No description available.

<p>The objectives of this project was to ameroliate two waste materials, namely Acid Mine Drainage and Fly Ash and recover the solid residues for conversion into an adsorbent to treat brine. The solid residues were then converted into zeolite P through low temperature hydrothermal treatment. The adsorption capacity of the solid residues, zeolite P derived from the solid residues was compared to the commercial zeolite Y and fresh Arnot fly ash. The quality of the resulting water was assessed using different analytical methods before the reaction with adsorbents and after the reaction and a comparison was done based on the removal efficiency of elements Zeolite P from solid residues was successfully synthesized as confirmed by XRD, BET and FTIR. Brine treatment with fly ash, solid residues, zeolite P and commercial zeolite Y adsorbents was done concentration on the following major elements Na, K, Mg, Ca and Si. Zeolite P had higher or similar removal efficiency that the commercial zeolite Y for the following elements K, Ca and Mg. Fly ash is the only adsorbent that managed to reduce the concentration of Na in brine and also had a good removal efficiency of Mg. Si leached out of all the adsorbents which could be ascribed to Si being the major component of these adsorbents which could indicate some dissolution of these adsorbents under the conditions tested. Overall, zeolite P did not completely remove the major elements, especially for Na, but did result in a cleaner waste stream which would improve brine processing.</p>

No description available.

The application of a wide range of computational methods to several problems in zeolite chemistry is explored in this thesis. Symmetry-constrained lattice energy minimisations have been performed on a series of pure silica polymorphs using the shell model for silicates and quantitative agreement is found between the experimental and calculated structures. The computed lattice energies of the silicas are found to be between 8 and 20 kJmol^-1 less stable than quartz. The energies are found to be directly dependent on the densities of the structures and show good agreement with a recent calorimetric study. A new forcefield for aluminophosphates based on the shell model has been obtained by fitting to the structure and properties of berlinite and lattice energy minimisation calculations have been carried out on a series of aluminium phosphate polymorphs. The experimental structures are reproduced to a reasonable accuracy, especially in cases where high quality crystallographic data are available on calcined structures. In cases where experimental methods give conflicting results regarding the space group symmetry, calculated structures having lower symmetry than those observed in the crystallographic studies are suggested. An approximately linear dependence of lattice energy on density is again observed; the computed lattice energies are found to span a range of 11.7 kJmol^-1 higher than berlinite, which compares to an experimentally determined range of 9.7 kJmol^-1. Proton binding calculations have been performed on the structure of H-SAPO-37 to determine the most favourable binding proton sites. The calculations correctly reproduce the sites which have the highest fractional occupancies in a crystallographic study. Molecular dynamics simulation has been used to study the diffusion of xenon in ferrierite and zeolite-L. It was found that at 298K and a loading level of 1.33 atoms per unit cell, diffusion down the tenring channel in ferrierite is a more facile process than down the wider twelve-ring channel in zeolite-L (D=8.90xl0^-9 m²s^-1 for ferrierite versus 1.78xl0^-9 for zeolite-L). This effect can be rationalised by consideration of the effect of channel shape on the diffusion pathway. Under the same conditions, the interaction energy was calculated to be more favourable for ferrierite (ΔU=-25.7 kJmol^-1 versus -20.0 kJmol^-1). A new forcefield for the interaction of hydrocarbons and aromatics with siliceous zeolites was fitted to thermochemical and crystallographic data. The forcefield successfully reproduced the crystallographically determined positions of pyridine and propylamine in siliceous ferrierite and dodecasil-3C. In addition, quantum mechanical calculations were used to fit a forcefield for the interaction of benzene with cation-containing zeolites. Molecular dynamics calculations were used to study the transport of benzene in siliceous faujasite. The coupling of lattice vibrations to the benzene molecule was found to enhance the mobility (for example, at 298K, D=0.11xl0^-9m²s^-1 with a fixed lattice compared to D=0.31xl0^-9m²s^-1 with aflexible lattice). Two diffusion regimes were observed corresponding to intra- and inter-cage benzene mobility which correlate well with hypothetical hopping pathways. Analogous pathways for benzene in cation-containing zeolites have shown that cation sites act as traps for the benzene in Na-X and Na-Y, which reduce the mobility compared to the siliceous case. In Na-X, the pathways are further modified by the addition of extra cation sites that act to reduce the hopping activation energy and therefore enhance the diffusion. This behaviour is consistent with observed trends in experimentally determined diffusivities.

The potential of granular zeolites as a heating medium for drying corn was evaluated in a batch type experimental dryer. At temperatures from 150-250$ sp circ$C and residence times of 3-8 minutes, synthetic zeolites (4A and 13X) removed 9-18 percentage points from the initial moisture of corn. These values were about double those of sand, the most commonly used particulate medium. / Using an adiabatic dryer, the kinetics of moisture sorption in corn-zeolite mixtures was investigated. The heating medium in this part of the study was a natural zeolite (chabazite) and the corn was yellow dent type. Diffusivity values for corn were 1.012 $ times$ 10$ sp{-5}$ $-$ 3.127 $ times$ 10$ sp{-5}$ cm$ sp2$/s with zeolite at temperatures of 140-220$ sp circ$C. These values are much smaller than those for zeolite. Therefore, it is believed that the diffusion of moisture in corn itself is the main resistance to the transfer of moisture. The heat transfer coefficient between corn and zeolite was found to be in the range of 50-312 W/m$ sp2 cdot$K. Luikov's model for simultaneous heat and mass transfer was applied to corn-zeolite mixtures and the equations were solved by the Numerical Method of Lines (NMOL). These numerical solutions agreed closely with the experimental data. / The processed corn was subjected to in vivo and chemical analyses. Results of feeding experiments using laboratory rats did not indicate that the nutritive quality of the processed corn was adversely affected. Similarly, the acid detergent fibre analysis did not show a significant reduction in the availability of corn protein.

Thesis (Ph. D.)--University of Washington. / Bibliography: l. 81-83.

Thesis (M.S.)--Ohio University, June, 2001. / Title from PDF t.p.

Diss. (sammanfattning) Luleå : Luleå tekniska univ., 2004. / Härtill 7 uppsatser.

Thesis (M.Sc.). / Written for the Dept. of Bioresource Engineering. Title from title page of PDF (viewed 2008/05/30). Includes bibliographical references.

Thesis (M.S.)--West Virginia University, 1998. / Title from document title page. Document formatted into pages; contains xi, 84 p. : ill. Includes abstract. Includes bibliographical references (p. 64-67).