/10722/193012.
Full textAbstract:
A series of cyclometalated gold(III) complexes with N-heterocyclic carbine (NHC) or alkynyl as auxiliary ligand were synthesized and characterized. Complexes [AuIII(R1
–C^N^C)(NHC)](OTf) and [AuIII(C^N^C)(C≡CR2)] (HC^N^CH = 2,6-di(naphthalene-2-yl)pyridine; R1 = H or 4-methoxyphenyl; R2 =aryl) are emissive in solution at room temperature with quantum yields in the range of 0.65–11.4% and lifetimes ranging from 98 to 506 s. [AuIII(4-(4-OMePh)–C^N^C)(NHC)](OTf) showed prominent photochemical properties. This complex effectively catalyses photo-induced oxidation of secondary amines (to the corresponding imines) and -functionalization of tertiary amines in good to excellent yields; it also acts as a photosensitizer for hydrogen generation in a water/acetonitrile mixture, producing more than 350 turnovers of hydrogen after 4 hours of irradiation.
Palladium(II) meso-tetrakis(pentafluorophenyl)porphyrin was found to be an efficient and robust catalyst for the photo-induced oxidative C–H bond functionalization reactions. Several kinds of -functionalized tertiary amines were obtained in good to excellent yields by irradiating a mixture of palladium(II) catalyst, corresponding tertiary amine and nucleophile under aerobic conditions. The nucleophiles for these reactions include cyanide, nitromethane, dimethyl malonate, diethyl phosphite and acetone. Two examples of novel intramolecularly cyclized amines were also described. Comparison of the UV-vis absorption spectra before and after reaction indicated that the palladium catalyst was highly robust. The practical potential of this catalyst was shown by the success in reactions at a low catalyst loading and on a large scale. The palladium(II) catalyst could also sensitize photo-induced oxidation of sulfide to sulfoxide and photo-induced hydrogen production in a water/acetonitrile mixture with up to 240 turnovers.
[FeIII(L-N4Me2)Cl2][FeCl4] (L-N4Me2 = N,N’-dimethyl-2,11-diaza[3,3] (2,6)pyridinophane) was demonstrated to be an active catalyst for water oxidation. When cerium ammonium nitrate (CAN) was used as the oxidant, the iron(III) catalyst oxidized water to oxygen with up to 93 turnovers after 30 minutes in 0.1 M nitric acid, whereas changing the oxidant to sodium periodate (NaIO4) resulted in only 44 turnovers of oxygen after 30 minutes. The mechanism of the reaction was explored by high resolution electrospray ionization mass spectrometry (ESI-MS), 18O labeling, UV-vis absorption spectroscopy, kinetic plots and DFT calculations. In the case of using CAN, an FeIV-oxo species was detected by ESI-MS and UV-vis absorption spectroscopy. The rate of oxygen evolution was found to be linearly dependent on both concentrations of catalyst and oxidant. 18O labeling studies confirmed that the origin of oxo ligands was from water and was irrespective of the choice of oxidant. This reaction was proposed to involve a coupling between an FeIV-oxo species and a hydroxocerium(IV) radical. In the case of using NaIO4, an FeV-dioxo species was detected by ESI-MS as a major species, and a small amount of FeIV-oxo species was detected by UV-vis absorption spectroscopy. As the rate of oxygen evolution was found to be linearly dependent on the concentration of catalyst only, the reaction was proposed to involve a cis-FeV-dioxo species. DFT calculations showed that the cis-FeV-dioxo species was capable of oxidizing water to oxygen through the formation of an [FeIII(L-N4Me2)(OO?)(OH)]+ intermediate.published_or_final_version
Chemistry
Doctoral
Doctor of Philosophy
16
Ogunlaja, Adeniyi Sunday. "Oxidative desulfurization of fuel oils-catalytic oxidation and adsorptive removal of organosulfur compounds." Thesis, Rhodes University, 2014. http://hdl.handle.net/10962/d1013152.
