Varadharaj, A. (1984) Some contributions to the electrochemistry of gallium-cyclic voltammetric studies in alkali and alkaline gallate solutions. PhD thesis, Madurai-Kamaraj University.

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Electrochemistry of gallium, particularly in alkaline medium is important from the view point of its recovery from Bayer’s liquor-one of the chief sources for gallium. Very few studies are reported in literature coercing the basic aspects of gallium electrochemistry in alkaline medium. Among other reasons, the difficulty of obtaining reliable and reproducible experimental data using gallium working electrodes contributed to a considerable extent to the existence of meagre basic work in this field. In the present work an attempt is made to critical review the available information on the electrochemical behavior of gallium in alkaline medium with a view to highlight the status of the field as it exists and present the various approaches hitherto attempted. This is present in the Chapter-1. Following the presentation of the existing literature, the scope for studies involving a new configuration of the gallium working electrode in the form of Gallium film electrode envisaged in this work has been traced in the same chapter. The introductory Chapter-1 also includes a brief description of the cyclic voltammetry technique and its application in electrode kinetic studies. Methods for the standardization of the gallium film preparation on a suitable substrate material, its evaluation and application in various electrochemical experiments involving both alkali and alkaline gallate media constitute one part of the work. In the other part of the work electrochemical behavior of alkaline gallate at a Hanging Mercury Drop Electrode (HMDE) has been studied and reported. In the subsequent chapters that follow work relating to these two parts has been elaborated. The major experimental technique employed for the polarization studies is cyclic voltammetry – a technique of great importance that is providing to be useful currently in understanding the kinetics and mechanism of the electrode reactions. A wider application of this important technique to the studies involving Gallium has not been done so far. Chapter-II deals with the various experimental aspects of the work such as the details of electrochemical cells employed, the preparation of the solutions used, description of the experimental set up and procedure procedures employed. In Chapter-III experimental results on the optimization of conditions for the electrode position of the gallium film and its characterization to establish its identify through various electrochemical experiments have been described. Chapter-IV deals with the application of the above gallium film in the cyclic voltammetric studies in various concentrations of pure sodium hydroxide and in gallate solutions containing sodium hydroxide. The sweep rate dependence and the alkali concentration dependence of the various features of the cyclic voltammograms – many of which have not been reported earlier and are noticed for the first time in this work are recorded and analysed. Based on these observations an attempt is made to understand the various stages of the anodic oxidation of gallium and the cathodic reduction of gallium under cyclic voltammetric conditions and presented. In the next Chapter-V, the application of the cyclic voltammetric technique has been extended to the studies on HMDE in alkaline gallate solutions that constitute the second part of the work. The objective of this study is to highlight the role of sodium-amalgam in the recovery of gallium metal. The observations obtained from these studies, apart from helping in elucidating the role of sodium in gallium recovery, have resulted in the emergence of a new approach that led to an improved anodic stripping voltammetric technique which holds promise as a simple and sensitive method for analysis at trace levels of various amalgamable metals including gallium. The details of the above observations are presented and discussed

Item Type: Thesis (PhD)
Uncontrolled Keywords: Cyclic voltammetric studies; Alkali; Alkaline gallate solutions
Subjects: Electrodics and Electrocatalysis
Depositing User: Dr. N Meyyappan
Date Deposited: 13 Jun 2012 05:32
Last Modified: 13 Jun 2012 05:32

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