Electrolytic separators

Ohmic Drops. Another irreversible contribution to the measured cell voltage is the ohmic or JR drop across the electrolyte, separator, and cell hardware. The JR drop across the hardware can be estimated from Ohm s law and the relationship... 

Separator s a physical barrier between the positive and negative electrodes incorporated into most cell designs to prevent electrical shorting. The separator can be a gelled electrolyte or a microporous plastic film or other porous inert material filled with electrolyte. Separators must be permeable to ions and inert in the battery environment. 

Distillation appHcations can be characterized by the type of materials separated, such as petroleum appHcations, gas separations, electrolyte separations, etc. These appHcations have specific characteristics in terms of the way or the correlations by which the physical properties are deterrnined or estimated the special configurations of the process equipment such as having side strippers, multiple product withdrawals, and internal pump arounds the presence of reactions or two Hquid phases etc. Various distillation programs can model these special characteristics of the appHcations to varying degrees and with more or less accuracy and efficiency. 

When the copper content in the Dorn metal has been reduced to less than 1% by fire refining, the metal is cast into anodes for electrolytic separation of silver. A typical analysis of Dorn metal is... 

Chemical exchange between hydrogen and steam (catalyzed by nickel—chromia, platinum, or supported nickel catalysts) has served as a pre-enrichment step in an electrolytic separation plant (10,70). If the exchange could be operated as a dual-temperature process, it very likely... 

Conventional batteries consist of a liquid electrolyte separating two solid electrodes. In the Na/S battery this is inverted a solid electrolyte separates two liquid electrodes a ceramic tube made from the solid electrolyte sodium /5-alumina (p. 249) separates an inner pool of molten. sodium (mp 98°) from an outer bath of molten sulfur (mp 119°) and allows Na" " ions to pass through. The whole system is sealed and is encased in a stainless steel canister which also serves as the sulfur-electrode current collector. Within the battery, the current is passed by Na+ ions which pass through the solid electrolyte and react with the sulfur. The cell reaction can be written formally as... 

ELECTROLYTIC SEPARATION OF METALS WITH CONTROLLED CATHODE POTENTIAL 12.6... 

Electrolytic separation of metals 508, 509 of cobalt and nickel, (cm) 533 with controlled cathode potential, 517, 518 see also under individual metals Electromagnetic radiation 646 Electron as standard reagent 535 Electron capture detector 242... 

The alkaline version of the Mn02 / zinc cell follows a different concept because it turns the construction of the Leclanche cell completely around now the cathode (Mn02 + carbon) forms a hollow cylinder contacting the inner wall of the cell container (steel) along its outer surface. The inner cavity has to accommodate anode, electrolyte, separator, and current collector. Usually, the separator forms a basket, which is automatically inserted and pre-... 

A special case of interfaces between electrolytes are those involving membranes. A membrane is a thin, ion-conducting interlayer (most often solid but sometimes also a solution in an immiscible electrolyte) separating two similar liquid phases and exhibiting selectivity (Fig. 5.1). Nonselective interlayers, interlayers uniformly permeable for all components, are called diaphragms. Completely selective membranes (i.e., membranes that are permeable for some and impermeable for other substances) are called permselective membranes. 

In each case, the set up consist of two half cells, each containing an electrode dipping into a solution of an appropriate electrolyte, separated by a salt bridge or similar device. Atoms of elements having a greater tendency to lose electrons (Ni, Zn) are oxidized at the anode, giving up electrons which travel through the external circuit to the cathode, where they combine with the cation (Cu2+, H+) which is most readily reduced. An illustrative list of cells with different types of electrode is shown in Table 6.9, while an illustrative list of various types of half-cell is shown in Table 6.10. 

In electrogravimetry, also called electrodeposition, an element, e.g., a metal such as copper, is completely precipitated from its ionic solution on an inert cathode, e.g., platinum gauze, via electrolysis and the amount of precipitate is established gravimetrically in the newer and more selective methods one applies slow electrolysis (without stirring) or rapid electrolysis (with stirring), both procedures either with a controlled potential or with a constant current. Often such a method is preceded by an electrolytic separation using a stirred cathodic mercury pool, by means of which elements such as Fe, Ni, Co, Cu, Zn and Cd are quantitatively taken up from an acidic solution whilst other elements remain in solution. 

Lithium iodide pacemaker batteries use lithum iodide as the electrolyte, separating the lithium anode and the iodine anode. The function of the electrolyte is to transport ions but not electrons. Lithium iodide achieves this by the transport of Li+ ions from the anode to the cathode. This transport is made possible by the presence of Li vacancies that are generated by the intrinsic Schottky defect population present in the solid. Lithium ions jump from vacancy to vacancy during battery operation. 

Beaudry EG, Electrolytic separation technology for treating ionic wastes, slurries and process streams 4th Int. Forum on Electrolysis in the chem Jud, For Lauderdale, FL,. 1990 through (278)... 

The choice of the leading electrolyte for the second stage, in which the micro-constituents were finally separated and quantitatively evaluated, was straightforward, involving a low concentration of the leading constituent (low detection limit) and a low pH of the leading electrolyte (separation according to pK values). 

Consider a system containing two electrolytes separated by a membrane preventing transfer of one kind of ion from one phase into the other, so that this ion is present only in one phase even when the system is in equilibrium. 

In the voltammetry of microparticles, relative quantitations can easily be obtained as follows. Let us first consider a sample containing two electroactive species, A and B. Assuming that under the selected electrochemical conditions (technique, parameters, electrolyte), separated signals are obtained for A and B, the voltanunetric peak currents (or peak areas), IaJe, can be taken as proportional to the number of mols of A and B, xa,Xb, respectively transferred to the electrode. Then, one can write... 

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