Full textAbstract:
The syntheses and evaluation of oxidovanadium(IV) complexes as catalysts for the oxidation of refractory organosulfur compounds in fuels is presented. The sulfones produced from the oxidation reaction were removed from fuel oils by employing molecularly imprinted polymers (MIPs). The oxidovanadium(IV) homogeneous catalyst, [V ͥ ͮ O(sal-HBPD)], as well as its heterogeneous polymer supported derivatives, poly[V ͥ ͮ O(sal-AHBPD)] and poly[V ͥ ͮ O(allylSB-co-EGDMA)], were synthesized and fully characterized by elemental analysis, FTIR, UV-Vis, XPS, AFM, SEM, BET and single crystal XRD for [V ͥ ͮ O(sal-HBPD)]. The MIPs were also characterized by elemental analysis, FTIR, SEM, EDX and BET. The catalyzed oxidation of fuel oil model sulfur compounds, thiophene (TH), benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT), was conducted under batch and continuous flow processes at 40°C by using tert-butylhydroperoxide (t-BuOOH) as oxidant. The continuous flow oxidation process presented the highest overall conversions and very high selectivity for sulfones. Maximum oxidation conversions of 71%, 89%, 99% and 88% was achieved for TH, BT, DBT and 4,6-DMDBT respectively when poly[V ͥ ͮ O(allylSB-co-EGDMA)] was employed at a flow-rate of 1 mL/h with over 90% sulfone selectivity. The process was further applied to the oxidation of hydro-treated diesel containing 385 ± 4.6 ppm of sulfur (mainly dibenzothiophene and dibenzothiophene derivatives), and this resulted to a high sulfur oxidation yield (> 99%), thus producing polar sulfones which are extractible by polar solid phase extractants. Adsorption of the polar sulfone compounds was carried-out by employing MIPs which were fabricated through the formation of recognition sites complementary to oxidized sulfur-containing compounds (sulfones) on electrospun polybenzimidazole (PBI) nanofibers, cross-linked chitosan microspheres and electrospun chitosan nanofibers. Adsorption of benzothiophene sulfone (BTO₂), dibenzothiophene sulfone (DBTO₂) and 4,6-dimethyldibenzothiophene sulfone (4,6-DMDBTO₂) on the various molecularly imprinted adsorbents presented a Freundlich (multi-layered) adsorption isotherm which indicated interaction of adsorbed organosulfur compounds. Maximum adsorption observed for BTO₂, DBTO₂ and 4,6-DMDBTO₂ respectively was 8.5 ± 0.6 mg/g, 7.0 ± 0.5 mg/g and 6.6 ± 0.7 mg/g when imprinted chitosan nanofibers were employed, 4.9 ± 0.5 mg/g, 4.2 ± 0.7 mg/g and 3.9 ± 0.6 mg/g on molecularly imprinted chitosan microspheres, and 28.5 ± 0.4 mg/g, 29.8 ± 2.2 mg/g and 20.1 ± 1.4 mg/g on molecularly imprinted PBI nanofibers. Application of electrospun chitosan nanofibers on oxidized hydro-treated diesel presented a sulfur removal capacity of 84%, leaving 62 ± 3.2 ppm S in the fuel, while imprinted PBI electrospun nanofibers displayed excellent sulfur removal, keeping sulfur in the fuel after the oxidation/adsorption below the determined limit of detection (LOD), which is 2.4 ppm S. The high level of sulfur removal displayed by imprinted PBI nanofibers was ascribed to hydrogen bonding effects, and π-π stacking between aromatic sulfone compounds and the benzimidazole ring which were confirmed by chemical modelling with density functional theory (DFT) as well as the imprinting effect. The home-made pressurized hot water extraction (PHWE) system was applied for extraction/desorption of sulfone compounds adsorbed on the PBI nanofibers at a flow rate of 1 mL/min and at 150°C with an applied pressure of 30 bars. Application of molecularly imprinted PBI nanofibers for the desulfurization of oxidized hydro-treated fuel showed potential for use in refining industries to reach ultra-low sulfur fuel level, which falls below the 10 ppm sulfur limit which is mandated by the environmental protection agency (EPA) from 2015.
17
Todorova, Mira. "Oxidation of Palladium surfaces." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=971639868.
Full text
18
Scowen, N. R. "Peroxidatic oxidation of luminol." Thesis, University of Newcastle upon Tyne, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384006.
Full text
19
Salama, Philippe. "Photocatalytic oxidation of NiEDTA." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103292.
