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1
Fu, Man On. "Novel adsorbents for sulphur dioxide removal /". View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?EVNG%202009%20FU.
Testo completo
2
Thompson, Linda Helen. "Reactions in liquid sulphur dioxide based media". Thesis, University of Nottingham, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335469.
Testo completo
3
Buckenham, A. H. "Effects of sulphur dioxide on stomatal functioning". Thesis, University of Nottingham, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378436.
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4
Zaft, Paul E. "A microcomputer compensated sensor for sulphur dioxide". Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46626.
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5
Harman, Neil F. "Aspects of the lithium-sulphur dioxide cell". Thesis, Loughborough University, 1986. https://dspace.lboro.ac.uk/2134/33142.
Testo completoAbstract (sommario):
An open electrolytic cell has been designed and constructed for use in a dry environment. This was used to investigate the passivation processes concerned with both the lithium and the carbon (SO2) electrodes. A.c. impedance techniques have been used in both two and three terminal cell systems in order to study the kinetics of the electrode processes. Effects of temperature, state-of-charge and reverse cell operation have been studied. Computer simulations were made of the growth of crystals on a flat (Li) surface and the resulting growth transients connecting current and time were derived. This model was extended to simulate the porous carbon (SO2) electrode and the utilisation of the carbon as a function of the depth of reaction penetration into the electrode is devised for both potentiostatic and galvanostatic discharging.
6
Mulligan, David John. "Reduction of sulphur dioxide over transition metal sulphides". Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61916.
Testo completo
7
Harrison, K. A. "The fate of sulphur dioxide in meat products". Thesis, University of Leeds, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233204.
Testo completo
8
Famulari, Daniela. "Surface-atmosphere exchange of ammonia and sulphur dioxide". Thesis, University of Edinburgh, 2005. http://hdl.handle.net/1842/10883.
Testo completoAbstract (sommario):
Field measurements of the surface – atmosphere exchange of SO2 and NH3 have been made using two very different micrometeorological methods, a long term averaging method based on flux-gradient principles and an eddy covariance method, using a tunable diode laser fast response gas analysis system. The field data are then applied in surface-atmosphere models to calculate deposition of pollutant gases at the regional scale. The Time Averaged Gradient system (TAG) has been developed following a prototype implemented during a pilot study in 1998. The main goal of the TAG is to provide direct long-term average (1 to 4 weeks) flux-gradient measurements for a range of trace gas species, between atmosphere and terrestrial surfaces. Over daily periods, atmospheric conditions can range from high stability, where the vertical gradients of ambient concentration are enhanced due to very small diffusivity, to highly unstable conditions, in which concentration gradients are small due to the intense turbulent activity of the surface layer. By sampling continuously over a long-term period, the large vertical gradients generated by high stability would lead to an over-estimate of the actual flux; therefore it is necessary to avoid the bias due to these processes. To overcome this problem, the TAG system operates conditionally, sampling the micrometeorological variables within a carefully defined range of stability. A data series of five years, from 1999 to 2003, for SO2 and a data series of two years, from 2001 to 2003 for NH3 has been obtained at Auchencorth Moss, a field site in Southern Scotland. The measurements provided a characterisation of the chemical climate, meteorology, turbulent characteristics, as well as deposition-emission rates at the field site. A comparison with a continuous flux-gradient system running in parallel on the same field site allowed the reliability of the TAG system to be quantified: the correlation coefficients for u* and H show a very good agreement (above 90% in both cases) between TAG protocol and continuous system suggesting the removal of stable conditions from the sampling period doesn’t modify the evaluation of the turbulent fluxes, although it introduces a bias. The SO2 fluxes calculated omitting stable conditions under-estimate the fluxes of SO2 measured by the continuous system by providing fluxes that are the 77% of the values estimated with the continuous system. A second TAG system has been implemented to improve estimates of gradients and reduce uncertainty on the fluxes and to increase the data coverage. It has been tested on the Easter Bush field site (Southern Scotland) measuring NH3 fluxes form autumn 2001 to spring 2003. Field measurements of NH3 fluxes using an eddy covariance technique were made for a total of 60 days between July and October 2002 at intensively managed grassland in Southern Scotland. The collected data demonstrate the suitability of a Tuneable Diode Laser Absorption Spectroscopy (TDLAS) system coupled with a sonic anemometer for eddy covariance measurements.
9
Rao, Sumitrananda N. R. "Novel adsorbents using metal complexes". Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/10200.
Testo completo
10
Mulligan, David John. "Reduction of sulphur dioxide over supported molybdenum sulphide catalysts". Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39497.
Testo completoAbstract (sommario):
The reduction of sulphur dioxide with methane using various supported molybdenum catalysts has been studied. Catalysts were prepared using either alumina or a silica-alumina support. For the alumina supported catalysts, the molybdenum loadings of 5, 10 or 15% were used. These catalysts were sulphided using 12% H$ sb2$S in argon or a mixture of SO$ sb2$ and CH$ sb4$ in argon. The 15% $ rm Mo/Al sb2O sb3$ catalyst sulphided with H$ sb2$S was at least 1.5 times as active as the other alumina supported catalysts and had the highest yields of elemental sulphur and CO$ sb2$ and was 10 times as active as the silica-alumina supported catalyst with the same molybdenum loading. The addition of cobalt to the 15% $ rm Mo/Al sb2O sb3$ catalyst decreased the activity by 20%. Alumina supported molybdenum catalysts sulphided using a mixture of 25% SO$ sb2$, 25% CH$ sb4$ and 50% Ar were more active, and had higher yields of sulphur and CO$ sb2$ than alumina itself. However, these catalysts were not as active as catalysts with a similar molybdenum loading which were sulphided using H$ sb2$S because the H$ sb2$S sulphided catalysts had a higher MoS$ sb2$ content. Kinetic experiments were carried out using the H$ sb2$S sulphided 15% Mo/$ rm Al sb2O sb3$ catalyst. A rate expression was developed at the temperatures of 600, 625, and 650$ sp circ$C. The results indicate that the reaction is methane adsorption controlled.
