Cements silver chloride

A type No. 29 Sauereisen low expansion cement was used for connection of the electrode body and the silver-silver chloride wire. The concentration of the KCl solution in the electrode for this study is 0.1 mol/1. The iron alloy working electrode dimensions were 20mm x 5mm x 1.5mm. The body of the reactor served as the a uciliary electrode. 

For the ion chromatographic analysis of chloride in cement, that cancels out the passivation of steel surfaces in concrete and, thus, is only admitted up to a maximum content of 0.1%, Maurer et al. [93] developed a procedure in which the cement sample is extracted with nitric acid. Since a direct chloride determination is impossible due to the high nitrate concentration in the extract, silver nitrate is added in three-fold excess to the nitric acid extract. The precipitated silver chloride is filtered off and subsequently dissolved in 100 mL of a 0.25% ammonium hydroxide solution. This solution, according to the chloride concentration, can be further diluted with de-ionized water or injected directly. 

In principle these can also be used for ion activity measurement. Life scientists first tried to take advantage of electrodes of the second kind as early as the 1950s. Mauro (36) measured chloride ion concentrations inside the squid giant axon with a micro chloride electrode that he prepared by cementing a 15 gm diameter silver chloride-coated silver wire into the end of a glass capillary. 

Other. Silver chloride, AgCl, has interesting optical properties as it can be made transparent it also is a cement for glass. Silver nitrate, AgNOj, also called lunar caustic, the most important silver compound, is used extensively in photography. 

Although silver is not treated by solvent extraction in any of the flow sheets, silver is recovered from aqueous solution in several other situations. For these processes, Cytec developed reagents with donor sulfur atoms to extract this soft element. For example, tri-isobutylphosphine sulfide (CYANEX 47IX) extracts silver from chloride, nitrate, or sulfate media selectively from copper, lead, and zinc [32]. The silver is recovered from the loaded organic phase by stripping with sodium thiosulfate, and the metal recovered by cementation or electrolysis. Silver can also be extracted from chloride solution by a dithiophosphinic acid (CYANEX 301) [33]. 

Cementation consists in the formation of a surface alloy with a less reactive metal. For zinc, alloying can be effected with mercury (amalgamation), copper, silver, nickel.12 The reactivity of a cemented metal can be explained considering that the supporting metal plays only the role of an electron reservoir, the true chemistry is effected by the superficial additional metal. Zinc can also be activated by washing with aqueous ammonium chloride,13 or by reacting the powder with trimethyl-chlorosilane.14 In this latter case, Barbier reactions were effected even at 0°C in short times. The activation mechanism was not determined. 

Relatively simple methods based on spraying the surface of split cores with silver nitrate have been proposed a colour change indicates the chloride penetration front [48]. The result may depend on the original colour of the concrete and its particular chemistry. More complex tests are based on cutting slices from cores and pressing out the pore solution for determination of the free chloride concentration this techniques was developed for hardened cement paste [49] but is also used for concrete [50]. 

A wide variety of inorganic materials have been used to precipitate or collect trace metals from solution. The most direct approach is a cementation process, which is one that removes the trace pollutants from solution by reduction with a metal and plating onto that metal surface. Although this process may be slow, the filtration is usually quick, since decantation is often sufficient. Finely divided cadmium extracts copper, selenium, and mercury from nitric and sulfuric acid solutions (66). When copper was used to preconcentrate mercury from water or biological fluids prior to atomic absorption analysis, the detection limit was 1-2 X 10 g (67, 68). Iron (69), zinc (70), and tungsten (71), as metals, have also been used to obtain a deposit of several trace metals from aqueous systems as dilute as 10 ppb for subsequent analysis. Elemental tellurium can be produced in solution by reduction using tin(II) chloride or sulfur dioxide, and coprecipitates silver (72) and selenium (73). Granulated silicon-metal alloys were used to remove metal ions from water and brine by reduction as well (74, 75). 

Whichever method is used for preparation, a hot aqueous leach solution is the end point, from which a pure lead chloride must be produced. Cementation with lead powder can be used to separate and recover copper, silver, gold and bismuth as well as removing arsenic and antimony. Separation of lead chloride by crystallisation can then be used, relying on the high temperature dependence of lead... 

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