Full textAbstract:
Metal-Ethylenediaminetetraacetic acid (EDTA) complexes are found in a variety of industrial process. The stability of the formed complexes makes these compounds often inert to conventional wastewater treatment systems. In this work, the photocatalytic oxidation of NiEDTA was investigated as a means of breaking up the chelated nickel. The studied variables included the light intensity rate, the catalyst (TiO2), oxygen and NiEDTA concentrations. Photocatalytic experiments showed that increasing the catalyst concentration (0.5-3.0 g/L) decreases the light penetration inside the reactor resulting in a decrease in the reaction rate. The effect of oxygen and NiEDTA concentration was shown to exhibit Langmuir-Hinshelwood type kinetics. Total organic carbon (TOC) did not show any significant mineralization of NiEDTA for all investigated conditions. As a result, the by-products of the reaction were measured and found to include ED3A (ethylenediaminetriacetic acid), N-N'-EDDA (ethylenediamindiaacetic acid), IDA (iminodiacetic acid), oxalic acid, oxamic acid, glyoxylic acid, formaldehyde, ammonia, nitrate and nitrite. ED3A was found to be the major by-product of the reaction and nitrogen added from NiEDTA was found to be released as ammonia nitrogen. Oxygen consumption experiments were demonstrated as an effective way to monitor the rate of the reaction through measurement of the electron oxygen utilization rate. Nickel precipitation experiments showed that some of the by-products of NiEDTA degradation formed complexes with nickel. Finally, a light distribution model was generated using a CFD software (Fluent 6.1.22). For the catalyst concentration range of 0.5 to 3.0 g/L, this model showed that all of the light energy supplied by a centered UV lamp is absorbed within a one centimeter distance. Using the local volumetric rate of energy absorption (LVREA) calculated from the model the rate of the reaction was expressed in terms of quantum yield. For experiments carried out with air the quantum yield showed that the degradation rate was limited from an insufficient oxygen supply for electron scavenging. Increasing the oxygen concentration to 0.60 mmole O2/L increased the quantum yield for the highest light intensity rate; however the quantum yield never reached an optimum value thus indicating that other limiting conditions exist.
20
Weeks, Simon A. "Anodes for methanol oxidation." Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.258023.
Full text
21
Kim, S. S. "Cobalt catalysed oxidation reactions." Thesis, University of East Anglia, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376060.
Full text
22
Kasuh, Takahiro. "Oxidation of mesophase pitch." Thesis, University of Newcastle Upon Tyne, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.346433.
Full text
23
Pourfarzam, Morteza. "#beta#-oxidation of dicarboxylates." Thesis, University of Newcastle Upon Tyne, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287139.
Full text
24
Richards, S. N. "Nitrous acid oxidation mechanisms." Thesis, University of Exeter, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379464.
Full text
25
Walker, M. D. "Oxidation at pentacovalent phosphorous." Thesis, City University London, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233199.
Full text
26
Sackville, Emma. "Molecular iridium oxidation catalysts." Thesis, University of Bath, 2018. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.767567.
Full textAbstract:
Oxidation reactions of both inorganic and organic substrates are among the most important chemical transformations, with application in sustainable chemistry and chemical synthesis. A library of half sandwich IrIII oxidation complexes with varying ligands were synthesised (54-78% yield) and fully characterised (NMR, UV-vis, crystal data), in order to investigate the effect on catalyst activity for water and C-H oxidation reactions. The electrochemical transition of IrIII to IrIV was investigated (cyclic voltammetry (CV)) and found to vary between ligand sets, such that alkyl substituted compounds had a lower midpoint potential than aryl substituted. Solution speciation under aqueous conditions was also investigated for all complexes (UV-vis spectroscopy), as well as investigation into catalyst activation by oxidative loss of the pentamethylcyclopentadienyl ligand (1H NMR, UV-vis spectroscopy).The catalytic activity for complexes Ir1-Ir7 was investigated for water oxidation with chemical oxidants, by oxygen evolution assays with a Clark electrode. All complexes evolved oxygen to some extent, with ligand effects causing significant variation in the rate of water oxidation (4.60 mM min-1 to 0.02 mM min-1 with sodium periodate in pure H2O). Mechanistic studies including H/D kinetic isotope effects and reaction progress kinetic analysis showed primary KIEs of 1.3-2.5, indicating O-H cleavage to be in the rate determining step. Determination of the catalyst order revealed an order in iridium of 0.5-0.6 for Ir1-Ir6 and 0.9 for Ir7, which was proposed to be due differences in the activecatalyst species for Ir7.The complexes were also tested for C-H oxidation performance and followed by 1H NMR. The reaction profiles for precatalysts Ir1-Ir7 all showed a plateau conversion with C-H oxidation, varying between 52% - 88%, which was attributed to a competition reaction with water oxidation. The varying ligands impart C-H/water oxidation selectivity onto the catalysts. The C-H oxidation scope was extended by investigations into the oxidation of several terpene-based compounds were also conducted (gas chromatography mass spectrometry, 1H NMR).Comparison of the water oxidation activity of the catalysts as driven by electrochemical potential (as followed by Clark electrode and chronoamperometry) exposed surprising trends that did not correlate with the chemical oxidant data and highlights the importance of reaction conditions when comparing water oxidation activity. Catalyst immobilisation was also attempted with a range of metal oxide supports (indium tin oxide on fluorine doped tin oxide glass, BiVO4, Fe2O3) and analysis of the resulting electrode assessed by CV. Fourier transform alternating current voltammetry (FTACV) was employed in order to investigate the oxidation state of the iridium during electrochemical water oxidation, revealing a clear [Ir] redox transition at the foot of the catalytic wave, proposed to be a key transition to the active catalytic species.
