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Title: Adsorption and electrokinetic studies of carbon blacks
Author: Saleeb, Fouad Zaki
Awarding Body: University of London
Current Institution: Imperial College London
Date of Award: 1963
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In the Introduction the importance of zeta-potential in colloidal chemistry is briefly explained. The problem of the small magnitude of the apparent electrokinetic charge density is outlined, and the theoretical treatments of the electrical double layer and of electrokinetic phenomena are summarized. The different systems _used for calculating zeta potentials and the nominal charge density are reviewed and theories proposed for interpreting the results are considered. The object of the present work and method of treatment are formulated. Adsorption of surfactants from aqueous solution on different carbon blacks has been studied primarily to provide an accurate measure of adsorption charge. Surface area relationships, adsorption maxima and the effect of graphitization, ash and tar content of the carbons on these maxima were incidental problems that were examined. Zeta-potentials were calculated from electrophoretic mobilities of the three graphitized carbons of different particle size as a function of surface coverage, using Overbeek's equation. The most reliable results (those subject to small relaxation corrections) were used for calculating diffuse charge densities. The latter were found to be a variable fraction of the adsorption charge. Differentiation between the two main theories for this deviation (namely, enhanced viscosity or Stern's specific adsorption of counterions) was achieved by measurement of negative adsorption of co-ions, an equilibrium property of the double layer which should be independent of viscosity. The combined results are in favour of Stern's structure for the double layer. Different counterions were used to test the theory. Measurements of surface conductance were also made and the results were found consistent with the same theory. Potentiometric titrations of the carbon-oxygen complexes and surface tension measurements for the surfactants used are recorded in Appendices.
Supervisor: Kitchener, J. A. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available