Browsing by Author "Alemu, Hailemichael"

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    Electrochemical Investigations of Thermodynamic and Structural Aspects of the Interface Between Two Immiscible Electrolyte Solutions
    (Addis Ababa Universty, 1991-02) Alemu, Hailemichael; Solomon, Theodros (PhD)
    Simple ion transfer across the immiscible water/o-nitrotoluene, water/benzonitrile and water/o-dlchlorobenzene interfaces has been studied using ac and dc cyclic vol\ammetry. The standard Gibbs energies of transfer from water to the organic solvents for several ions have been determ ined. The results are compared with theoretical values calculated using the model of ionic solvation. The transfer across the imm iscible water / nitrobenzene interface of transition metal (Fe, Co, Ni, Cu and Zn) - terpyridine complexes has been studied using ac and dc cyclic voltammetry, linear sweep voltammetry and absorption spectroscopy. From the voltammetric measurements and convolution integral analysis , thermodynamic and transport properties have been evaluated. The transfer behaviour of cuprous ion across the water/l ,2-dlchloroethane interface facilitated by 2,2' -biquinoline has been studied and the mechanisms for the transfer process are proposed. The structure of the electrical double layer at the water /o-nitrotoluene and water/a-dichlorobenzene interfaces containing different base electrolytes with different concentrations has been studied by impedance measurements. The capacitance values obtained from experiments have been compared with the values calculated from the Gouy- Chapman theory. AnalysiS of the results has Indicated the absence of speCific adsorption at the water /0- nltrotoluene in terf ace.
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    Studies of Ion Transfer Across Iamiscible Electrolyte Solutions
    (Addis Ababa Universty, 1983-06) Alemu, Hailemichael; Theedres Salamon
    The transfer of ions across the \water/acetophenone interface has been investigated by ac cyclic voltammetry. The reversibility of the ion transfer at low sweep rates, as well as precise half-wave potential values have been determined from the observed ac cyclic voltammograms. The reversibility of the ion transfer across the water/ acetophenone interface at 10Vi sweep rates has also been further eetablished by using the dc cyclic voltammetric technique. Values of standard Gibbs energies of transfer from water to acetophenone for several ions have been evaluated. These have been compared with theoretically calculated values for this system. Such studies of ion transfer have been extended for the Vlater/nitrobenzene and water/chlorobenzene-nitrobenzene mixture systems using dc cyclic voltammetry. The values of the standard Gibbs energies of transfer for many ions obtained in these systems have been compared with theoretically estimated values. The present experimental results for the water/nitrobenzene system are in very good agreement with those calculated from partition (extraction) experiments by other workers. Attempts have also been made to correlate standard Gibbs energies of transfer with the dielectric constants of the organic mixtures.