11
Coetzee, Morné Pieter. "Upscaling of a sulphur dioxide depolarized electrolyzer / Coetzee, M.P". Thesis, North-West University, 2012. http://hdl.handle.net/10394/7001.
Testo completoAbstract (sommario):
In the last couple of years there has been a great need for finding alternative, cleaner burning fuel sources. This search has led to the development of various hydrogen technologies. The reason for this is that when burnt, hydrogen gas only forms water and oxygen as products. One of the methods used in the production of hydrogen gas is that of the electrolysis of sulphur dioxide which is facilitated by a sulphur dioxide depolarized electrolyzer. The electrolysis of sulphur dioxide has the advantage of requiring lower cell voltages in the electrolysis process when compared to the electrolysis of water.
This type of electrolyzer unfortunately suffers from low hydrogen gas production volumes. It was thought that by linearly increasing the reactions active area of the electrolyzer, the production volumes can be increased. A linearly upscaled 100cm2 cell was designed by using computer aided design software, such as SolidWorks, Cambridge Engineering Selector, EES and ANSYS. The cell was then constructed and tested to determine the effects of linearly upscaling. The results of the 100cm2 cell were compared to the results of a similar 25cm2 cell and results obtained from the literature. The 100cm2 cell exhibited very poor performance when compared to the other cells. The 100cm2 cell showed lower hydrogen production volumes at higher energy inputs than the 25cm2 cell and an 86cm2 stack assembly. It was concluded that creating stack assemblies with cells with smaller active areas would be much more efficient than linearly upscaling the active area of the cells.Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2012.
12
Graham, N. K. "Metal chemistry in non-aqueous solutions containing sulphur dioxide". Thesis, University of Leeds, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373849.
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13
Phillips, Samantha Justine. "The ability of bryophytes to withstand sulphur dioxide pollution". Thesis, University of Sheffield, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284357.
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14
Hong, Pui-Kwan Andrew Hoffmann Michael R. Hoffmann Michael R. "Catalytic oxidation of sulphur dioxide by heterogeneous cobalt-phthalocyanine /". Diss., Pasadena, Calif. : California Institute of Technology, 1988. http://resolver.caltech.edu/CaltechETD:etd-11082007-080528.
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15
Barrelet, Timothée. "Norway spruce as an environmental archive for sulphur dioxide /". [S.l.] : [s.n.], 2006. http://www.zb.unibe.ch/download/eldiss/05barrelet_t.pdf.
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16
Gould, R. P. "The effects of gaseous sulphur dioxide and nitrogen dioxide on carbon allocation in plants". Thesis, Lancaster University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377896.
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17
Renner, Christine Joan. "Interactive effects of sulphur dioxide, nitrogen dioxide and the winter environment on Lolium perenne". Thesis, University of Newcastle Upon Tyne, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254029.
Testo completo
18
Atkin, Ian. "Improvement of sulphur dioxide yield from the sulphuric acid thermal decomposition process by membrane separation". Thesis, University of Sheffield, 2010. http://etheses.whiterose.ac.uk/14532/.
Testo completoAbstract (sommario):
This work investigates the feasibility of applying high temperature oxygen separation to the sulphuric acid decomposition process, a step used in large scale hydrogen production processes currently under development. Porous and dense membranes are both considered. Equilibrium calculations show yttria-stabilised zirconia (YSZ), combined with platinum electrodes, to be a candidate membrane. Process simulations show the potential sulphur dioxide yield increases that could be achieved through the use of a high temperature oxygen separation membrane in two different configurations. Bespoke experimental apparatus was designed, procured and assembled in order to investigate the oxygen flux through YSZ membranes in the presence of sulphur dioxide, during external voltage application. Experiments were performed in the 700 - 900°C temperature range. Results show that oxygen permeation through YSZ membranes occurs under these conditions. A decrease in oxygen permeation with time was observed and attributed to sulphur dioxide adsorption on to the platinum electrodes. Future work would concentrate on using variable applied voltages to reduce this performance decrease.
19
Shaw, Andrew Charles. "The simultaneous solubilty of sulphur dioxide and oxygen in water for the hybrid sulphur thermochemical cycle". Thesis, University of Sheffield, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.489067.
Testo completoAbstract (sommario):
Anthropogenic greenhouse gas emissions and rising oil prices call for a sustainable transportable energy source. Hydrogen is a promising replacement for carbon based fuels in vehicles. The HyS cycle, proposed by the Westinghouse Corporation, is a route to hydrogen production on a scale large enough to satisfy the requirements of the transport industry. The process is a hybrid thermochemical cycle based on the decomposition of sulphuric acid.
20
Esplin, Gordon John. "Heterogeneous reaction kinetics of sulphur dioxide and airborne limestone particles". Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/28379.
Testo completoAbstract (sommario):
The literature on acid rain provides evidence that large (>5 μm) alkaline particles in the atmosphere, which derived from surface soil, play an important role in mitigating the effect of acid rain. Not only do they help to neutralize acidity but they also are a source of nutrients to the terrestrial and aquatic environments.
