Krishnamoorthy, P.V. (1986) Studies on the individual and co adsorption of organic molecules at the mercury/solution interface. PhD thesis, Madurai-Kamaraj University.
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Theoretical descriptions of the ideally polarisable interface are reviewed with particular reference to the structure of the electrical double layer in the presence of adsorbed organic molecules. Various methods for studying the adsorption of organic molecules at the mercury-solution interface have been discussed and the choice of electro capillary method for this study is thus established. Capillary electrometer has been set up and the adsorption of benzoic acid and its five substituted derivatives has been studied. Co-adsorption of hydroxyl benzoic acid and other substituted benzoic acids has also been examined, with a view to study the influence of one organic compound on the adsorption of the other and vice-versa. Charge on the metal surface in the absence and presence of various concentrations of the adsorbate added and surface excess of organic compound adsorbed have also been evaluated using thermodynamics both for the individual as well as for the mixed systems. Various adsorption isotherms for the adsorption of neutral organic molecules at the mercury/solution interface have been tested and fitted in both graphically and by making use of a computer programme specially compiled for the same. From the calculated adsorption data, it is shown that the adsorption of benzoic acid and its substituted derivatives obeys Temkin isotherm, irrespective of the nature and types of substituent present in the benzene ring. Quantitative theories concerning the effect of electric field on the adsorption are discussed, laying stress on the field dependent orientation of the solvent at the metal solution interface and models for water at the interface. Various statistical mechanical models for studying adsorption of organic molecules, the concept of electro sorption valency and the congruence hypothesis in studying isotherms have also been dealt with. The validity of the equation proposed by Devanathan and Tilak for the evaluation of theoretical electrostatic free energy of adsorption has been tested, by comparing the experimental curve for the variation of electrostatic free energy of adsorption with qm, the surface charge, with the theoretically calculated curve. Some agreement is noted only in the case of ortho-methyl benzoic acid. In the case of all other substituted benzoic acids marked deviations are observed both on the anodic and cathodic side of the electro capillary maximum at high field strengths. Finally the mixed adsorption of hydroxyl-benzoic acid with other substituted benzoic acids has been studied and the results are analysed on the basis of the observations reported by Joshi and co-workers
| Item Type: | Thesis (PhD) |
|---|---|
| Uncontrolled Keywords: | Coadsorption of organic molecules |
| Subjects: | Electrodics and Electrocatalysis |
| Divisions: | UNSPECIFIED |
| Depositing User: | Dr. N Meyyappan |
| Date Deposited: | 13 Jun 2012 05:02 |
| Last Modified: | 13 Jun 2012 05:02 |
| URI: | http://cecri.csircentral.net/id/eprint/2821 |
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