Chan Siu-pang. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 45-47). / Abstract also in Chinese. / TITLE PAGE --- p.i / THESIS COMMUTE --- p.ii / ABSTRACT (English) --- p.iii / ABSTRACT (Chinese) --- p.iv / ACKNOWLEDGMENT --- p.v / TABLE OF CONTENTS --- p.vi / LIST OF FIGURES --- p.vii / LIST OF TABLES --- p.viii / Chapter CHAPTER 1. --- Introduction --- p.1 / Chapter Section 1.1. --- General Introduction --- p.1 / Chapter Section 1.2. --- Background Information --- p.2 / Chapter 1.2.1. --- Si(100) Surface --- p.2 / Chapter 1.2.2. --- Structure of Cl/Si(100) --- p.7 / Chapter Section 1.3. --- Etching of Si(100) by Chlorine --- p.9 / Chapter Section 1.4. --- Theory --- p.14 / Chapter Section 1.5. --- Computational Model --- p.17 / Chapter CHAPTER 2. --- Desorption Mechanism of SiCl4 --- p.19 / Chapter Section 2.1. --- Desorption Mechanism --- p.19 / Chapter 2.1.1. --- Trajectory1 --- p.20 / Chapter 2.1.2. --- Trajectory2 --- p.23 / Chapter 2.1.3. --- Trajectory3 --- p.26 / Chapter 2.1.4. --- Trajectory4 --- p.29 / Chapter 2.1.5. --- Trajectory5 --- p.32 / Chapter 2.1.6. --- Trajectory6 --- p.35 / Chapter Section 2.2. --- Discussion --- p.38 / Chapter Section 2.3. --- Conclusion --- p.44 / REFERENCES: --- p.45

Stable chlorine isotopes are useful geochemical tracers in processes involving the formation and evolution of evaporitic halite. Halite and dissolved chloride in groundwater that has interacted with halite in arid non-marine basins has a delta Cl-37 range of 0 +/- 3 parts per thousand, far greater than the range for marine evaporites. Basins characterized by high positive (-1 to +3 parts per thousand), near-0%, and negative (-0.3 to -2.6%) are documented. Halite in weathered crusts of sedimentary rocks has delta Cl-37 values as high as +5.6 parts per thousand. Salt-excluding halophyte plants excrete salt with a delta Cl-37 range of -2.1 to -0.8%. Differentiated rock chloride sources exist, e.g. in granitoid micas, but cannot provide sufficient chloride to account for the observed data. Single-pass application of known fractionating mechanisms, equilibrium salt-crystal interaction and disequilibrium diffusive transport, cannot account for the large ranges of delta Cl-37. Cumulative fractionation as a result of multiple wetting-drying cycles in vadose playas that produce halite crusts can produce observed positive delta Cl-37 values in hundreds to thousands of cycles. Diffusive isotope fractionation as a result of multiple wetting-drying cycles operating at a spatial scale of 1-10 cm can produce high delta Cl-37 values in residual halite. Chloride in rainwater is subject to complex fractionation, but develops negative delta Cl-37 values in certain situations; such may explain halite deposits with bulk negative delta Cl-37 values. Future field studies will benefit from a better understanding of hydrology and rainwater chemistry, and systematic collection of data for both Cl and Br.

<p>Chlorine is an essential building block in the environment and can be found in most places. Chlorine participates in a complex biogeochemical cycle and has been discussed for many years and it is well documented that natural chlorination of organic compound takes place in many parts of the ecosystem. Chlorine can be inorganic (Clin) and organically bound (Clorg). Previous studies have shown that the transformation of Clin to Clorg is connected with the amount of organic matter and the microbial activity in the soil. So far, studies have been focused on forest soil and there is a need for analysing the natural chlorination in other soil types. The aim of this study was to provide chlorination rates in agricultural soil which does not weem to have been done previously. Three common agricultural soils experiencing different agricultural practice and different cropping systems were incubated with Na36Cl at 20o C in a 56 days radiotracer experiment. The results show that a chlorination of 36Clin to 36Clorg in agricultural soil occurred and the Clorg levels increased over time. The chlorination rates ranged from 0,040 to 0,063 μg Cl g dry weight soil-1 d1. This was 10-fold lower than rates previously measured in coniferous forest soil. However, when expressed as μg Cl g dry weight organic carbon-1 d-1, rates in the agricultural soil was only slightly (at the most 2-fold) lower than in coniferous forest. This study contributes with new knowledge of natural chlorination rates in agricultural soil and gives further evidence that the natural chlorination can be connected to the amount of organic matter in the soil.</p>

Thesis (M.Sc.)(Microbiology)--University of Pretoria, 2006. / Includes summary. Includes bibliography. Available on the Internet via the World Wide Web.

No description available.

No description available.

Optical-electrical, rendering, paper-making, and sewage treatment plants emit odorous waste gases containing dimethyl sulfide (DMS) as one of the major odorous compounds. For the protection of ambient air quality and prevention of odor complaints, DMS should be eliminated from the gases before venting them into the atmosphere. This study aimed to develop a process for eliminating DMS in the waste gases by introducing an enough amount of chlorine gas to oxidize DMS therein to non-odorous dimethyl sulfone (DMSO2). The vented gas from the oxidation step is then contacted with a bed of granular activated carbon (GAC) to convert the residual chlorine to GAC-adsorbed hydrochloric acid and get a nearly odor-free gas. Both lab-scale and field tests were performed in this study. Results from the lab test indicate that the GAC had only an equilibrium DMS adsorption capacity of 4.30 mg/g GAC with 15-30 ppm DMS and no chlorine in the test gas. With an empty-bed gas-GAC contact time (EBCT) of around 0.49 s and no DMS in the test gas, 42 ppm gaseous chlorine could completely be reduced to HCl and the reduction product adsorbed to the GAC. The GAC had a minimum chlorine elimination capacity of around 110 mg/g GAC. Lab tests also indicate that with a molar Cl2/DMS ratio (R) of around 0.9 and a gas-phase reaction time of 5 s, and an EBCT of 0.58 s, the influent 22 ppm DMS could be removed to below detectable limits. Results from field tests in an optical-electrical wastewater plant show that by the developed process, < 1 ppm DMS in the plant¡¦s waste gas could be treated to an odor-free degree with a chlorine dose of 4-10 ppm.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references (leaves 255-268). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1961. / Bibliography: leaves 98-101.