Electrogravimetry application

Laboratory apparatus represents an important application sector. Platinum crucibles, dishes, boats and electrodes for electrogravimetry have long been basic items in chemical laboratories. Today the more dimensionally stable alloys Pt97-Ir3, Pt95-Au5, Pt99.7-Ir0.3 are mainly used. Platinum components are essential in fluorine chemistry. 

Some Applications of Electrogravimetry without Potential Control ... 

Some metals determined by electrogravimetric methods and their deposition potentials are given in Table 11.3.1. Detailed discussions of the methods and applications of electrogravimetric methods are available (1, 3, 19, 20). Electrogravimetry can also be carried out with the quartz crystal microbalance as described in Section 17.5. 

C. Gabrielli, J.J. Garcia-Jareno, M. Keddam, H. Perrot, and F. Vicente, Ac-electrogravimetry study of electroactive thin films. II. Application to polypyrrole. J. Phys. Chem. B, 106, 3192... 

Electrodeposition of metals from solution is a well-established technology. The classical electrogravimetry technique uses the increase in electrode mass associated with exhaustive deposition to provide the quantity of metal species initially present in the solution. Recently, the term has been applied to a technique in which a quartz crystal resonator is used as a gravimetric probe although not generally coupled with exhaustive deposition, this approach exploits the same processes and has the advantage of in situ applicability. In either case, control of conditions can facilitate selective deposition of individual elemental metals from mixtures. The technique can also be used via electrodeposition of compounds of known stoichiometry, notably oxides and halides. This article describes the principles involved, strategies for separation of mixtures, and experimental aspects of the technique. 

A common example of application of electrogravimetry is the determination of copper. Copper is reduced at potentials more positive than the reduction of hydrogen ion, so it can readily be deposited on a platinum cathode from acidic solutions (see above). 

See also. Amperometry. Conductimetry and Oscillometry. Coulometry. Electrogravimetry. Ion-Selective Electrodes Oven/iew Glass Solid-State Liquid Membrane Gas Sensing Probes Water Applications. pH. Polarography Overview. Process Analysis Sensors. Sensors Overview Amperometric Oxygen Sensors. Sulfur. Voltammetry Overview Anodic Stripping. Water Analysis Industrial Effluents. 

Electrochemistry, in general, is a technique that lends itself to be combined with other techniques. One such technique is gravimetry. Electrogravimetry, discussed earlier in the chapter, is a technique that relies upon the application of a current or potential to deposit an electroactive species onto an electrode. After the material is deposited, its mass is determined analytically. A quartz crystal microbalance (QCM) is an instrument that monitors mass changes in real time. 

Typical applications of bulk electrolysis include the determination of n or of the total amount of species present (e.g. by electrogravimetry), small-scale preparative electrosynthesis and electroseparation. In addition, any deviation in the linearity of ln(/(0) vs. t or Q t) vs. i(f) indicates complexity in the reaction mechanism (e.g. coupled reactions). 

Finally, application of other methods of analysis can be recommended. Many of the previous electrochemical studies devoted to conducting polymers were carried out in combination with radiotracer technique, AC electrogravimetry, quartz-crystal microbalance, surface plasmon resonance, and even ellipsometry, and atomic-force microscopy. In this context application of emerging experimental techniques such as local EIS and nonlinear impedance analysis may also be recommended. 

Some examples of the applications of AC electrogravimetry to the study of the redox switching of inorganic and organic films are now reported. First, details about Prussian blue, where mainly cation movement can be detected, will be given. Then, the behaviom of PPY, where cations, anions and solvent participate in the charge compensation process, will be described. Finally, a system of sandwiched polymers will be analysed. 

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