27
Meredith, Owain. "Passive catalytic soot oxidation." Thesis, Cardiff University, 2017. http://orca.cf.ac.uk/110463/.
Full textAbstract:
Increasingly stringent legislation limiting the emissions of particulate matter (commonly referred to as soot particulates) has led to the adoption of particulate filters in the exhausts of both diesel and gasoline passenger vehicles. While filters are highly effective at reducing these emissions, it is necessary to periodically remove trapped particulates in order to avoid their accumulation and the resulting loss of vehicle performance associated with backpressure build-up. An effective method of removing soot particulates is through combustion (oxidation) with the oxygen-containing species present in the atmosphere of the exhaust, however this is unattainable at the temperatures experienced under normal driving conditions. A catalyst able to lower the temperature of soot oxidation is therefore desirable in order to achieve passive regeneration of the filter. Previous studies have identified ceria, CeO2 as a promising soot oxidation catalyst due to its outstanding redox properties, and have shown that it can be enhanced by doping with various other metals. In this work, ceria-based catalysts have been prepared by the co-precipitation method. Ceria was doped with zirconium, lanthanum, praseodymium and neodymium in various ratios in order to enhance its catalytic properties. Each of these materials also contained alumina in order to improve their thermal stability. Of these materials, the most active for soot oxidation was found to be a CeO2-Nd2O3-Al2O3 catalyst prepared in a 7:3:10 molar ratio of Ce:Nd:Al and calcined at 750ºC under flowing air. This catalyst lowered the temperature at which soot oxidation reached its peak rate by over 100ºC. It was also demonstrated that the catalytic activity of these materials benefited considerably from the presence of alkali metals within their structure. The use of the ceria-based materials as supports by impregnating them with other species previously identified as active soot oxidation catalysts was also investigated, which resulted in a further lowering of the soot oxidation temperature. Structural characterisation of the materials was carried out by X-ray powder diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and surface area analysis (BET), while their redox properties were analysed by temperature-programmed reduction (TPR). The catalytic activity of the materials towards soot oxidation was investigated using thermogravimetric analysis (TGA).
28
Mounzer, Hamza. "Heterogeneous oxidation of alcohols." Thesis, University of Birmingham, 2009. http://etheses.bham.ac.uk//id/eprint/387/.
