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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.
31

An experimental study of the measurement of low concentration hydrogen sulfide in an aqueous solution

Wu, Dongqing 29 September 2006 (has links)
Endogenously generated H2S has been found not just a toxic substance but may play positive roles, such as the neuromodulator and vasorelaxant in the physiological system since 1990s. Then the precise control of the amount of Hydrogen Sulfide in the animal body raises great interests recently. However, the traditional methods for the Hydrogen Sulfide measurement need a large amount of tissue samples and take a complex procedure; it is impossible to develop any in-vivo real-time approach to measure H2S along the avenue of these methods. There is a great significance to develop new methods toward the measurement of Hydrogen Sulfide in in-vivo, real time, non- or less invasive manner with high resolution. One general idea to make the measurement less invasive is to take blood as sample i.e., to measure Hydrogen Sulfide in blood. <p>The study presented in this thesis aimed to conceive of new measurement methods for Hydrogen Sulfide in an aqueous solution along with their experimental verification. Though the blood sample will eventually be taken, the present study focused on an aqueous solution, which is a first step towards the final goal to measure Hydrogen Sulfide in blood. The study conducted a thorough literature review, resulting in the proposal of five methods, including: (i) the Hydrogen Sulfide measurement by Atomic Force Microscopy, (ii) the H2S measurement by Raman spectroscopy directly, (iii) the Hydrogen Sulfide measurement by Gas Chromatography/Mass Spectroscopy directly (with the static headspace technique), (iv) the Hydrogen Sulfide measurement by Mass Spectroscopy with Carbon Nanotubes, and (v) the Hydrogen Sulfide measurement by Raman spectroscopy with Carbon Nanotubes. The experiments for each of these methods were carried out, and the results were analyzed. Consequently, this study shows that method (v) is very promising to measure low concentration Hydrogen Sulfide in an aqueous solution, especially with the concentration level down to 10 μM and the presence of a linear relationship between the Hydrogen Sulfide concentration and its luminescent intensity.
32

Measurement of low concentration and nano quantity hydrogen sulfide by carbon nanotube

Wu, Xiao Chu 17 December 2007 (has links)
Traditionally, hydrogen sulfide (H2S) has been regarded as toxic. It can affect the various human systems and even cause death. However, research in the 1990s has shown that H2S can be endogenously generated by many cells and tissues in mammalian bodies, and that H2S also may play physiological roles such as those of neuromodulator and vasorelaxant in the biological system. As such, the precise measurement of the amount of H2S in a mammalian body has generated researchers strong interest. The ultimate goal of such a measurement should be conducted in-vivo and in real time.<p>The existing methods for H2S measurement require both a large quantity of tissue samples and a complex procedure, so they are not highly practicable for the purpose of achieving the aforementioned goal. In this dissertation, a new method that uses carbon nanotube as an absorbent or transducer and laser-based microscopy techniques (Raman and confocal laser scanning microscopy) as signal excitation and acquisition is proposed and developed. Experimental studies are described of using this new method for analysis of both distilled water samples and serum samples in which a group of proteins are present. <p>The study concludes that the new method (1) can measure H2S in water solutions down to a low level of concentration of 10 µM, (2) can measure H2S in sera down to a low concentration of approximately 20 µM), and (3) has a high feasibility for being used in the clinical context. Regarding (3), this is confirmed by presenting a control system that allows the laser microscopy to track carbon nanotube in a solution that has Brownian motion.<p>While not having reached the ultimate goal as mentioned above, this work advances the state-of-the-art of the measurement of low concentration and nano-quantity of H2S in water and serum samples, in particular providing a promise toward a real-time and in-vivo H2S measurement.
33

Fundamental study of measurement of low concentration hydrogen sulfide in sera using carbon nanotube

Zhan, Junji (Eric) 25 January 2011 (has links)
The study presented in this thesis was aimed to gain the fundamental knowledge regarding the mechanism of H2S measurement in sera by using carbon nanotubes (CNT) and fluorescence response. Characterization techniques such as Raman spectroscopy, X-ray absorption spectroscopy (XAS) and confocal laser scanning microscopy (CLSM) were employed to achieve this goal. The model system used for this study was composed of H2S, distilled water, two major serum proteins (albumin and globulin), serum, hemoglobin, and CNT. The results of this study showed that: (1) Two major serum proteins (albumin and globulin) are physically adsorbed on the sidewall of the CNTs; while H2S is adsorbed on the defect site of the CNTs. (2) Presence of the proteins on the CNTs did not affect the CNTs adsorption of H2S. (3) Using CLSM with the incident wavelength of 514 nm and the emission wavelength of 530 to 580 nm to acquire the fluorescence response of the H2S adsorbed on the CNTs is a reliable approach to measure H2S in sera. (4) Single-wall carbon nanotubes (SWNTs) outperform multi-wall carbon nanotubes (MWNTs) in measurement sensitivity. (5) Presence of hemoglobin in a H2S solution did not affect the measurement of H2S with CNTs and CLMS. The study described in this thesis has provided new knowledge of the interaction behaviors of CNTs with H2S and major proteins in sera along with the mechanism which governs these behaviors. Such knowledge is very useful to further advance the CNT approach to sensing H2S in sera and water solution and to further extend the approach to sensing H2S in other mammalian tissues such as blood.
34

