| dc.description.abstract | The results presented in this thesis show that electrochemical analysis have been
successfully carried out on raw plant material of Adansonia digitata fruit. All the four
components of the A. digitata fruit, i.e. the greenish hairy outer covering, the woody
covering, the inner white pulp and the seed have redox active moieties and gave clearly
defined cyclic voltammetric responses when studied using bare carbon working
electrode. They all displayed oxidation/reduction peaks at various potentials.
The results show that both hydrochloric and sulphuric acid electrolyte media are
suitable for the analysis of A. digitata fruit components. High electrodeposition rates and
redox efficiencies revealed the significant role of the proton to the redox process. This
was also confirmed by the poor response obtained in the non-aqueous media containing
Scan rate dependence studies showed that the processes were diffusion controlled
on bare carbon working electrode but in the case of modified electrodes, there were cases
of surface attached species. The processes in the white inner pulp and the seed were
shown to be one proton, one electron, processes from the pH dependence studies.
Modification of the working electrode with a conducting polymer, polyaniline,
and clay montmorillonite gave cyclic voltammetric responses with very well defined
peaks. The modified electrodes yielded enhanced peaks with potentials shifted negatively
suggesting there was electrocatalysis. The largest shifts were observed in the inner pulp ..
and the seed parts of the fruit. The response from the clay-modified electrodes on the
other hand, for all the fruit components showed larger shifts as compared to those of
polyaniline modified electrodes. | en |
