Excess volatile

Volatile acids, reported as acetic acid, are the most important operational parameter. In a weU-operating digestion process, the value should be <1 g/L (3.8 g/gal). A value >6 g/L (23 g/gal) indicates malfunctioning optimum pH is 6.8—7.2, and a pH <6.8 indicates excessive volatile acid production. Formerly, lime was added to the digester contents if the pH showed an undesirable drop. However, the reduction in pH indicated a change in organism that could not be remedied with lime (2). 

Petroleum coke. In order to eliminate excess volatile matter, petroleum coke is calcined at temperatures of 1475 to 1525 K. This is a sensitive material, and temperature control is difficult to maintain. 

Volatility or readiness with which a substance vaporizes, is an undesirable characteristic for military explosives. Explosives must be no more than slightly volatile at the temperature at which they are loaded or at the highest storage temperature. Excessive volatility often results in the development of pressure within the rounds of ammunition and separation of mixtures into their constituents. Volatility also affects chemical composition of the explosive resulting in the marked reduction in stability leading to an increase in the danger of handling. 

Ethyl acetate is a product of yeasts and a normal component of wine. Its level can be increased by Acetobacter contamination, although most wines showing excess volatile (acetic) acid do not necessarily contain excess ethyl ester initially. It is quite possible to obtain brandy of normal composition and quality by continuous distillation of newly fermented wine containing excess acetic acid, e.g., 0.1%. On the other hand, ethyl acetate can be formed in continuous columns, particularly if the distillation conditions provide for a relatively high ethanol concentration on the feed tray or immediately below. Since acetic acid is weakly yolatile in all mixtures of ethanol and water, it does not appreciably distill upward. Therefore there is no opportunity for acetic acid to combine wtih ethanol in tray liquids normally of high ethanol concentration. 

Several solvent systems have been utilized for epoxide titration. Desirable properties for a solvent in this connexion are 1 that it be easy to purify and store (2) that it be unreactivc towards both tin-epoxide and the epoxide reagent and 3 that it not be excessively volatile, noxious, or toxic. 

Sulfuryl Azide Fluoride. N3S02.F mw 125.09 N 33.60%- liq. Prepn is by reacting Li azide with sulfuryl fluoride in a mixt of dimethylformamide and dimethyl ether at 25° for 19 hrs with stirring. Excess volatiles are then removed at —66° under vac. The reaction flask is then warmed to RT and the azide prod is distld off to a cooled receiver. The authors (Ref 3) report that the azide is believed to be an expl Refs 1) Gmelin, Syst Nr 9, Tell B, Lieferung B (1963), 1562 ff 2) W. Trauble A. Vocker-odt, Uber Hydrazine und Azidosulfonsaure , Ber 47, 938 (1914) CA 8, 2130 (1914)... 

These results suggest that non-Saccharomyces species may contribute significantly to the fermentation of botrytized wines. C. zemplinina seems not to produce excess volatile compounds nor any specific aroma compounds (Toth-Markus et al., 2002). Its main contribution to the chemical composition might be an increase in glycerol content and in the G F ratio. C. zemplinina and C. stellata have proven to be very fructo-philic yeasts (Mills et al., 2002 Magyar and Toth, 2011 Magyar et al., 2008). 

Table 10.4 Estimate of "excess volatiles" (units of 1020 grams). (After Walker, 1977.)...

Figure 10.49. Model calculation simulating changes in ocean composition as primary igneous rock minerals react with a solution containing the proportions of "excess volatiles" shown in Table 10.4. Concentrations of dissolved species are shown relative to 1 kilogram of water, and the extent of reaction is measured by the amount of igneous-rock minerals destroyed. Changes in slopes on diagram are due to formation of sedimentary minerals. (After Lafon and Mackenzie, 1974.)...

In Figure 10.49 a computer calculation is given, simulating the gigantic acid-base titration that led to the formation of the neutralization products of ocean and sediments. The importance of this calculation is that it demonstrates the essence of equation 10.12 as primary igneous rock minerals react with water and acids, the excess volatiles, by reactions like ... 

Since Hoover et al. ( 3) demonstrated that polarized light reflected from the free surface of a pyrolyzing liquid could be used to directly observe mesophase behavior, hot-stage microscopy has become a useful technique for studying the pyrolysis of carbon precursors. Provided that excessive volatilization does not... 

An Ej value of greater than one represents enrichment of element i in the sample as compared to the reference whereas a value less than one means depletion. In order to avoid possible confusion, sample and reference names can be added after j. As shown in Figure 1(a), the average shale composition is very similar to that of the upper continental crust (Ej i = 1.0 0.3). The obvious exceptions are Li, and volatile elements B, C, N, S, Se, Te, Br, I, As, Cd, In, Sb, Hg, and Bi, which are enriched in the shale in comparison to the upper continental crust when aluminum is chosen as the normalizing element (Li, 2000). These excess volatile elements came from the interior of the Earth by magmatic... 

They note (21), "Considerable development work remains before an integrated process could be demonstrated. Questions include materials of construction to withstand the severe corrosion during the calcination step and the reduction step. Methods of trapping the reduced sodium metal need to be devised. It was found that the nitrate level would have to be reduced to an undetermined low level (probably < 10% ) for a safe carbon reduction reaction. Thermal decomposition may have to be supplemented by chemical reduction to achieve this level. Excessive volatility of sodium and cesium compounds was observed during calcination. To this we add that no calculation of the costs of installing and operating such a sodium removal process has been made. 

However, some LAB can be associated with spoilage problems including stuck alcoholic fermentations (Edwards et al., 1999 Huang et al., 1996), production of off-flavors or off-odors (Costello and Henschke, 2002 Drysdale and Fleet, 1989a Sponholz, 1993), excessive volatile acidity (VA) (Drysdale and Fleet, 1989a Huang et al., 1996), synthesis of polysaccharides responsible for ropiness (Manca de Nadra and Strasser de Saad, 1995), or other defects. 

The naphtha/gasoline, kerosine, and higher boiling streams will usually be sharpened to narrower boiling ranges than obtained directly from the crude still by heating with steam in a reboiler to strip (remove by vaporization) the excess volatiles. Alternatively, these streams may be redistilled in small columns to separate each of them into two or three separate sharper fractions. 

The flash point is sometimes to be found in a mineral oil specification, but the value is not usually of much significance and is merely laid down as some assurance against undue Are risk. Typical values will be from 150°C (302°F) upward, depending on viscosity. The closed test (IP 34) is commonly used, and a minimum value of 140°C (284°F) is required for transformer oil to limit Are risk. The stipulation of a suitable flash point also automatically limits the volatility of the oil, and for this reason the loss on heating (IP 46) can be important to restrict excessive volatility. This can be achieved by setting a suitable minimum flash point on the order of 125°C (257°F). 

Eaborn et al. (El) have prepared steroid bromomethyldimethylsilyl ethers and studied their gas chromatographic behavior. The ethers are prepared by mixing equal volumes of a 0.5 M solution (in hexane) of bromomethyl dimethylchlorosilane and a 0.5 M solution (in hexane) of diethylamine. The mixture is centrifuged, and 0.2 ml of supernatant liquid is allowed to react with 20 /ig of steroid for 3 hours. Excess volatile reagents are removed by vacuum desiccation. The dry residue is dissolved in hexane and injected into the gas chromatograph (Pye model 104 fitted with Ni electron-capture detector). The results are shown in Table 4. 

---