Biogas desulfurization: Performane study of a full-scale scrubber for biogas desulfurization

Hung, Kuo-Teng 13 July 2001 (has links)
In this study, a set of full-scale two-stage-in-series scrubbing tower was constructed to test its performance for desulfurization of biogas from three anaerobic UASB (upflow anaerobic sludge blanket) reactors of a wastewater plant for treating corn-syrup processing wastewater. Each stage of the absorbing towers was constructed from a 0.6m ¡Ñ 6 m (I.D. ¡Ñ H) plastic column packed with plastic packings (4¡¨ K6 Heilex-Type or 2.5¡¨ Crown-Biopacks with packing heights of 5 m and 3.65 m, respectively). Effluent from the activated sludge sedimentation tank of the wastewater plant was used as a scrubbing liquid and the tower effluent liquid was discharged into the activated sludge tank for oxidation of the absorbed hydrogen sulfide. Results of a continuous operation period of 20 weeks indicate that H2S of 380-19,000 ppm in the biogas could be reduced to 1-2,100 ppm by the scrubbing towers with superficial liquid and gas velocities of GL = 13.2-28.1 and GV = 306-642 m/h, respectively. On an average, the effluent gas contained a H2S concentration of less than 300 ppm and the removal efficacy was more than 96%. Results also indicate that as pH of the scrubbing liquid increased from 7.7 to 8.8, the overall H2S removal efficacy raised from 86 to 98%. About 1/3 of the absorbed H2S-S was detected as H2S-S and SO4-2-S in the tower effluent. The rest was supposed to be as elemental sulfur in a slimy form which sticked to the packing surface. This might be the reason for the increasing pressure drop with the operation time. A set of performance and gas-liquid equilibrium equations were proposed to estimated the influence of liquid pH, gas and liquid flow rates, and packing height on the H2S removal efficacy. Calculation results indicate, at 30oC, the minimum liquid/gas ratios (L/G)min for the absorption are 0.043 and 0.014 m3/m3, respectively, for fresh absorbing liquids with pH = 8.0 and 8.5. Based on the proposed equations and the experimental data, the volumetric mass-transfer coefficient Kya for H2S absorption in the towers could be expressed approximately as Kya =1.15¡Ñ1017GV1.0GL-3.0 with GV =304-644 and GL = 15.1-28.1 m3/m2.h, and liquid pH 7.7-8.6. It was supposed that too much liquid loading leads to a decrease in the specific area a for mass transfer which results in the Kya decrease.
35

Oxidation in electric discharges.

Wiseman, Nicholas. January 1971 (has links)
No description available.
36

Characterization of copper supported on titanosilicates for room temperature H2S adsorption

Tavana, Aida Unknown Date
No description available.
37

Modeling Hydrogen Sulfide Adsorption by Activated Carbon made from Anaerobic Digestion By-product

Ho, Natalie 25 July 2012 (has links)
Biogas, produced from anaerobic digestion of cattle manure, is an attractive alternative energy source as it is rich in methane. However, it is necessary to remove hydrogen sulfide from the biogas before it can be used in engines for electricity generation. Currently, large scale biogas systems employ physical adsorbing solvents to upgrade and purify biogas which is not economically feasible for small scale biogas systems. Activated carbon made from anaerobic digestate proves to be an effective adsorbent of hydrogen sulfide because it has minimal operating costs and essentially zero raw material cost. A model is developed to predict the adsorption capacity, carbon bed life span, and breakthrough time for this carbon material. By analyzing the reaction constant, adsorption constant, and degradation constant, adsorption behavior under different operating conditions were studied. The model can be scaled-up to model adsorption for biogas loading rates for small to large scale cattle farms.
38

Modeling Hydrogen Sulfide Adsorption by Activated Carbon made from Anaerobic Digestion By-product

Ho, Natalie 25 July 2012 (has links)
Biogas, produced from anaerobic digestion of cattle manure, is an attractive alternative energy source as it is rich in methane. However, it is necessary to remove hydrogen sulfide from the biogas before it can be used in engines for electricity generation. Currently, large scale biogas systems employ physical adsorbing solvents to upgrade and purify biogas which is not economically feasible for small scale biogas systems. Activated carbon made from anaerobic digestate proves to be an effective adsorbent of hydrogen sulfide because it has minimal operating costs and essentially zero raw material cost. A model is developed to predict the adsorption capacity, carbon bed life span, and breakthrough time for this carbon material. By analyzing the reaction constant, adsorption constant, and degradation constant, adsorption behavior under different operating conditions were studied. The model can be scaled-up to model adsorption for biogas loading rates for small to large scale cattle farms.
39

Microbial desulfurization of natural gas /

Sublette, Kerry Lyn. January 1985 (has links)
Thesis (Ph.D.)--University of Tulsa, 1985. / Bibliography: leaves 186-192.
40

CO₂ top of the line corrosion in the presence of H₂S

Manuitt, Alvaro Camacho January 2006 (has links)
Thesis (M.S.)--Ohio University, August, 2006. / Title from PDF t.p. Includes bibliographical references.

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