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Title: Electrochemical studies of polarisable liquid/liquid interfaces
Author: Stewart, Alan Andrew
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1990
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The interface between two immiscible electrolyte solutions (ITIES) has been investigated for cyclic/linear sweep voltammetry of ion transfer, facilitated ion transfer and electron transfer. Approximate analytical solutions have been derived for the different geometries of liquid/liquid interfaces which are known, i.e. planar spherical/hemispherical, micro-hole and micropipette interfaces, for both reversible and quasi-reversible charge transfer. For planar ITIES the solution is the same as for linear diffusion for electron transfer at a metal/electrolyte interface. For spherical and hemispherical ITIES new solutions have been derived which allow a kinetic analysis to be carried out on cyclic voltammetric results, without the need to use extremely high sweep rates. The solution for a spherical interface is then used to approximate a solution for a micro-hole interface by applying the approximation that microdisc and spherical electrodes are equivalent when the ratio of the radii of the spherical electrode to the microdisc electrode is 2/π. This approximation is also used to evaluate a solution for ion transfers across an interface supported at the tip of a micropipette, where the system is also fully characterised experimentally for voltammetry. Using a similar numerical method as applied to the above problems a solution was evaluated for electron transfer across a planar ITIES for both reversible and quasi-reversible reactions. For all of these approximate solutions the trends found are the same as those seen from experimental results. A method is also presented for the kinetic analysis of 'steady-state' voltammetric waves for facilitated ion transfer across an ITIES supported at the tip of a micropipette. The technique is then used to evaluate the rate of K^+ facilitated by BD18C6 and Li^+ transfer facilitated by both ETH1810 and 2,9-dibutyl-1,10-phenanthroline. The use of liquid/liquid interfaces is also investigated as an assay method for catecholamines. As well as using ion transfer at ITIES as a method to determine catecholamines the use of enzyme coupled reactions, in conjunction with stardard redox electrochemistry or liquid/liquid electrochemistry, is also discussed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available