Separators lead acid

Separations based upon differences in the chemical properties of the components. Thus a mixture of toluene and anihne may be separated by extraction with dilute hydrochloric acid the aniline passes into the aqueous layer in the form of the salt, anihne hydrochloride, and may be recovered by neutralisation. Similarly, a mixture of phenol and toluene may be separated by treatment with dilute sodium hydroxide. The above examples are, of comse, simple apphcations of the fact that the various components fah into different solubihty groups (compare Section XI,5). Another example is the separation of a mixture of di-n-butyl ether and chlorobenzene concentrated sulphuric acid dissolves only the w-butyl other and it may be recovered from solution by dilution with water. With some classes of compounds, e.g., unsaturated compounds, concentrated sulphuric acid leads to polymerisation, sulphona-tion, etc., so that the original component cannot be recovered unchanged this solvent, therefore, possesses hmited apphcation. Phenols may be separated from acids (for example, o-cresol from benzoic acid) by a dilute solution of sodium bicarbonate the weakly acidic phenols (and also enols) are not converted into salts by this reagent and may be removed by ether extraction or by other means the acids pass into solution as the sodium salts and may be recovered after acidification. Aldehydes, e.g., benzaldehyde, may be separated from liquid hydrocarbons and other neutral, water-insoluble hquid compounds by shaking with a solution of sodium bisulphite the aldehyde forms a sohd bisulphite compound, which may be filtered off and decomposed with dilute acid or with sodium bicarbonate solution in order to recover the aldehyde. 

Polymers containing 8-hydroxyquinoline appear to be selective adsorbents for tungsten in alkaline brines (95). In the presence of tartrate and citrate, quinaldic acid [93-10-7] allows the separation of zinc from gallium and indium (96). Either of these compounds can selectively separate lead and zinc from oxide ores as complexes (97). It is also possible to separate by extraction micro quantities of rhenium(VII), using quinoline in basic solution (98). The... 

Fig. 2. Cutaway view of a tubular positive lead—acid battery, (1) Positive tubular plate (2) iiegatwe plate (3) separator (4) connecting strap (5) ceU cover (6)...

The lead—acid battery is comprised of three primary components the element, the container, and the electrolyte. The element consists of positive and negative plates connected in parallel and electrically insulating separators between them. The container is the package which holds the electrochemically active ingredients and houses the external connections or terminals of the battery. The electrolyte, which is the Hquid active material and ionic conductor, is an aqueous solution of sulfuric acid. 

The separator must be stmcturaHy sound to withstand the rigors of battery manufacturing, and chemically inert to the lead—acid cell environment. Numerous materials have been used for separators ranging from wood, paper, and mbber to glass and plastic. The majority of separators used are either nonwoven—bound glass or microporous plastic such as PVC or polyethylene. 

A lead-acid battery consists of electrolytic cells, each containing an anode of porous lead, a cathode of primarily lead peroxide (PbO,), and electrodes of metallic lead. The anode and cathode are separated by nonsulfuric acid and water. 

From this — albeit rather rough — overview, the proportions become clear around 45 percent of all battery sales worldwide and thus also separator sales worldwide are in lead-acid batteries and... 

Reprinted from W. Bohnstedt, Automotive lead/acid battery separators a global overview, J. Power Sources, 1996, 59, 45-50, with kind permission from Elsevier Science S.A., Lausanne. 

The historical development of the separator and of the lead-acid storage battery are inseparably tied together. When referring to lead-acid batteries today one primarily thinks of starter batteries or forklift traction batteries, but the original applications were quite different. 

The very first functioning lead-acid battery was presented by Gaston Plante in 1860 spirally would lead sheets served as electrodes, separated by a layer of felt — the first separator of a lead-acid battery [12], This assembly in a cylindrical vessel in 10% sulfuric acid had only a low capacity, which prompted Plante to undertake a variety of experiments resulting in many improvements that are still connected with... 

Electric road vehicles have been reduced to insignificance, as mentioned already by, vehicles with combustion engines. Another electric vehicle — the electrically driven submarine — presented a continuous challenge to lead-acid battery separator development since the 1930s and 1940s. The wood veneers originally used in electric vehicles proved too difficult to handle, especially if tall cells had to be manufactured. Therefore much intense effort took place to develop the first plastic separators. In this respect the microporous hard rubber separator, still available today in a more advanced version, and a micro-porous PVC separator (Porvic I) merit special mention 28]. For the latter a molten blend of PVC, plasticizer and starch was rolled into a flat product. In a lengthy pro-... 

Finally, one development results from returning to a basic idea from the dawn of the lead-acid battery, wherein the functions of support for the positive active material and of the separator are combined into one component the gauntlet separator [84] consisting of a coarsely porous, flexible support structure coated with micropo-rous polyethylene material for separation. The future has to show whether this approach will be able to meet all demands. 

Table 11. Separators for lead-acid traction batteries...

Separators for Valve Regulated Lead-Acid Batteries... 

Table 12. Separators for flooded lead-acid stationary batteries...

Table 13. Separators for valve-regulated lead -acid batteries (liquid electrolyte)...

One version of the microporous, filled polyethylene separator ( PowerSep ) [113], which is so successful in the lead-acid battery, is also being tested in nickel-cadmium batteries. This separator is manu-... 

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