Carbon dioxide storage under

In dry air the stability of zinc is remarkable. Once the protective layer of zinc oxide formed initially is complete, the attack ceases. Even under under normal urban conditions, such as those in London, zinc sheet 0 -8 mm thick has been found to have an effective life of 40 years or more when used as a roof covering and no repair has been needed except for mechanical damage. The presence of water does, of course, increase the rate of corrosion when water is present the initial corrosion product is zinc hydroxide, which is then converted by the action of carbon dioxide to a basic zinc carbonate, probably of composition similar to ZnCOj 3Zn(OH)2 . In very damp conditions unprotected zinc sometimes forms a loose and more conspicuous form of corrosion product known as wet storage stain or white rust (see p. 4.171). 

Carbon dioxide capture and storage is especially studied in connection with electricity generation, where different technology routes - post-combustion capture, pre-combustion capture and oxyfuel combustion - are under research and development. Carbon dioxide capture is also crucial in connection with hydrogen production... 

The question often arises whether a sample must be analyzed immediately or can be stored, and if so, under what conditions and for how long (B4a, H5a, W9a). Freshly drawn blood maintained anaerobically (A3) at 38 C decreases in pH at the rate of —0.062 unit per hour and in pCOj, at 4.8 1.3 mg Hg per hour. At 0-4°C, the change is minimal — 0.006 0.004 pH unit and 0.6 0.06 mm Hg. There has been controversy concerning the use of minerol oil to maintain specimens for carbon dioxide analysis (G2). Paulsen found that values of total carbon dioxide in plasma collected in stoppered tubes with and without paraflSn oil were identical if the tubes without oil were completely filled to the stopper (P4). The loss of carbon dioxide in tubes stored at room temperature without oil was about 6 mEq/1 in 2.5-4 hours. The problem for the laboratory is unfilled tubes and the storage of separated serum or plasma before analysis and in plastic cups during continuous-flow procedures. 

Filter product into this storage tank. Fill under carbon dioxide cover. 

Since ethyleneamines react with many other chemicals, dedicated processing equipment is usually desirable. Amines slowly absorb water, carbon dioxide, nitrogen oxides, and oxygen from the atmosphere, which may result in the formation of low concentrations of by-products and generally increase color. Storage under an inert atmosphere minimizes this son of degradation. 

Conditioning of the Product. The high porosity and low moisture content of the freeze-dried product require that the vacuum be broken and packaging he done under a dried inert-gas blanket, in many cases, to prevent oxidation during storage and maintain the low moisture content. Carbon dioxide or nitrogen are commonly used. 

A simple and effective form of degassing is to hold a flask of mobile phase under a vacuum while agitating the contents in an ultrasonic bath (Fig. 3.7). The eluent is then transferred to the chromatograph for several hours of reliable operation, especially if the eluent is blanketed with an inert gas such as helium. This approach is particularly useful for clean solvents that readily absorb gases such as carbon dioxide from the atmosphere. The eluent should be degassed in the solvent storage container used for chromatography to minimize contact with the air. 

Store chemicals that react with fire-fighting materials (i.e., water or carbon dioxide) under conditions that minimize the possibility of a reaction if a fire is being fought in the storage area. 

If desired, the methylmagnesium carbonate can be recovered as a white, brittle solid by evaporation of the solution under vacuum at temperatures up to 100°C. Unlike magnesium methoxide, which becomes almost completely insoluble on recovery as a solid, methylmagnesium carbonate solid is very soluble in methanol but tends to dissolve faster if the methanol is presaturated with carbon dioxide. The solid form provides a convenient method of storage or shipment of the material, much like instant coffee. 

THE PRESSURIZED VAT. The idea underlying the pressurized vat is based on a principle similar to the Seitz-Bohi process. Carbon dioxide produced by fermentation is supposed to build up an overpressure which prevents further fermentation in the tank. Pressure-tolerant yeast strains, however, can survive several bars of overpressure and produce much more than 0.5% by volume of alcohol before fermentation stops. Prolonged storage is only possible with clarified juices at low temperatures. 

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