While ground-up limestone has been added to the forests and the lakes of regions deficient in alkalinity, this mode of application is prohibitively expensive. An economic alternative method of distribution would utilize the advective and turbulent diffusive processes within the troposhere in order to supply limestone particles of approximately 10 μm diameter to the terrestrial and the aquatic environments. However, while the particles are being transported through the atmosphere they will also interact to some degree with the atmospheric pollutants (SO₂, NOx, photochemical oxidants, etc.). While the two-phase chemical interaction of water droplets and gaseous pollutants has been extensively studied, little is known about the reaction between limestone particles and gaseous pollutants under ambient conditions.
As a first step in understanding these processes laboratory experiments were conducted in order to measure the rate of the heterogeneous reaction between limestone particles and sulphur dioxide (SO₂) gas in clean humid air. Calcitic limestone (200-270 mesh Tyler) from Texada Island, B.C., was reacted with 30-80 ppb SO₂ at room temperature (17-22°C) over a humidity range of 70-100%. Ancillary experiments were also conducted to determine the maximum dissolution rate of these limestone particles in an acidic, aqueous environment. The overall rate (r) for the SO₂ reaction with Texada Island limestone was determined to be approximately first-order with respect to the SO₂ concentration and to be strongly dependent upon the relative humidity:
[Formula Omitted]
Limited experiments with precipitated dolomite indicated that it reacts with SO₂ somewhat faster than does the calcitic limestone.
A study of the individual mass transfer and reaction processes indicated that the rate limiting step for the overall reaction was the aqueous phase oxidation of the bisulphite ion. Limestone dissolution (determined experimentally), and estimated gas and aqueous phase diffusive processes, were not rate limiting. In a clean humid atmosphere, free of photochemical oxidants, a limestone aerosol would react very slowly with SO₂ (SO₂ removal rate of about 3x10⁻³% per hour).
However, in a humid polluted atmosphere rich in photochemical oxidants, similar to that responsible for acid fog and acid rain, the aqueous phase oxidation of dissolved SO₂ is not expected to be rate limiting. Under such conditions bisulphite dissociation: [Formula Omitted]
Therefore in humid, polluted atmospheres limestone aerosol will act as a "sink." for SO₂ for soluble photochemical oxidants, and probably also for HNO₃ (nitric acid). Since the oxidants are considered to be phytotoxic while the other pollutants are responsible for creating acid rain we conclude that the deployment of a limestone aerosol may have a positive impact on the atmospheric environment, besides being beneficial to the aquatic and terrestrial environments. It is strongly recommended that further research be done in this area in order to better quantify the rate processes, and perhaps also to identify practical methods for increasing the atmospheric concentration of alkaline aerosol in those geographic regions which are deficient.Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate
21
Schmidt, Kurt A. G. "Solubility of sulphur dioxide in mixed polyethylene glycol dimethyl ethers". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/mq22670.pdf.
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22
Mello, Marcus. "Adsorption of sulphur dioxide from multicomponent mixtures on hydrophobic zeolites". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0032/NQ65466.pdf.
Testo completo
23
Agha, Saad Arslan. "The control of sulphur dioxide emission from coal-fired stokers". Thesis, University of Leeds, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293819.
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24
Namor, Omar G. "Sorbic acid interaction with sulphur dioxide in model food systems". Thesis, University of Surrey, 1987. http://epubs.surrey.ac.uk/847780/.
Testo completoAbstract (sommario):
Sorbic acid and sulphur dioxide are often used together, as preservatives,in many foods. Sorbic acid is known to undergo degradation in aqueous solutions, and this degradation appears to be accelerated in the presence of sulphur dioxide. The interaction between sorbic acid and sulphur dioxide is the subject of this thesis. The work is subdivided into five chapters, as follows: The first chapter deals with the chemistry of sorbic acid acid and sulphur dioxide. The second chapter describes a study of the degradation products of sorbic acid, in aqueous systems, in the presence of sulphur dioxide and a possible mechanism for the occurrence of these products is proposed. Chapter three deals with the preparation and degradation of 6-[[13]C] sorbic acid in order to find evidence for, or against, the mechanism proposed in chapter two. It also gives details of syntheses attempted in order to obtain 6-[[13]C] sorbic acid. The interaction of sorbic acid and sulphur dioxide in real food systems is the subject of the fourth chapter. The food systems studied were mayonnaise, tomato puree, orange juice and cottage cheese. The effect of packaging on the rate of degradation of sorbic acid was also investigated. The final chapter deals with a microbiological study of two homologues of sorbic acid, 2,4-heptadienoic acid, 2,4-octadienoic acid. The fungicidal activity of these two compounds, towards selected fungi, was analysed. 4-0xobut-2-enoic acid, a degradation product of sorbic acid in aqueous systems, was also analysed as a possible fungistat.
25
Huang, Longbin. "Interactions between sulphur dioxide and soil salinity in wheat plants". Thesis, Huang, Longbin (1993) Interactions between sulphur dioxide and soil salinity in wheat plants. PhD thesis, Murdoch University, 1993. https://researchrepository.murdoch.edu.au/id/eprint/51916/.
Testo completoAbstract (sommario):
Increasing sulphur dioxide (SO2) concentration in the atmosphere with expansions of electricity production and mineral processing in the world has led to numerous studies and understandings of adverse impacts of SO2 on growth and physiology of plants in Although there have been many studies on SO2 dose-response (physiology, growth, and (or) yield) relationships in plants, there is a lack of understanding of influences of environmental stress such as NaCl salinity, on plant responses to elevated SO2 concentrations in the air, which may occur in agricultural areas such as India, China and Australia with agricultural and natural ecosystems. low rainfall, or artificial irrigation and elevated SO2 levels in the air. Since stomatal conductance predominantly controls SO2 uptake and then its toxicity in leaf cells, salinity induced-stomatal closure could decrease the SO2 uptake and protect plants against SO2 toxicity. On the other hand, SO2 itself may induce changes in stomatal conductance, this may in turn, influence leaf transpiration, then salt (NaCl) uptake from the transpiration stream, and eventual salt toxicity in NaCl salinity-stressed plants, Therefore, simultaneous exposure to soil NaCl salinity and SO2 may modify each other's effects on the responses of physiology and growth in the plants. The studies in this thesis examined responses of growth and physiology in wheat plants exposed to SO2, NaCl salinity and their combination under near ambient conditions.