Full textAbstract:
The selective oxidation of alcohols is one of the most challenging reactions in green chemistry. While the current chemical industry uses organic and inorganic oxidants to produce carbonyl compounds, it is highly desirable to use a heterogeneous catalyst for the efficient oxidation of alcohols. The present research is focused on increasing the activity and selectivity towards the corresponding carbonyl of the heterogeneous oxidation for alcohols. The low activity of 5 wt.%Pt-1 wt. %Bi/Carbon for the oxidation of 2-octanol was investigated in a 500ml stirred tank reactor. The fast reaction rate drops dramatically from 0.23 M/hr to 0.006 M/hr after 15 minutes reaction time when heptane was used as solvent. Different possible causes such as overoxidation, leaching and poisoning were examined. It was found that the loss of high conversion rate was due to product adsorption and hence, different solvents were investigated. A mixture of 16-18% v/v dioxane in heptane was able to effectively regenerate active sites and allow a constant reaction rate of 0.07M/hr. The effects of temperature and pressure were also studied. Gas-liquid, liquid-solid and internal mass transfer effects were determined experimentally and semi-empirically. Six different Langmuir-Hinshelwood rate models were examined where a modified model based on Schuurman et al. (1992) was found to adequately describe the experimental data. The novel 2.5%Au-2.5%Pd/titania catalyst was investigated for the oxidation of benzyl alcohol. Different parameters such as catalyst oxidation state, pressure and stirrer design were studied to increase the activity and selectivity of the catalyst. The selectivity was shown to be highly dependent on the oxygen concentration. Therefore, the pressure, temperature, catalyst treatment were optimised and the reactor configuration was re-designed to enhance oxygen transport to the catalyst. While the conversion rate was unaffected by the oxygen concentration, the catalyst pre-treatment significantly increased the reaction rate. Eventually, the use of a Rushton Turbine at 20 rps with a shower disc sparger and a treated catalyst allowed the selectivity to reach 93%. The reaction could be described with a Power Law model satisfactorily. Transition Metal Oxide catalysts such as \(AgO/ SiO_2, Fe_2O_3/SiO_2, CuO/SiO_2\) and \(CuO/Al_2O_3\) were investigated as an alternative to the expensive noble metal based catalyst. However, it was shown that such catalysts are ineffective for the oxidation of different alcohols by studying the effects of different engineering parameters. The maximum conversion reached was 15% with calcined copper oxide catalyst for 1-octanol oxidation.
29
Surry, David Stuart. "The oxidation of organocuprates." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613779.
Full text
30
Lin, Hongqiao. "Lysine oxidation by myeloperoxidase." Cleveland State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=csu1449833806.
Full text
31
Audi, Ahmad Ali. "Surface studies of oxidation /." Search for this dissertation online, 2003. http://wwwlib.umi.com/cr/ksu/main.
Full text
32
MUSTIELES, MARÍN Irene. "Oxidation of phosphasalen complexes." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLX078/document.
Full textAbstract:
Les ligands phosphasalen développés au sein du laboratoire peuvent être considérés comme les analogues phosphorés des ligands salen dont ils diffèrent par la présence de groupements iminophosphorane à la place des imines. L’introduction de ces fonctions a d’importantes conséquences sur les propriétés de ces ligands, qui sont plus électrodonneurs et plus flexibles que les dérivés salen correspondants, capables de stabiliser des métaux à haut degré d’oxydation. Ces ligands ont également un caractère redox non-innocent, une propriété très étudiée de nos jours tant en chimie de coordination qu’en catalyse.Dans la cadre de cette thèse, différents ligands ont été synthétisés en modifiant les différents paramètres au sein du ligand : les substituants du cycle phenolate, MeO vs. tBu (PsalentBu et PsalenOMe); les substituants du phosphore, alkyl vs. aryl (iPrPsalen); et le lien entre les deux azotes, avec l’introduction de différentes o-phenylenediamines à la place d’ethylenediamine, qui donne les ligands Psalophen, PsalophenOMe2, PsalophenMe and PsalophenCF3.Les complexes neutres de cuivre et nickel, ainsi que les produits de mono-oxydation ont été synthétisés et caractérisés. Pour déterminer précisément la structure électronique des complexes différentes techniques ont été utilisés : des spectroscopies UV-visible, RMN et RPE, voltampérométrie cyclique, diffraction de rayons X, mesures magnétiques à l’état solide (SQUID), ainsi que des calculs DFT.De manière générale ces travaux montrent que les phosphasalen sont mieux à même de stabiliser la densité de spin sur le métal, donnant en certains cas des complexes à haute valence (NiIII, CuIII) encore rares dans la littérature. Dans certains cas les observations expérimentales et les calculs pointent vers un état fondamental multiconfigurationel. Contrairement aux ligands salen, les complexes portant un lien aromatique entre les deux azotes dimerisent lors de l’oxydation. Afin de contrôler la densité électronique sur ce cycle, une série des complexes à ligands phosphasalophen ont été également étudies.Une synthèse de complexes phosphasalen de manganèse(II) et (III) a été