Browsing by Subject "oxidation"

Now showing 1 - 20 of 24

A Survey: Destruction of Chemical Agent Simulants in Supercritical Water Oxidadtion
(University of Texas at Austin, 1992-10) Blank, M.R.; Gloyna, E.F.
Behavior of Chromium During Sueprcritical Water Oxidation
(University of Texas at Austin, 1993-07) Rollans, S.; Gloyna, E.F.
Corrosion Behavior of High-Grade Alloys in the Supercritical Water Oxidation of Sludges
(University of Texas at Austin, 1991-02) Thomas, A.J. III; Gloyna, E.F.
Corrosion Behavior of Three High-Grade Alloys in Supercritical Water Oxidation Environments
(University of Texas at Austin, 1992-06) Matthews, C.F.; Gloyna, E.F.
Cyclone Performance for the Separation of Solids from Supercritical Water Oxidation Effluents
(University of Texas at Austin, 1995-01) Laspidou, C.S.; Gloyna, E.F.
Degradation Of Trichloroethylene By Methanol-Grown Cultures Of Methylosinus Trichosporium Ob3B Pp358
(1996-03) Fitch, Mark W.; Speitel, Gerald E.; Georgiou, George; Fitch, Mark W.; Speitel, Gerald E.; Georgiou, George
A soluble methane monooxygenase-constitutive mutant strain of Methylosinus trichosporium OB3b, strain PP358, was grown with methanol as the carbon source, and the kinetics of trichloroethylene (TCE) degradation were determined. PP358 exhibited high TCE degradation rates under both oxygen- and carbon-limiting conditions. The optimal pseudo first-order rate constant for TCE was comparable to the values measured for cells grown,vith methane. We found that growth under oxygen-limiting conditions results in increased accumulation of polyhydroxybutyrate, which in turn correlates,vith higher transformation capacities for TCE. It was also shown that methanol inhibits TCE degradation only at high concentrations. Thus, methanol-grown cultures of PP358 represent an efficient system for the biodegradation of chlorinated hydrocarbons.
Destruction of Toxic Organic Materials by Supercritical Water Oxidation
(University of Texas at Austin, 1994-08) Griffith, J.W.; Gloyna, E.F.
Elemental Ratio Measurements of Organic Compounds Using Aerosol Mass Spectrometry: Characterization, Improved Calibration, and Implications
(2015) Canagaratna, M. R.; Jimenez, J. L.; Kroll, J. H.; Chen, Q.; Kessler, S. H.; Massoli, P.; Ruiz, L. Hildebrandt; Fortner, E.; Williams, L. R.; Wilson, K. R.; Surratt, J. D.; Donahue, N. M.; Jayne, J. T.; Worsnop, D. R.; Ruiz, L. Hildebrandt
Elemental compositions of organic aerosol (OA) particles provide useful constraints on OA sources, chemical evolution, and effects. The Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) is widely used to measure OA elemental composition. This study evaluates AMS measurements of atomic oxygen-to-carbon (O : C), hydrogen-to-carbon (H : C), and organic mass-to-organic carbon (OM : OC) ratios, and of carbon oxidation state ((OS) over bar (C))for a vastly expanded laboratory data set of multifunctional oxidized OA standards. For the expanded standard data set, the method introduced by Aiken et al. (2008), which uses experimentally measured ion intensities at all ions to determine elemental ratios (referred to here as "Aiken-Explicit"), reproduces known O: C and H: C ratio values within 20% (average absolute value of relative errors) and 12%, respectively. The more commonly used method, which uses empirically estimated H2O+ and CO+ ion intensities to avoid gas phase air interferences at these ions (referred to here as "Aiken-Ambient"), reproduces O: C and H: C of multifunctional oxidized species within 28 and 14% of known values. The values from the latter method are systematically biased low, however, with larger biases observed for alcohols and simple diacids. A detailed examination of the H2O+, CO+, and CO2+ fragments in the high-resolution mass spectra of the standard compounds indicates that the Aiken-Ambient method underestimates the CO C and especially H2O+ produced from many oxidized species. Combined AMS-vacuum ultraviolet (VUV) ionization measurements indicate that these ions are produced by dehydration and decarboxylation on the AMS vaporizer (usually operated at 600 degrees C). Thermal decomposition is observed to be efficient at vaporizer temperatures down to 200 degrees C. These results are used together to develop an "Improved-Ambient" elemental analysis method for AMS spectra measured in air. The Improved-Ambient method uses specific ion fragments as markers to correct for molecular functionality-dependent systematic biases and reproduces known O : C (H : C) ratios of individual oxidized standards within 28% (13 %) of the known molecular values. The error in Improved-Ambient O : C (H : C) values is smaller for theoretical standard mixtures of the oxidized organic standards, which are more representative of the complex mix of species present in ambient OA. For ambient OA, the Improved-Ambient method produces O : C (H : C) values that are 27% (11 %) larger than previously published Aiken-Ambient values; a corresponding increase of 9% is observed for OM : OC values. These results imply that ambient OA has a higher relative oxygen content than previously estimated. The (OS) over bar (C) values calculated for ambient OA by the two methods agree well, however (average relative difference of 0.06 (OS) over bar (C) units). This indicates that (OS) over bar (C) is a more robust metric of oxidation than O : C, likely since (OS) over bar (C) is not affected by hydration or dehydration, either in the atmosphere or during analysis.
Energy Consumption in the Destruction of Wastewaters and Sludges by Supercritical Water Oxidation Deep-Shaft Reactors
(University of Texas at Austin, 1991-03) Stanford, C.C.; Gloyna, E.F.