Wheat (Triticum aestivum cv. Wilgoyne (Ciano/Gallo)) plants were exposed to factorial treatments of SO2 and NaCl salinity in fumigation chambers with rain-exclusion tops under near-ambient conditions. In experiment 1, wheat plants were exposed to a factorial combination of three levels of salinity (with high Na/Ca ratio): control, 50 and 100 mM NaCl, and three levels of SO2: < 10 (ambient), 44 and 107 nl 1-1 for 4 hours per day for up to 110 days. In experiment 2, wheat plants were exposed to a factorial combination of two levels of salinity (with low Na/Ca ratio): control and 50 mM NaCl, and three levels of SO2: < 10 (ambient), 231, and 441 nl 1-1 for 4 hours per day for up to 51 days.
Low concentrations of SO2 (44 and 107 nl 1-1) stimulated vegetative growth in early growth phase, but had no effect later. Exposure to higher SO2 concentration (441 nl 1-1) significantly decreased plant growth. Low SO2 concentrations increased grain yield, but higher SO2 concentration (441 nl 1-1) decreased ear yield. Shoot to root ratios in plants were not changed by the low SO2 concentrations (44 and 107 nl 1-1), but increased by the relatively higher SO2 concentrations (231 and 441 nl 1-1). Increasing NaCl concentrations significantly reduced plant growth and grain yield. Severe NaCl salinity caused a substantial decrease in root growth, due to the effect of high Na+/Ca2+ ratio, resulting in an increase in Mild NaCl salinity initially decreased shoot growth, resulting in a decrease in shoot to root ratio, but later a shoot to root ratio. significant decrease in root growth developed, resulting in an increase in shoot to root ratio. The effects of SO2 fumigation and NaCl salinity on plant dry weights and shoot to root ratios were mostly additive, except that dry weight in plants subject to mild NaCl salinity was decreased less by 441 nl 1-1 SO2 fumigation than the nonsaline plants. Exposure to 231 nl 1-1 SO2 increased shoot to root ratio in plants with mild NaCl.
To understand physiological mechanisms behind the negative growth responses to SO2 fumigation, NaCl salinity and their combinations, stomatal conductance, sulphur and salt accumulation, photosynthesis, carbohydrate concentrations, and nitrogen metabolism parameters were examined in long-term fumigation experiments under near-ambient conditions.
In the long-term exposure to increased SO2 concentrations, the responses of plant growth and yield were negatively correlated with SO2 concentrations, but not with concentrations of sulphur in plant tissues. Plants exposed to low (107 nl 1-1) and relatively higher concentrations of SO2 (441 nl 1-1) had similar concentrations of sulphur in leaves. Reductions in growth and yield in plants exposed to higher concentrations of SO2 resulted from SO2 toxicity to physiological processes, such as nutritional and ionic balances, photosynthesis, and nitrogen metabolism. Exposure to 441 nl 1-1 SO2 significantly decreased stomatal conductance, net photosynthesis rate, and carbohydrate availability, which contributed an increase in shoot to root ratio. SO2 increased sulphate anion concentration which significantly disturbed ionic balance, causing increased K+ and decreased Na2 + , Ca2+ and CP concentrations and the nitrogen/sulphur balance in plant tissues. Although SO2 fumigation did not affect nitrogen uptake rate, it changed nitrogen distribution, nitrate reductase activity in leaves, soluble protein content and concentrations of total amino acids in plant tissues.
Salt toxicity and secondary physiological damages contributed to growth and yield reductions in plants subject to prolonged NaCl Increasing NaCl concentrations caused excessive salt (C1-, Na+) accumulation in plant tissues, and decreases in Although net photosynthesis rates in the youngest fully expanded leaves were little affected by NaCl salinity, long-term exposure to NaCl salinity decreased nonstructural carbohydrate concentrations in plant Cumulative salt injury may have caused a significant salinity stress. concentrations of K+ and sulphate anion. tissues. photosynthetic loss in old leaves and a decrease in total carbon gain in plants. Increasing NaCl salinity also significantly disturbed nitrogen metabolism in plants, by decreasing nitrogen uptake, altering nitrogen distribution, and increasing accumulation of total amino acids.
The nature of interactions between SO2 fumigation and NaCl salinity appeared to depend on their effects on the uptake and toxicity of SO2 and NaCl salt to physiological processes. Although severe NaCl salinity significantly decreased sulphur concentration in leaves of plants exposed to SO2, due to NaCl-induced increase in stomatal resistance, it decreased growth and yield in plants exposed to low SO2 concentrations and severe salinity. However, mild NaCl salinity that induced a slight increase in stomatal resistance, only slightly decreased leaf sulphur concentration in plants exposed to higher concentrations of SO2. Therefore mild NaCl salinity could not effectively protect plants against SO2 toxicity through reducing SO2 uptake in the long term, In contrast, exposure to 441 nl l-1 SO2 significantly decreased Cl' and Na+ concentrations, but increased K+ concentrations in leaves of plants subject to long-term mild salinity stress, which decreased salt toxicity to physiological processes.
