Powder electrodes, compound construction

For a well constructed compound powder electrode, the potential value is a parameter particularly important for investigations on contacts and absorbents because exist the connection between the potential and the state of the surface, the catalytic and adsorption properties of powders, and also the surface concentration of the substance adsorbed. 

Both substances differ in color, 1 red, 2, yellow and in crystallographic nature. Each is stable in the other range of concentration of hydrogen ions. The aqueous solution of potassium chloride was saturated by both compounds, and by adding either hydrochloric acid (HCl) or an aqueous solution of potassium hydroxide (KOH) we obtained corresponding pH values of the solution. We dipped powder electrodes in solutions prepared in this way—one series with compound 1, the second series with compound 2 (in separate containers). The powder electrodes were specially constructed to facilitate measurement. 

The major sources of dilute, metal ion liquors are identified within the metals production/processing and chemical industries. Problems associated with traditional methods of metal ion removal are highlighted and the developing role of electrochemical techniques is discussed. Electrode and cell reactions are illustrated via typical examples from laboratory and industrial practice. The need to select an appropriate cell design and to control the reaction conditions is emphasised via consideration of the problems caused by secondary reactions. Important design criteria for electrochemical reactors are summarised. Available reactors are classified according to the nature of the product which may be metal flake or powder, a metal deposited onto a disposable substrate, a metal ion concentrate or an insoluble metal compound. The applications for electrochemical techniques in environmental treatment are illustrated by examples which show features of reactor construction and their typical performance. Current trends are summarised and recommendations are made for further work in critical areas. 

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