Thesis--University of Turku, 1983. / Also published in: Proceedings of the Finnish Dental Society, v. 79, 1983, Suppl. II. Includes bibliographical references (p. 60-62).

Erlangen, Nürnberg, Univ., Diss., 2003. / Dateien im PDF-Format. Computerdatei im Fernzugriff.

Erlangen, Nürnberg, University, Diss., 2003. / Dateien im PDF-Format.

Zugl.: Freiburg (Breisgau), University, Diss., 1999. / Lizenzpflichtig.

Thesis (M.A.)--Boston University / The extraction of uranium with O.lM trioctylphosphine oxide in cyclohexane in the presence of hydroxyethylethylenediaminetriacetic acid was shown to be most effective in the pH range from 0.5 to 1.5. A pH of 1.0 has been chosen as the working level for the extraction. It was found that under the above conditions uranium(VI) can be extracted quantitatively. The method used for the determination of uranium was based on the colorimetric method given by Horton and White in which dibenzoylmethane was used to form a colored complex in the presence of pyridine as a buffer agent in ethyl alcohol. The absorbances at the wave length 405 mu were measured. An interference study at a uranium concentration level of 0.050 mg. per ml. was made to find the tolerance level of various diverse ions of 0.500, 0.050 and 0.005 mg. per ml. concentrations. The metal ions that were studied were: aluminium(III), barium(II), bismuth(III), cadmium(II), cerium(III), chromium(III), cobalt(II), copper(II), iron(II), iron(III), lead(II), magnesium(II), manganese(II), nickel(II), potassium(I), silver(I), sodium(I), thorium(IV), zinc(II), and zirconium( IV). It was found that cerium (III), lead(II), thorium(IV) and zirconium(IV) interfered with the extraction of uranium under the above conditions. Triphenylphosphine sulfide was prepared, as described by Michaelis, by the direct addition of elementary sulfur to triphenylphosphine. Attempts were made to use triphenylphosphine sulfide as an extractant for the following metal ions: aluminium(III) bismuth(III), chromium(VI), copper(II), magnesium(II), manganese( VII), mercury(II), tin(II), and zinc(II). The results obtained indicated that triphenylphosphine sulfide did not extract the above metals.

A piston type of sampler was designed and constructed to sample the dispersed phase of a spray liquid-liquid extraction tower. The aim was to check a previous method of sampling the dispersed phase. This method depended on the use of a long probe which descended into the column from above and through which samples were removed by suction. Calculated values of the dispersed phase concentration using the piston type sampler were found to be generally lower than the corresponding concentrations using the dispersed phase probe. The system studied was methyl isobutyl ketone (the dispersed phase)-acetic acid (the solute) - water (the continuous phase). The solute was transfered from the aqueous phase, which was saturated with methyl isobutyl ketone, to the organic phase, which was saturated with water. Mass transfer data were gathered for this system in a 1.5-in. I.D. column which was approximately 7.3-ft. in height. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

Activities of Cu₂O in PbO - Cu₂O - SiO₂ slags have been measured by a slag-metal equilibrium. Excess properties of the cation were established from Temkin's rule using the measured Cu₂O and aO²⁻ data. Lnɤ Cu⁺ values were found to be directly proportional to the activities of silicate anions along lines of constant NPb²⁺/NCu⁺ ratio. Also, it was observed that the excess properties of the copper cation increase with cation dilution. These properties are generally characteristic of all metal cations in PbO-Cu₂O-SiO₂ and CaO-FeO-SiO₂ slags. A method has been devised for interpolation and extrapolation of measured activity data in ternary silicate slag systems. Integration of the cationic form of the Gibbs-Duhem equation in the PbO-Cu₂O-SiO₂ system has shown Toop's method of calculating ternary oxygen ion activities to be satisfactory. Agreement of the measured-cationic data with other data in the PbO-Cu₂O-SiO₂ system is good. The established cationic excess properties are structurally interpretable indicating that anionic and cationic activities, as predicted from ionic theory, are reasonable. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

An internal sampler, a plastic cup probe, was constructed to replace a funnel-probe for sampling the dispersed phase (methyl isobutyl ketone) in a liquid-liquid extraction spray column. The dispersed phase sample can be withdrawn from the column by the plastic cup probe without being contaminated with the continuous phase water. For runs in which the mass transfer is from the continuous phase to the dispersed phase, the plastic cup probe results agree with those obtained by the funnel-probe. On the other hand, for runs in which the direction of mass transfer is reversed, the plastic cup probe tends to give slightly lower dispersed phase concentrations than does the funnel-probe at the same sampling elevation. It is believed that both methods of measuring concentrations are correct within less than 2%. The effect of mass transfer on the axial dispersion coefficient of the continuous phase in a 1.5-in. I.D. liquid-liquid extraction spray column was studied for various superficial velocities of two phases, and for various partitionable solute (acetic acid) concentrations in the continuous phase fed to the column. Tracer solution (sodium chloride solution) was injected steadily into the continuous phase in the column. Axial concentration profiles of the tracer were measured upstream, with respect to the continuous phase, from the tracer distributor. The steady state form of the dispersion equation was used to calculate the axial dispersion coefficient of the continuous phase. The results obtained show that there is no effect of mass transfer on the axial dispersion coefficient within the range of the investigation. Drop size distribution and holdup of the dispersed phase in the column also were measured. The drop size distribution always shows two peaks. It was found that there is no effect of mass transfer on both the drop size distribution and on the dispersed phase holdups within the range of investigation. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

No description available.

There has been significant increase in production of copper treated lumber since a voluntary halt of chromated copper arsenate (CCA) for residential use by the wood treating industry. Disposal of copper treated wood wastes has become an environmental issue for companies using these products for residential applications. This study evaluated recovery of copper from sawdust of copper azole(CA),micronized copper azole(MCA), alkaline copper quat(ACQ), and micronized copper quat(MCQ) using three different extraction procedures; toxicity characteristic leaching procedure(TCLP), sonication with heated water, and sonication with room temperature water. Two extraction fluids were used, monoethanolamine (MEA) and acidic water. No significant differences in copper recovery were observed between CA, MCA, MCQ, and ACQ using acidic water in any extraction procedures. Copper recovery was significantly higher for MEA than acidic water for all preservatives. Significantly higher levels of copper were recovered for CA and MCA than ACQ and MCQ with MEA extraction fluid.