Formation and Aging of Secondary Organic Aerosol from Toluene: Changes in Chemical Composition, Volatility, and Hygroscopicity
(2015) Ruiz, L. Hildebrandt; Paciga, A. L.; Cerully, K. M.; Nenes, A.; Donahue, N. M.; Pandis, S. N.; Ruiz, L. Hildebrandt
Secondary organic aerosol (SOA) is transformed after its initial formation, but this chemical aging of SOA is poorly understood. Experiments were conducted in the Carnegie Mellon environmental chamber to form secondary organic aerosol (SOA) from the photo-oxidation of toluene and other small aromatic volatile organic compounds (VOCs) in the presence of NOx under different oxidizing conditions. The effects of the oxidizing condition on organic aerosol (OA) composition, mass yield, volatility, and hygroscopicity were explored. Higher exposure to the hydroxyl radical resulted in different OA composition, average carbon oxidation state (OSc), and mass yield. The OA oxidation state generally increased during photo-oxidation, and the final OA OSc ranged from -0.29 to 0.16 in the performed experiments. The volatility of OA formed in these different experiments varied by as much as a factor of 30, demonstrating that the OA formed under different oxidizing conditions can have a significantly different saturation concentration. There was no clear correlation between hygroscopicity and oxidation state for this relatively hygroscopic SOA.
Heat Transfer to Watch in Countercurrent Flow Within a Vertical, Concentric-Tube Supercritical Water Oxidation Reactor
(University of Texas at Austin, 1990-07) Michna, R.J.; Gloyna, E.F.
Methylosinus-Trichosporium Ob3B Mutants Having Constitutive Expression Of Soluble Methane Monooxygenase In The Presence Of High-Levels Of Copper
(1992-11) Phelps, Patricia A.; Agarwal, Sandeep K.; Speitel, Gerald E.; Georgiou, George; Phelps, Patricia A.; Agarwal, Sandeep K.; Speitel, Gerald E.; Georgiou, George
The methanotrophic bacterium Methylosinus trichosporium OB3b is unusually active in degrading recalcitrant haloalkanes such as trichloroethylene (TCE). The first and rate-limiting step in the degradation of TCE is catalyzed by a soluble methane monooxygenase (sMMO). This enzyme is not expressed when the cells are grown in the presence of copper at concentrations typically found in polluted groundwater. Under these conditions, M. trichosporium OB3b expresses a particulate form of the enzyme (pMMO), which has a narrow substrate specificity and does not degrade TCE at any significant rate. We have isolated M. trichosporium OB3b mutants that are deficient in pMMO and express sMMO constitutively in the presence of elevated concentrations of copper. One mutant (PP358) exhibited a TCE degradation rate which was almost twice as high as that of the wild-type strain grown under optimal conditions (without copper). All of the mutants lost the ability to express pMMO activity and to form stacked intracellular membranes characteristic of wild-type cells expressing pMMO.
Naphthalimide Trifluoroacetyl Acetonate: A Hydrazine-Selective Chemodosimetric Sensor
(2013-08) Lee, Min Hee; Yoon, Byungkwon; Kim, Jong Seung; Sessler, Jonathan L.; Lee, Min Hee; Sessler, Jonathan L.
The trifluoroacetyl acetonate naphthalimide derivative 1 has been synthesized in good yield. In acetonitrile solution, compound 1 reacts selectively with hydrazine (NH2NH2) to give a five-membered ring. This leads to OFF-ON fluorescence with a maximum intensity at 501 nm as well as easily discernible color changes. Based on a readily discernible and reproducible 3.9% change in overall fluorescence intensity, the limit of detection for 1 is 3.2 ppb (0.1 mu M), which is below the accepted limit for hydrazine set by the U.S. Environmental Protection Agency (EPA). Compound 1 is selective for hydrazine over other amines, including NH4OH, NH2OH, ethylenediamine, methylamine, n-butylamine, piperazine, dimethylamine, triethylamine, pyridine, and is not perturbed by environmentally abundant metal ions. When supported on glass-backed silica gel TLC plates, compound 1 acts as a fluorimetric and colorimetric probe for hydrazine vapor at a partial pressure of 9.0 mm Hg, with selectivity over other potentially interfering volatile analytes, including ammonia, methylamine, n-butylamine, formaldehyde, acetaldehyde, H2O2, HCl, and CO2 being observed. Probe 1 can also be used for the detection of hydrazine in HeLa cells and does so without appreciable interference from other biologically abundant amines and metal ions.
Subcritical and Supercritical Water Oxidation of Industrial, Excess Activated Sludge
(University of Texas at Austin, 1990-11) Shanableh, A.; Gloyna, E.F.
Supercritical Water Oxidation and Hydrolysis Kinetics of Pyridine and 2,4-Dichlorophenol
(University of Texas at Austin, 1993-10) Crain, N.E.; Gloyna, E.E.
Supercritical Water Oxidation Model Development for Selected EPA Priority Pollutants
(University of Texas at Austin, 1993-12) Gloyna, E.F.; Li, L.
Supercritical Water Oxidation of Acetamide and Acetic Acid
(University of Texas at Austin, 1990-09) Lee, D.S.; Gloyna, E.F.
Supercritical Water Oxidation of Acetic Acid Catalyzed by CeO2/MnO2
(University of Texas at Austin, 1992-09) Frisch, M.A.; Gloyna, E.F.
Supercritical Water Oxidation of Anaerobically Digested Municipal Sludge
(University of Texas at Austin, 1991-03) Tongdhamachart, C.; Gloyna, E.F.
Supercritical Water Oxidation of Dimethyl Methylphosphonate and Thiodiglycol
(University of Texas at Austin, 1994-12) Turner, M.D.; Gloyna, E.F.