également réalisée. La stabilisation des complexes oxo ou nitrido, ainsi que la catalyse d’oxydation ont été envisagés avec ces complexes et des résultats prometteurs ont été obtenusPhosphasalen ligands developed in our laboratory can be considered as the phosphorous analogues of salen ligands where the imines have been substituted by iminophosphorane functions. The presence of the P-N bond makes these ligands more electro-donating and more flexible than salen analogues. They are able to stabilize high-valent metal complexes, as in the case of a Ni phosphasalen complex, which was characterized as a NiIII complex in solution and in solid state. This was never obtained before with salen-type ligands.Phosphasalen ligands, as the salen ones, can act as redox non-innocent ligands. Therefore, upon oxidation either the ligand or the metal center can be oxidized depending on the relative energy of metal and ligand orbitals. This behavior has been deeply investigated in coordination chemistry and in catalysis.In order to elucidate the factors that influence the oxidation locus different ligands have been synthetized modifiying the phenolate subtituents, MeO vs. tBu (PsalentBu and PsalenOMe); the phosphorous substituents, alkyl vs. aryl (iPrPsalen); and the linker between the two nitrogen atoms, ethylenediamine vs. phenylenediamine (Psalophen, PsalophenOMe2, PsalophenMe and PsalophenCF3).The neutral and one-electron oxidized copper and nickel complexes were synthetized and characterized. In order to determine the electronic structure of the complexes a combination of different characterization techniques were used: UV-vis, EPR and NMR spectroscopies, cyclic voltammetry, X-ray diffraction, magnetic measurements (SQUID), as well as theoretical calculations.In a general manner, phosphasalen ligands favor a metal center oxidation in a higher extent than salen derivatives, leading in some cases to high-valent metal complexes (NiIII, CuIII), remaining rare cases in the literature. For some complexes, experimental observations and theoretical calculations point to the presence of multiconfigurational ground states. Contrary to salen, complexes bearing an aromatic linker between the two nitrogen atoms dimerize upon oxidation. In order to tune the electronic density in the central ring, a series of phosphasalophen complexes displaying different substituents in the aromatic bridge, have been studied.Manganese (II) and (III) phosphasalen complexes has been also studied. The stabilization of oxo and nitride complexes as well as catalytic applications have been targeted for these complexes and encouraging results have been obtained
33
Malibo, Petrus Molaoa. "Development of heterostructured tin oxide nanocatalysts for the synthesis of bio-based maleic acid." University of Western Cape, 2021. http://hdl.handle.net/11394/8438.
Full textAbstract:
Philosophiae Doctor - PhDMaleic acid (MA) is a key intermediate for the synthesis of polyester resins, surface coatings, lubricant additives, plasticizers, copolymers, pharmaceuticals and agricultural chemicals. The current industrial production of MA is an energy-intensive gas-phase oxidation process of n-butane. The dwindling fossil resources and environmental issues have brought about a worldwide paradigm shift from fossil feedstocks to biomass resources for the sustainable production of fuel and chemicals. Furfural (FFR) and 5-hydroxymethylfurfural (HMF) are excellent biomass-derived platform chemicals, which present an alternative route for the production of renewable bio-based MA. There has been considerable success achieved in the oxidation of furfural and HMF to maleic acid and maleic anhydride with different catalysts in recent years.
34
Akinola, Adeniyi O. "Baeyer-Villiger Oxidation of 1,7- & 1,9-dibromopentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-dione." Thesis, University of North Texas, 2004. https://digital.library.unt.edu/ark:/67531/metadc4471/.
Full textAbstract:
Baeyer-Villiger oxidation of 1,9-dibromopentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-dione (1,9-dibromo-PCU-8,11-dione) was performed by using an excess amount of m-chloroperbenzoic acid (3 equivalents) and resulted in the formation of the corresponding monolactone. The reaction would not proceed to the dilactone stage. The structure of the reaction product was established unequivocally via single crystal X-ray diffraction. Baeyer-Villiger oxidation of 1,9-dibromo-PCU-8,11-dione using ceric ammonium nitrate (CAN) was also performed and afforded a mixture of lactones. Only one of these lactones, which also contained an alkene functionality, could be isolated and characterized. 1,7-dibromo-PCU-8,11-dione was also reacted with CAN, yielding the mono-lactone, which has also been characterized.
35
Wölk, Hans-Jörg. "Katalytisch-induzierte Änderungen der Morphologie von Kupferkatalysatoren." [S.l.] : [s.n.], 2002. http://edocs.tu-berlin.de/diss/2002/woelk_hans.pdf.
Full text
36
Shiju, N. R. "Support vanadium oxide catalysts in oxidation and oxidative dehydrogenation reaction: structure and catalytic properties." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2004. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2896.
Full text
37
Potts, Hayley Lynn. "Oxidation barrier and light protective packaging properties for controlling light induced oxidation in milk." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/80441.