Fumigation with SO2 concentrations of less than 441 nl 1-1, additively affected photosynthesis, carbohydrate production, and nitrogen metabolism parameters in plants subject to long-term NaCl salinity. Exposure to 441 nl 1-1 SO2 and mild NaCl salinity had antagonistic interactions on physiological responses, such as carbohydrate concentrations and nitrogen metabolism parameters. Plant tolerance to the long-term NaCl salinity was enhanced by 441 nl 1-1 SO2 fumigation by decreasing Na+ and CF concentration and increasing K+ concentration in leaves, and salt toxicity to physiological processes, resulting in antagonistic interactions on growth and yield. It is concluded that increasing NaCl salinity could not effectively protect plants against SO2 toxicity on physiology and growth by increasing leaf stomatal resistance, in the wheat plants exposed to a long-term simultaneous SO2 fumigation under ambient conditions. The two stresses are most likely to additively affect physiological responses, growth and yield in wheat plants in the long term. However, relatively higher SO2 fumigation appeared to protect the saline plants from salt toxicity to physiological processes and eventual growth, through decreasing stomatal conductance and salt concentrations in plant tissues. The effects of SO2 fumigation, NaCl salinity and their combination on the physiological responses to eventual growth in plants are discussed in the context of conceptual models.
26
Mchabe, Dursman. "Sulphur self–retention and sulphur dioxide capture with active calcium minerals in mineral–rich coals / Mchabe, D". Thesis, North-West University, 2011. http://hdl.handle.net/10394/7037.
Testo completoAbstract (sommario):
In order to provide information for the development of clean coal technology, the
sulphur self–retention and sulphur dioxide capturing properties of minerals present in
low grade coals was investigated. This study consisted of detailed mineral analyses of
coal and ash samples using results obtained from QEMSCAN and separate retention
(coal) and capture (ash) experiments with laboratory scale reactors. Typical South
African coal samples were used in this study. The ash content varied between 37.0 wt
% and 47.9 wt % with active calcium oxide (from calcite and dolomite) present
between 1.22 wt % and 4.92 wt %. The total sulphur content ranged between 0.60 wt
% and 1.90 wt % and was distributed between sulphate minerals, pyrite and
organically associated minerals in the coal macerals. The calcium to sulphur ratio
based on the active calcium ranged from 0.64 to 3.20. Sulphur self–retention
experiments (using powders of particle sizes ranging from 212 um to 300 um) were
carried out in a Packed Bed Balance Reactor at 900 oC at atmospheric pressure with
dry air for a period of 12 h. Transformation of a large fraction of the calcium bearing
minerals to sulphates was evident with total sulphur self–retention between 22.9% and
66.9% and the formation of calcium containing non–crystalline phases.
Thermogravimetric Analyzer experiments using 1 mm diameter coal particles were
carried out with the ash prepared (in situ with air) prior to the actual sulphation
determinations. After attaining a stable ash mass, the gas stream was changed to the
sulphur dioxide containing mixture (3000 ppm SO2, 8.0% CO2, 8.0% O2 and 83.7%
N2) and the increase in mass as a result of the reaction of sulphur dioxide (and
oxygen) with calcium oxide (calcite and dolomite) was recorded. Conversion of active
calcium bearing phases in the presence of sulphur dioxide containing gas mixture,
similar to the gas released during fluidised bed combustion, was employed to evaluate
the desulphurisation potential of the coal ashes, and it was found that nearly 40% of
the active calcium oxide was converted after 90 min reaction time at 900 ºC and that
no blocking of pores occurred as a result of solid phase changes. A mathematical
model based on the shrinking core model with diffusion through the product layer as
the determining mechanism was found to describe the overall reaction rate.Thesis (M.Ing. (Chemical Engineering))--North-West University, Potchefstroom Campus, 2012.
27
Henry, William John. "Annelation and pyrolysis reactions of 3-thiabicyclo[3.2.0]heptane-3,3-dioxide ring systems". Thesis, University of Edinburgh, 1987. http://hdl.handle.net/1842/15006.
Testo completo
28
Blackie, Douglas Sinclair. "Sulphur dioxide : high resolution UV photoabsorption cross sections at 198 K". Thesis, Imperial College London, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.508327.
Testo completo
29
Hunt, Gillian A. "Environmental modification of the responses of vicia faba to sulphur dioxide". Thesis, Loughborough University, 1989. https://dspace.lboro.ac.uk/2134/12479.
Testo completo
30
Ngeleka, Tholakele Prisca. "Sulphur dioxide capture under fluidized bed combustion conditions / Tholakele Prisca Ngeleka". Thesis, North-West University, 2005. http://hdl.handle.net/10394/1416.
Testo completoAbstract (sommario):
An investigation was undertaken to determine the feasibility of increasing the hydrogen
production rate by coupling the water gas shift (WGS) process to the hybrid sulphur process
(HyS). This investigation also involved the technical and economical analysis of the water gas
shift and the H2 separation by means of Pressure swing adsorption (PSA) process. A technical
analysis of the water gas shift reaction was determined under the operating conditions selected
on the basis of some information available in the literature. The high temperature system (HTS)
and low temperature system (LTS) reactors were assumed to be operated at temperatures of
350ºC and 200ºC, respectively. The operating pressure for both reactors was assumed to be 30
atmospheres. The H2 production rate of the partial oxidation (POX) and the WGS processes was
242T/D, which is approximately two times the amount produced by the HyS process alone. The
PSA was used for the purification process leading to a hydrogen product with a purity of
99.99%. From the total H2 produced by the POX and the WGS processes only 90 percent of H2
is recovered in the PSA. The unrecovered H2 leaves the PSA as a purge gas together with CO2
and traces of CH4, CO, and saturated H2O. The estimated capital cost of the WGS plant with
PSA is about US$50 million. The production cost is highly dependent on the cost of all of the
required raw materials and utilities involved. The production cost obtained was US $1.41/kg H2
based on the input cost of synthesis gas as produced by the POX process. In this case the
production cost of synthesis gas based on US $6/GJ for natural gas and US $0/Ton for oxygen
was estimated to be US $0.154/kg. By increasing the oxygen and natural gas cost, the
corresponding increase in synthesis gas has resulted in an increase in H2 production cost of US $1.84/kg.Thesis (M.Sc. (Chemical Engineering))--North-West University, Potchefstroom Campus, 2006.
