A study has been made of the dissolution of naturally occurring α-iron oxide hydrate in acidified aqueous solutions of sulphur dioxide at 110°C. The dissolution was found to be independent of acidity at low concentrations of sulphur dioxide and inversely dependent on acidity at higher concentrations of sulphur dioxide. Both homogeneous and heterogeneous control of the reaction was observed. The addition of cupric ion to the system catalysed the rate. Dissolution is thought to occur via hydration of the oxide surface and subsequent reaction of undissociated sulphurous acid at the surface to form a ferric-sulphite complex. The rate determining step is considered to be the desorption of the complex from the surface. A limited study of the direct dissolution of iron oxide hydrate in sulphuric and perchloric acids at temperatures between 120 and 150°C is included. Under these conditions, the hydrated oxide surface is thought to undergo anion exchange during dissolution. Work carried out on the preparation and identification of the isomeric α- and γ-iron oxide hydrates is reported. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

Analysis of the sulfur dioxide long wavelength band, appearing in n-ROH or benzene and carbontetrachloride solutions, has been obtained in terms of the system:- donor + SO₂ ⇌ complex The characteristic constants for the MeOH , EtOH , n-PrOH, n-BuOH and benzene complexes and the heat of formation of the benzene and ethanol complexes with sulfur dioxide in carbontetrachloride have been estimated. Structures for the n-ROR – SO₂ complexes have been proposed along the lines of Mulliken's simple charge transfer theory. It has been shown that the spectroscopic behaviour of sulfur dioxide in mixed benzene - ethanol solutions is adequately explained in terms of the binary donor system:- benzene + SO₂ ⇌ (complex)₁ ethanol + SO₂ ⇌ (complex)₂ if it is assumed that the characteristic constants for both complexes and the molar extinction curve of free sulfur dioxide remains unchanged in passing from non - polar to polar solvents. From a similar analysis of the new band appearing in hydroquinone - sulfur dioxide - ethanol solutions, the characteristic constants and heat of formation of the hydroquinone - sulfur dioxide complex have been obtained. The value for the heat of formation of this complex is in good agreement with the reported value of the heat of decomposition of the hydroquinone - sulfur dioxide clathrate compound. This fact, together with the evidence of the binary donor character of the ethanol - benzene - sulfur dioxide system is strong evidence in favour of the proposed theory of the formation of liquid lattice penetration complexes (by penetration of the liquid lattice by sulfur dioxide). From studies of the temperature dependence of the long wavelength band in sulfur dioxide - water solutions, it has been concluded that neither Ley and Konig nor Boyd Campbell and Maass’ theories adequately describe the behaviour of the sulfur dioxide - water system. A new theory has been proposed which qualitively describes the behaviour of this system. However, attempts to obtain values for the constants involved from the absorption spectra of water-ethanol-sulfur dioxide solutions, have been unsuccessful. This has been attributed to the simultaneous formation of ethanol - water interpenetration complexes (water penetrating the ethanol lattice). / Science, Faculty of / Chemistry, Department of / Graduate

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

The growth of the layer formed on atomically clean lithium metal upon exposure to SO₂ gas is sequentially studied by controlling the quantity of gas reacted with the surface in a specially constructed vacuum system. A Fast Fourier Transform algorithm for the removal of instrumental broadening, and quantized and inelastic electron loss processes from the background of an Auger spectrum is presented. The deconvolved peaks for the S(LMM) and O(KKL) valence transitions are used to determine the molecular composition of the layer at each stage of its formation. The associated peak areas give the quantity of SO₂ reacted with the surface and the relative amounts of sulfur and oxygen present in each layer. The results indicate that two distinct layers of different composition are formed. The lower layer is a complete monolayer of Li₂O/Li₂S in a two-to-one ratio. The upper layer is thicker and consists of LiS₂O₄ and LiS₂O₃ in a 50% mixture. The formation of the upper layer is observed only after exposures of the surface to partial pressures of SO₂ greater than one millitorr. A model to explain the formation of the two layers and the observed pressure dependence is given. A flow method is used to study the kinetics of the Li-SO₂ reaction at submonolayer coverages. The pressure in a reaction vessel is monitored as a function of time when a fresh Li surface is exposed. A reaction order between 0.5 and 0.9 results, indicating that the surface of the scraped Li is energetically heterogeneous with respect to sites available for adsorption. An Arrhenius plot of the data indicates that the activation energy for the dissociative chemisorption to form the first monolayer lies between 2 and 5 kcal/mole. The sources for site heterogeneity and the activation energy are discussed. The resulting molecular model is used in combination with preliminary electrochemical results to compare the gas phase layer with the film formed on Li anodes in the Li/SO₂ ambient temperature battery. The model proves to be useful in explaining storage and discharge characteristics of the battery that are due to the presence of the anodic film.

The LINEATE IMAGING NEAR ULTRAVIOLET SPECTROMETER (LINUS) instrument has been used to remotely detect and measure sulfur dioxide (SO2). The sensor was calibrated in the lab, with curves of growth created for the 0.29 0.31 æ - spectral range of the LINUS sensor. Field observations were made of a coal burning plant in St. Johnâ s, Arizona at a range of 537 m. The Salt River Coronado plant stacks were emitting on average about 100 ppm and 200 ppm from the left and right stacks respectively. Analysis of the LINUS data matched those values within a few percent. Possible uses for this technology include remote verification of industry emissions and detection of unreported SO2 sources.