Full textAbstract:
Fluorescent light exposure has well documented negative effects on fluid milk through oxidation reactions. A shift to light-emitting diode (LED) lights in retail dairy cases has occurred due to increased energy efficiency, but the effects of LED light on fluid milk are not known. The objective was to study the interaction of light protective additives (LPA) with a high oxygen barrier package under fluorescent and LED lighting conditions simulating a retail refrigerated dairy case. The extent of oxidation in 2% milk packaged in polyethylene terephthalate (PET) packages with different light interference properties (UV barrier, 2.1% titanium dioxide (TiO2) LPA, 4.0% TiO2 LPA, 6.6% TiO2 LPA) under light exposure up to 72h was compared to control packages (light-exposed, light-protected). Chemical measures of oxidation included dissolved oxygen content, formation of secondary lipid oxidation products, riboflavin degradation, and volatile analysis by electronic nose. Changes in dissolved oxygen content were associated closely with oxidation changes in milk over 72h. PET with 6.6% TiO2 was the most successful package, based on triangle test methodology, protecting milk sensory quality similar to light-protected milk through 8h LED light exposure. Based on a 9-point hedonic scale, (1=dislike extremely, 9=like extremely), consumers liked milk stored under LED light more (α=0.05; 6.59 ± 1.60) than milk stored under fluorescent light (5.87 ± 1.93). LED light is less detrimental to milk quality than fluorescent light and PET with high levels of TiO2 can protect milk quality for short periods of time under typical retail storage conditions.Master of Science in Life Sciences
38
Thanasawasdi, Haruthai Tungudomwongsa. "Photocatalytic oxidation of emerging contaminants : kinetics and pathways for photocatalytic oxidation of pharmaceutical compounds /." May be available electronically:, 2007. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
Full text
39
Woods, Matthew P. "Activity and Selectivity in Oxidation Catalysis." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1228175906.
Full text
40
Chang, Hui. "Oxidative stress in the retina an experimental study in the rat /." Lund : Dept. of Ophthalmology, University Hospital, Lund University, 1994. http://catalog.hathitrust.org/api/volumes/oclc/39725792.html.
Full text
41
Recchi, Carlo. "Selective photo-oxidation of glucose." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amslaurea.unibo.it/7650/.
Full textAbstract:
Biomass transformation into high-value chemicals has attracted attention according to the “green chemistry” principles. Low price and high availability make biomass one of the most interesting renewable resources as it provides the means to create sustainable alternatives to the oil-derived building blocks of the chemical industry In recent year, the need for alternative environmentally friendly routes to drive chemical reactions has in photocatalytic processes an interesting way to obtain valuable chemicals from various sources using the solar light as energy source. The purpose of this work was to use supported noble metal nanoparticles in the selective photo-oxidation of glucose through using visible light. Glucose was chosen as model molecule because it is the cheapest and the most common monosaccharide. Few studies about glucose photo oxidation have been conducted so far, and reaction mechanism is still not totally explained.
The aim of this work was to systematically analyze and assess the impact of several parameters (eg. catalyst/substrate ratio, reaction time, effect of the solvent and light source) on the reaction pathway and to monitor the product distribution in order to draw a general reaction scheme for the photo oxidation of glucose under visible light.
This study regards the reaction mechanism and the influence of several parameters, such as solvent, light power and substrate concentration. Furthermore, the work focuses on the influence of gold and silver nanoparticles and on the influence of metal loading. The glucose oxidation was monitored through the mass balance and the products selectivity. Reactions were evaluated in terms of glucose conversion, mass balance and selectivities towards arabinose and gluconic acid.
In conclusion, this study is able to demonstrate that the photo oxidation of glucose under visible light is feasible; the full identification of the main products allows, for the first time, a comprehensive reaction mechanism scheme.
42
Feussner, Ivo. "Oxidation von Polyenfettsäuren durch Lipoxygenasen." [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=961705108.
Full text
43
Malumbazo, Nandi. "Immobilized catalysts for alkene oxidation." Thesis, University of the Western Cape, 2007. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_1206_1257925149.
Full textAbstract:
Tertiary butyl substituted and unsubstituted Schiff base systems containing N,O donor ligands (Salicylaldimines) with aminotriethoxysilane tail were synthesized and complexed to Copper and Cobalt acetate. In this study, the effect of metal, reaction time, nature of oxidant (hydrogen peroxide tertiary butyl hydroperoxide), substituents on thel igand and substrate concentration, were investigated.