31
Mansfield, Philippa Jane. "Interactions of atmospheric sulphur dioxide with fungal diseases of winter barley". Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47554.
Testo completo
32
Hlabano-Moyo, Bongibethu Msekeli. "Separation of SO2/O2 using membrane technology / Bongibethu Msekeli Hlabano-Moyo". Thesis, North-West University, 2013. http://hdl.handle.net/10394/9447.
Testo completoAbstract (sommario):
The Hybrid Sulphur process is one technology out of a multitude of known technologies responsible for hydrogen production. Within the latter hydrogen production cycle, it is pivotal to recover O2 as a by-product from a sulphuric acid decomposition reaction that produces SO2, H2O and O2. It is assumed that a simple phase separation stage carried out on the reaction products would liberate SO2 and O2 as a gaseous mixture leaving behind H2O in the liquid state.
Several separation technologies are available to effect SO2/O2 separation, but membrane technology has proved to be dearer due to simplicity of the technology, low capital and energy costs. It is a pity though that insignificant work has been done that considers the SO2/O2 binary system in the membrane technology context. Of the insignificant work done, non – commercial membranes were employed. It is on the latter background that the present study was proposed.
Six commercial membranes were selected from literature, two (Udel Polysulfone and Teflon AF 2400) of which are currently used in gas separation applications and the remainder (Hyflon M, Hyflon F, Halar and Nafion 117) not necessarily used as gas separation membranes but present a potential of separating SO2/O2. The inclusion of the latter four membranes sought to unearth unknown gas separation potentials of the membranes based on hypothetical 1 μm thick membranes.
A screening technique was employed to eliminate poor performing membranes through pure component permeation of SO2, O2, N2 and CO2. The use of the additional gases (N2 and CO2) was meant to allow the generation of a pool of data that would be used as a yardstick to compare to literature and thus validate the authenticity of the designed set up. The single permeation experiments were carried out at 25°C and at absolute gas feed pressures of 1 bar, 2 bar and 3 bar, with the exception of Hyflon F experiments that were carried out at 3.85 bar, 2.85 bar and 1.85 bar also at 25°C. The effect of pressure on gas permeability and ideal selectivity of all gases against O2 was investigated. Udel Polysulfone and Nafion 117 presented clearly evident pressure dependant SO2 permeabilities whilst CO2, N2 and O2 permeabilities were sluggishly dependant on pressure in all membranes. Gas flux in general increased with increasing pressure as pressure is essentially the driving force for permeability. Membrane screening for further investigation was then performed based on a compromise between SO2/O2 ideal selectivity and SO2 flux in hypothetical 1 μm thick membranes. Membranes that presented the best SO2/O2 selectivity include, Udel Polysulfone with SO2/O2 selectivities of 46, 58 and 314 at 1 bar, 2 bar and 3 bar respectively, Nafion 117 with SO2/O2 selectivities of 30, 35 and 40 at 1 bar, 2 bar and 3 bar respectively and Halar with a SO2/O2 selectivity of 17 at 3 bar. The best SO2 flux through hypothetical 1 μm thick membranes was manifested in Teflon AF 2400 with SO2 fluxes of 3.6 m3.m-2.hr-1, 5.9 m3.m-2.hr-1 and 9.9 m3.m-2.hr-1 at trans-membrane pressures of 1 bar, 2 Bar and 3 Bar respectively, Udel Polysulfone with SO2 fluxes of 0.13 m3.m-2.hr-1, 0.32 m3.m-2.hr-1 and 2.56 m3.m-2.hr-1 at trans-membrane pressures of 1 bar, 2 bar and 3 bar respectively and Nafion 117 with SO2 fluxes of 0.48 m3.m-2.hr-1, 1.03 m3.m-2.hr-1 and 1.79 m3.m-2.hr-1 at 1 bar, 2 bar and 3 bar trans-membrane pressures respectively. Despite Teflon AF 2400 presenting the highest SO2 flux, the poor SO2/O2 ideal selectivity ≈ 1 rendered the membrane unfit for further investigation. The low SO2 flux (0.02 m3.m-2.hr-1) presented by Halar also rendered the membrane unfit for further investigation despite the relatively fair SO2/O2 ideal selectivity of 17.
Binary permeation experiments were then performed on Udel Polysulfone and Nafion 117 after passing the single permeation screening test. Gas mixture compositions of (25 wt %:75 wt %, SO2:O2), (50 wt %:50 wt %, SO2:O2) and (75 wt %:25 wt %, SO2:O2) were employed. The binary permeation experiments were carried out at a temperature range of 15°C to 55°C and a SO2 feed partial pressure range of 1.1 ± 0.1 bar to 2.3 ± 0.1 bar.
