Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 97-102). Also available via the Internet.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1990. / Vita. Abstract. Includes bibliographical references (leaves 186-199). Also available via the Internet.

Thesis (Ph. D.)--Oregon State University, 1994. / Typescript (photocopy). Includes bibliographical references (leaves 104-111). Also available via the World Wide Web.

Thesis (Masters Diploma (Mechanical engineering)--Cape Technikon, Cape Town, 1993 / The main objective of the work outlined in tills project is to create an awareness of Pressure Swing Adsorption (PSA) Processes, their application to oxygen production systems in the RSA and the construction and testing of a pilot plant, built to assess an overseas design. Available oxygen PSA technology was examined from a theoretical approach, right through to practical applications. The aim was not to re-invent the technology, but to review what technology is available and to assess its suitability for the South African Industrial Sectors. This was undertaken by investigating all PSA processes that are available to market the product to industry. The technology review includes an investigation of overseas PSA technologies and compares these modes of technology with the technology that is readily available to Afrox Limited, a major gas supplier in South Africa. This resulted in the technology from the British Oxygen Company being thoroughly reviewed, examined and compared to various other modes of technology. The basic principals of adsorption are discussed to give the reader an understanding of the factors that influence efficient adsorption and adsorbent regeneration. The parameters that defme when adsorption separation processes are applicable to the separation of atmospheric gases are also discussed. The different types of PSA plant layout are discussed in great detail and it is explained when each plant layout type would be used.

A new apparatus for the determination of adsorption isotherms is described. The chief feature of this apparatus is that the gas under investigation is allowed to leak slowly, at a known rate, into the adsorbent. The rate at which the pressure increases in the system is recorded. From this data the amount of gas adsorbed by the solid can be calculated and with the measured pressure can be plotted as an adsorption isotherm. The adsorption of carbon dioxide on charcoal has been studied by the use of this apparatus. The reported presence of discontinuities in this adsorption isotherm has not been confirmed. / Science, Faculty of / Chemistry, Department of / Graduate

In this thesis various physicochemical factors which determine the characteristics of latex agglutination immunoassays are examined. A model of antibodies reacting with antigen (bovine serum albumin; BSA) adsorbed to the surface of polystyrene latex (PSL) beads was examined. The adsorption studies of BSA to PSL showed that the mass of BSA adsorbed at saturation depends on the type of polystyrene latex. Latexes with highly hydrophobic surfaces adsorbed more BSA molecules than those with lower hydrphobicity. Desorption studies showed that latexes that maximize adsorption lost the lowest fraction of their bound BSA molecules following extensive buffer wash. Partial desorption of BSA from PSL was achieved by the addition of detergent, whereas the addition of more BSA molecules or other macromolecules such as PEG or IgG did not displace the adsorbed BSA molecules. Examination of the material removed from the surface of the latexes by SDS-PAGE analysis showed that the composition of the adsorbed layer was enriched in the higher molecular weight oligomers of BSA, relative to their concentrations in the stock solution. A model in which adsorbed protein is assumed to undergo a polymerization reaction provides a general explanation of the observed results. Studies of polyclonal antibody (anti-BSA IgG) binding to antigen-coated PSL showed that the surface concentration of bound antibody depends on the surface concentration of antigen on the latex particles and on the availability of PSL surface area not occupied by antigen. Analysis of shear induced aggregation results show that for low surface coverage of latex particles by protein antigen in stable suspension, relatively low concentrations of specific antibodies are required to cause agglutination. Increasing surface density of antigen requires significantly higher concentrations of specific antibodies to produce agglutination. For a given surface coverage of antigen, results show that increasing the shear rate decreases the antibody concentration necessary to produce a given degree of agglutination. A remarkable structure formation and long range ordering exhibited by floes of latex coagulating in salt under intermediate shear rates was observed. This structure formation was not observed during antibody-induced agglutination under shear. / Science, Faculty of / Chemistry, Department of / Graduate

A single Fe³⁺ species has been introduced into Linde L zeolite and is identified as an iron oxyhydroxide from its Mössbauer relaxation properties. The effects of N₂, CO₂ and C₂H₆ on the ferric species and on the bulk behaviour of the sample are observed by Mössbauer Spectroscopy and adsorption studies under outgassing conditions. The ferric oxyhydroxide initially blocks the pores to gas adsorption but reducing it to Fe⁰ at 943⁰ K and reoxidizing it to α-Fe₂0₃ in air at 773⁰ K frees the pores. The bulk α-Fe₂0₃ is concluded to lie on the external zeolite surface. / Science, Faculty of / Chemistry, Department of / Graduate

The investigation of gas-surface interactions has been approached from two different aspects. Firstly, the design and construction of an apparatus to measure low coverage isotherms for argon on evaporated metal films in the region of liquid nitrogen temperature is discussed. Secondly, a detailed analysis of available second and third order gas-solid interaction data has been carried out. It is found that the existing theories for interpreting and calculating three-body forces in physical adsorption systems are incapable of explaining the observed values. / Science, Faculty of / Chemistry, Department of / Graduate

The data of 14 soils were used to compute the ion activity product (IAP), the ratio of the ion activity product and to the solubility product (Ksp) of the pure minerals (IAP/Ksp) and to estimate the solid activity coefficients (SAC) of the soil components. The value of IAP and SAC of AlPO4 differs from soil to soil and increases with increasing P added to soil in acid soils and for calcium phosphate in basic soils. Magnesium apparently did not cause P adsorption or precipitation in the soils studied. The SAC of aluminum phosphate ranged from 10 to 10000 in acid soils. The mole fraction of the total phosphate in soil seemed to be a more satisfactory basis for calculating the concentration of the solid phase than was measurements of the available phosphate.

No description available.