"The research program described is divided into three segments. In the first part, the morphology and kinetic studies of Cd2+ removal from ZnSO4 solutions using Zn dust as a reducing agent are presented. In the absence of impurities, the morphology of the Cd deposit shows the formation of two-dimensional or leaf-like dendrites capable of interlocking and forming agglomerates or balls. The size and strength of the agglomerates depend on the initial Cd2+ concentration to Zn metal surface area ratio, the rate of Cd 2+ removal, and the reactor geometry. The presence of additives, like Cu2+ and certain proteins, change the morphology of the deposit giving a more sponge-like structure with less agglomeration. In addition to Cu2+, an increase in the cathode surface area by adding steel, copper or aluminum wool are found to enhance the rate of Cd2+ cementation, and the combination of copper and certain proteins leads to synergistic effects in preventing agglomeration and balling tendencies.
In the second part a modification of the tracer technique of Ettel et al. is developed for determining mass transfer coefficients in electrolytes using the rotating disk electrode. The method involves the direct measurement of the limiting current density of a Ag+ tracer ion in copper sulfate electrolyte by cyclic voltammetry techniques. Additional tests are made by co-depositing the tracer with copper to compare the results of the two methods. The use of another tracer ion, Fe3+, is evaluated and the influence of the initial substrate and operating parameters on the results are examined. The new method appears to be particularly useful in making rapid, cursory evaluations of mass transfer conditions in an electrolytic cell.
In the third part of this research, vertical stationary electrodes are used to measure the mass transfer coefficient of the Ag tracer ion in copper sulfate solutions. It is necessary to use the co-deposition procedure, in which both Ag+ and Cu2+ are plated simultaneously, in conjunction with the electrochemical technique. Initially the mass transfer coefficient of the tracer ion is determined electrochemically by measuring its limiting current density. Next, a series of co-depositions at various current densities is performed and the mass transfer coefficient is redetermined by chemically analyzing the deposit. The enhancement in the mass transfer coefficient of the tracer that resulted from the increased natural convection is determined. A general correlation of the data represented by the equation Sh = 0.673(Sc·Gr)1/4, where Sh, Sc, and Gr are the mass transfer Sherwood, Schmidt, and Grashof numbers, is in good agreement with experimental results"--Abstract, pages ii-iii.
O'Keefe, T. J. (Thomas J.)
Poling, Bruce E.
Askeland, Donald R.
James, William Joseph
Clark, George Bromley, 1912-
Materials Science and Engineering
Ph. D. in Metallurgical Engineering
University of Missouri--Rolla
xvii, 120 pages
© 1985 Jose Rolando Sami Cuzmar Del Castillo, All rights reserved.
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Cuzmar, Jose Rolando Sami, "Mass transport considerations in electrometallurgical reactions" (1985). Doctoral Dissertations. 602.
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