The SO2 permeate composition increased with pressure and decreased with temperature in both Udel Polysulfone and Nafion 117. Udel Polysulfone presented a superior SO2/O2 separation potential, concentrating a (25 wt %:75 wt %, SO2:O2) gas mixture to (94 wt %:6 wt %, SO2:O2) in a single step at 15°C and 2.2 ± 0.1 bar SO2 feed partial pressure. Nafion 117 concentrated the same gas mixture to (87 wt %:13 wt %, SO2:O2) also in a single step at 15 °C and 2.4 ± 0.1 bar SO2 feed partial pressure. Based on hypothetical 1 μm thick membranes, Nafion 117 presented generally high SO2 molar fluxes in mixture with O2 of about a magnitude higher than the SO2 molar fluxes presented in Udel Polysulfone. Also, Nafion 117 proved to be less prone to plasticisation within the pressure range considered. Despite Udel Polysulfone presenting generally lower SO2 molar fluxes, Udel Polysulfone was deemed to be the ideal membrane for the current SO2/O2 separation application as thicknesses of 1 μm of Nafion the perfluorosulfonic acid based membrane are currently unknown and also Udel Polysulfone presented the best SO2/O2 separation capability. The latter findings are envisaged to prompt further research on the production of ultra-thin perfluoro-sulfonic acid based membranes for the current application.Thesis (MIng (Chemical Engineering))--North-West University, Potchefstroom Campus, 2013
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Rakowsky, Ademar R. "Simulations of the sulphur chemistry of a convective cloud". Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66090.
Testo completo
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Thornton, David Phillip. "The New Zealand National Environmental Standards for ambient air quality: analysis and modelling case study". Thesis, University of Canterbury. Geography, 2007. http://hdl.handle.net/10092/1501.
Testo completoAbstract (sommario):
Historically, the New Zealand rationale behind air quality management has been to adopt an effects-based approach based on environmental impacts. Generally, this method has been efficient in that it permitted emitters to decide how to minimise and mitigate impacts. However, to address the inconsistencies in air quality management across New Zealand born of this approach, and to permit measures designed to improve the working of the Resource Management Act (RMA), National Environmental Standards for Ambient Air Quality have been developed and implemented to establish consistent regulation and protection for all New Zealanders. The standards were gazetted in September 2004, for full implementation by 2013. This thesis explores the implementation of the National Environmental Standards for Ambient Air Quality, examining the philosophy behind the standards and associated strategies for dealing with air pollution management in New Zealand, and the international context for the development of appropriate tools to address air quality concerns. The research also provides an independent dispersion modelling assessment of the application of the Ministry for the Environment's initiative regarding sulphur dioxide in the Marsden Point airshed, Northland, utilising The Air Pollution Model (TAPM) for a period when heightened concentration values had been recorded. The key outcomes of the thesis are: (i) 99.9th percentile and maximum values for the simulated two-day modelling case study are within those stipulated by the air quality standards for sulphur dioxide; (ii) modelled concentrations associated with shipping within the airshed of interest contribute significantly to total modelled values; (iii) the chief obstruction to increased use of the prognostic modelling approach is that of the unsatisfactory availability and integrity of emission inventories; (iv) performing long-term high-resolution simulations with multiple point sources is prohibitive due to computational demands; (v) good quality monitoring will always be required; (vi) the standards have broad and far-reaching implications for resource managers, resource users and possibly the economy of individual regions and the country as a whole; (vii) the successful implementation of the National Environmental Standards for Ambient Air Quality in New Zealand will integrate a thorough understanding of modelling, measurements, meteorology and emissions.
35
Small, Andrew Alexander. "The influence of air pollution on the transmission of Barley Yellow Dwarf Virus by Rhopalosiphum padi (L.)". Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313997.
Testo completo
36
McCormick, Brendan Thomas. "Measuring volcanic sulphur dioxide degassing with the satellite-based Ozone Monitoring Instrument". Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648608.
Testo completo
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Wright, E. A. "The effects of sulphur dioxide and nitrogen dioxide, singly and in mixture, on the growth of birch trees". Thesis, Lancaster University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372938.
Testo completo
38
Citrone, Sharon Deborah. "The effects of sulphur dioxide and nitrogen dioxide on the relationship between Auchenorrhyncha species and their host plants". Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/47809.
Testo completo
39
Hayer, Catherine S. L. "Observations of sulphur dioxide emissions from the Soufriere Hills Volcano, Montserrat, W.I". Thesis, University of Reading, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.631704.
Testo completoAbstract (sommario):
The flux of sulphur dioxide (S02) gas has been used as an indicator of the eruptive activity and reservoir degassing of volcanoes around the globe and specifically during the eruption of Soufriere Hills Volcano on Montserrat, W.I., which has been semi-continuous since 1995. During this study, S02 emission rates measured using ground- and satellite-based instruments were used to evaluate the strengths and weaknesses of two ultraviolet instruments: the satellite-based Ozone Monitoring Instrument (OMI) and a ground-based Differential Optical Absorption Spectrometer (DOAS) instrument array, during two phases of lava extrusion in 2008-2010. An apparent increase in the amount of S02 observed by OMI during lava extrusion compared to quiescence was not observed by the DOAS array. This led to the conclusion that the volcanic S02 plume is located higher in the atmosphere during increased volcanic activity, as a result of a variety of volcanic processes, making it easier to observe from space than from the ground. Measurements from the satellite-based Infrared Atmospheric Sounding Instrument (IASI) show similar trends over temporally-averaged periods to OMI but IASI gives values of S02 emission about 600 tonnes/day lower.
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Pilkington, Bridget Jane. "Phospholipid composition of Saccharomyces cerevisiae and Zygosaccharomyces bailii and their response to sulphur dioxide". Thesis, University of Bath, 1989. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234034.
Testo completo
41
Dursun, Sukru. "The effects of sulphur pollution on soil fungi and decomposition of tree leaf litters". Thesis, Cardiff University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321745.
Testo completo
42
Tomlinson, David. "Stability of catalytic plate reactors". Thesis, University of Newcastle Upon Tyne, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337374.
