Thiagarajan, R. (1988) Effect of beta radiation on the structure of electrical double layer at the mercury-solution interface in presence of organic molecules adsorbed. PhD thesis, Bharathidasan University.

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Theoretical description of the ideally polarized interface is reviewed with particular reference to the structure of the electrical double layer in the presence of adsorbed organic molecules. Various methods of studying the adsorption of organic molecules at the mercury-solution interface have been described and the choice of electro capillary method used in this study is established. Capillary electrometer has been set up and the adsorption of four neutral organic molecules i.e thiourea, benzotriazole, thiosemocarbazide and thiomalic acid has been studied. The charge on the metal surface in the absence and presence of various concentrations of the adsorbate has been evaluated. Surface excess of organic compound adsorbed has also been evaluated using graphical differential. The coverage θ for the organic molecule adsorbed has been evaluated using the equation T/Tm = θ. Surface excess maximum has been evaluated both from the molecular model method and from the initial scope of the C versus C/T curve at qu = θ. Various isotherms for the adsorption of neutral organic molecules at the mercury/solution interface has been tested in the case of organic molecules under study. It is done both by graphical method and by a special computer programme. From the calculated adsorption data it can be shown that the adsorption of thiourea obeys virialisotherm that of benzotriazole obeys Langmuir’s isotherm and the adsorption of thiomalic acid obeys Temkin’s isotherm. The free energy of adsorption in each case is also calculated and the variation of free energy of adsorption with the charge density on the metal surface (qu) is also studied. The effect of beta radiation on the structure of electrical double layer is studied using the beta radiation emitted by P32 in radioactive 0.2N phosphoric acid. In this case also the adsorption of thiourea, benzotriazole, thiomalic acid and thio-semicarbazide at the mercury/0.2n radioactive phosphoric acid solution. Radioactivity present in the base electrolyte is found to enhance the adsorption in the case of thiourea, but the extent of adsorption has been brought down in the case of benzotriazole, thiomalic acid and thiosemicarbazide. It is also found that the adsorption of all the compounds under study obey the same isotherm in both radioactive and non-radioactive base electrolytes. These facts clearly show that the introduction of radioactivity in the base electrolyte will not have any significant effect in the adsorption characteristic except enhancing or decreasing the extent of adsorption. These observations clearly give an additional proof for the experimental fact observed by Kapali and Joshy

Item Type: Thesis (PhD)
Uncontrolled Keywords: Electrical double layer; Mercury-solution interface
Subjects: Electrodics and Electrocatalysis
Depositing User: Dr. N Meyyappan
Date Deposited: 13 Jun 2012 05:07
Last Modified: 13 Jun 2012 05:07

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