44
Osborn, Anna. "Measurements of Human Plasma Oxidation." Thesis, University of Canterbury. Biological Sciences, 2006. http://hdl.handle.net/10092/1426.
Full textAbstract:
The oxidation of lipids and antioxidants has been extensively studied in human plasma but little attention has been given to how plasma proteins are oxidised. Proteins make up the majority of biomolecules in cells and plasma and therefore are the most likely reactants with oxidants and free radicals. Previous studies in the laboratory had shown that peroxyl radicals generated by the thermolytic decay of 2-azobis (2-amdinopropane) dihydrochloride (AAPH) generated significant amounts of protein hydroperoxides, but only after a six hour lag period. In this study the existence of the six hour lag period was confirmed and shown by dialysis of the plasma to be due to the presence of low molecular weight antioxidants. The addition of both uric acid and ascorbic acid to the dialysed plasma restored the lag phase suggesting that in vivo these antioxidants act to prevent protein hydroperoxide formation. Lipid oxidation was also observed in the plasma but only after a two hour lag phase. This was the first time lipid oxidation has been observed in the absence of protein oxidation. The lipid lag phase was also abolished by dialysis of the plasma and restored by the addition of ascorbic acid and uric acid. The kinetics of tocopherol loss suggests that the tocopherol radicals act to inhibit lipid oxidation by transferring the electrons to the water-soluble ascorbate. The loss of ascorbate appears to cause the formation of a tocopherol radical mediate the lipid peroxidation process. Overall the data shows ascorbic acid scavenging the peroxyl radicals while uric acid acts to reduce the overall AAPH generated radical flux. In a separate investigation, the production of protein-bound DOPA (PB-DOPA) on albumin during X-ray radiolysis and copper mediate Fenton oxidation was investigated using a fluorescence based derivatisation method (ED-DOPA), which was compared with the more specific acid hydrolysis and HPLC analysis method. The ED-DOPA method consistently gave a much higher reading that the HPLC based methods, suggesting that the ED-DOPA method was measuring DOPA plus DOPA oxidation products. This was confirmed by oxidising X-ray radiolysis generated PB-DOPA with Cu++ to cause DOPA oxidation. The Cu++ treatment drastically increased the level of signal given by the ED-DOPA assay while HPLC analysis showed all the DOPA had been oxidised.
45
Keech, Peter George. "Electrochemical oxidation of simple indoles." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ61917.pdf.
Full text
46
Hasan, Saleem. "Porphyrin-catalyzed oxidation of trichlorophenol /." Access abstract and link to full text, 1994. http://0-wwwlib.umi.com.library.utulsa.edu/dissertations/fullcit/9500706.
Full text
47
Abussaud, Basim Ahmed. "Wet air oxidation of benzene." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103362.
Full textAbstract:
Processing of petrochemical compounds produces a large amount of wastewater. This wastewater consists of toxic (hazardous) materials that can not be discharged to the environment without treatment. As restrictive environmental constraints increase, new technologies are needed to treat those toxic materials before discharging them to the environment. Wet Air Oxidation (WAO) is one of these new methods.This study casts light on the effect of initial pH on the WAO of benzene at different temperatures and pressures. It was found that at pH 6, a temperature of 260°C and a partial pressure of oxygen of 1.38 MPa around 97% degradation was achieved in one hour. When the initial pH was lowered to 4 more than 90% degradation was achieved at 220°C and PO2 of 1.38 MPa in only 15 minutes.` It was concluded that the higher the temperature the better the benzene degradation, and the faster benzene degradation has been obtained with the increasing partial pressure of oxygen. The main intermediates were acetic acid and formic acid.
Furthermore, it was found that the degradation of benzene can be further enhanced in the presence of phenol. The main reason can be attributed to the effect of the free radicals generated from the fast phenol degradation. A simplified pathway for oxidation of benzene was proposed.
48
Müller, Birgit [Verfasser]. "Oxidation von Diorganodichalkogeniden / Birgit Müller." Berlin : Freie Universität Berlin, 2010. http://d-nb.info/1028494351/34.
Full text
49
Papangelakis, V. G. (Vladimiros George) 1958. "Aqueous pressure oxidation of arsenopyrite." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65435.
Full text
50
Kumarasamy, Puvaneswary. "Heterogeneous catalysis for methane oxidation." Thesis, Brunel University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326890.
Full text