Testo completo
43
Ansuategi, Alberto. "Economic growth and environmental quality : a critical assessment of the environmental Kuznets curve hypothesis". Thesis, University of York, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326770.
Testo completo
44
MacMillan, Douglas C. "Valuing the environmental benefits of reduced acid deposition in the semi-natural environment". Thesis, University of Stirling, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244698.
Testo completo
45
Macdonald, Anne Marie. "Sulphur dioxide oxidation in a rainband : effects of in-cloud hydrogen peroxide production". Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=55616.
Testo completo
46
Wookey, Philip Andrew. "Effects of dry deposited sulphur dioxide on the decomposition of forest leaf litter". Thesis, Lancaster University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328496.
Testo completo
47
Kargiolaki, Hariklia. "The response of poplar clones to atmospheric pollution by ozone and sulphur dioxide". Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.253283.
Testo completo
48
Bosac, Creana. "The impact of ozone and sulphur dioxide on reproductive development in oilseed rape". Thesis, University of Nottingham, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306618.
Testo completo
49
Dicey, M. "The effect of cold maceration with and without sulphur dioxide on pinot noir wine". Lincoln University, 1996. http://hdl.handle.net/10182/1057.
Testo completoAbstract (sommario):
The effects of varying levels of sulphur dioxide (SO₂) on the cold maceration process was investigated with Pinot noir (Vitis vinifera L.) wine. The effects of these varying levels on the wines composition and colour parameters were examined. Cold maceration is a technique whereby grapes are crushed and placed at low temperatures (4 - lO°C) in the presence 50 - 150 mgL⁻¹ SO₂. This process is believed to provide a medium for the extraction of water soluble phenolic compounds, rather than the alcoholic extraction employed in normal fermentations. The extraction of these phenolic compounds was monitored from the juice through to six months of bottle age. The changes were measured using both Spectrophotometric and High Performance Liquid Chromatographic (HPLC) procedures. Cold maceration wines were found to be not significantly different to the control wine in all compositional parameters other than titrateable acidity which was found to be less than the control for all the cold maceration wines. The unsulphured cold maceration wine was not significantly different from the control wine in any of the spectral measurements except natural degree of ionisation, in which it was higher, and total phenolics, in which it was lower. These results indicate that the cold maceration process alone does not alter the extraction of phenolic compounds. The HPLC analysis of the wine confirmed the spectral results indicating that their were no significant differences in the levels of extraction of anthocyanins. The sulphured cold maceration wines were significantly greater than the control in visible colour, colour density, total anthocyanins, natural degree of ionisation, ionised anthocyanins and total phenolics. These results followed similar patterns with wine ageing, at six months these wines were still significantly greater in all the measurements apart from natural degree of ionisation. The results for the sulphured cold maceration wines indicates that SO₂ is acting as a solvent for the extraction of phenolic compounds including anthocyanins. The 50 mgL⁻¹ SO₂ cold maceration wine had similar colour and phenolic content to the 100 mgL⁻¹ SO₂ cold maceration wine at bottling, at six months the 50 mgL⁻¹ SO₂ cold maceration wine still retained a similar colour to the 100 mgL⁻¹ SO₂ cold maceration wine but had vastly reduced anthocyanin content. This indicates that for the grapes utilised in this study the most appropriate level of addition at cold maceration would be 50 mgL⁻¹ of SO₂. With grapes of differing phenolic content the level of addition required will vary.
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Shawki, Dilshad. "South Asian precipitation response to regional sulphur dioxide emissions in a global climate model". Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/51093.
Testo completoAbstract (sommario):
Aerosols have an inhomogeneous distribution across the globe because of their short lifetimes in the atmosphere. They impose a localised radiative forcing close to their emission source that is effective at driving circulation changes and influencing the hydrological cycle. One such type of circulation that has recently been suggested to be affected by aerosols is the South Asian summer monsoon, which provides 80% of annual rainfall to over a billion people during the summer months. I used the UK Met Office HadGEM3 coupled global climate model to investigate, for the first time, the centennial-scale South Asian precipitation responses to removing regional anthropogenic sulphur dioxide emissions. This study is unique since these experiments have never been attempted on a scale that is multi-regional, centennial and in a fully coupled ocean-atmosphere model setup. Despite the imposed localised heating in my experiments resulting from emissions removals over the United States, Europe, East Asia, South Asia or the northern mid-latitudes as a whole, the large-scale spatial pattern and magnitude of the precipitation response over South Asia was similar for all experiments. This was due to the ocean responding to the atmosphere enabling the full response to be realised and the ocean dynamics driving a structurally similar global climate response. The sum of the responses from the experiments where the emissions are removed from the United States, Europe and East Asia resemble the response seen in the experiment where emissions are removed in the entire northern mid-latitude band, suggesting that the response is roughly linear, with East Asia being the largest contributor to the response. East Asia’s proximity to South Asia meant that it was more effective at influencing the land-sea thermal contrast, pressure gradients, and therefore the local monsoon circulation itself. On the other hand, local emissions removals, i.e. over South Asia itself, led to decreases in precipitation over central and northern India, a result not seen in any other experiment. Moreover, the response of the circulation was still found to be the main driver of the response in this case, despite changes to the clouds making them thinner and less reflective. In the future, further work is warranted to allow for comparisons with other coupled ocean-atmosphere models performing similar multi-regional experiments, to enhance confidence in our results and to further our understanding of the processes involved. Similar experiments can also be performed to explore the role of other short-lived pollutants, such as tropospheric ozone. The insight provided could prove invaluable for informing emissions reduction policies and for understanding the implications for short-term regional climate prediction.