Date of Award

Spring 1965

Document Type

Dissertation

Degree Name

Doctor of Engineering Science in Chemical Engineering

Department

Chemical Engineering

First Advisor

C. L. Mantell

Second Advisor

Michael Frederick

Third Advisor

Carl W. Carlson

Fourth Advisor

Joseph Joffe

Fifth Advisor

Avner Shilman

Abstract

The purpose of this investigation was to study the effects of trace metallic impurities, found in manganese electro-winning solutions, on cathode current-potential curves.

This investigation led to the development of a novel analytical tool, emphasizing polarization curves as a means of detecting trace metallic impurities in manganese sulfate electrolytes. The method possesses two distinguishing features: (a) it uses the competing hydrogen evolution reaction as a means of detecting metallic impurities, and (b) it enables one to establish if the electrolyte is sufficiently pure for efficient electrolysis.

Nine metallic impurities were studied, consisting of: nickel, cobalt, silver, copper, zinc, molybdenum, cadmium, magnesium, and sodium. In the first series of runs, the individual effect of each metallic impurity on the standard polarization curve was determined for a range of concentrations. Not all of the impurities affected the polarization curve; i.e. cadmium, magnesium, and sodium had no effect. Nickel, cobalt, silver, copper and zinc significantly affected the standard curve yielding a correlation between transition current and concentration of impurity. Molybdenum had an effect on the polarization curve which could not be correlated.

In the second series of runs, the effects of binary mixtures of impurities were studied to see if the transition current of the mixture could be predicted from knowing the values for the individual constituents. However, it appeared that interactions occurred between impurities which prevented the prediction of the transition current of the mixture by a simple additive law.

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