Degassed water

The de-alkalized and degassed water has a pH of 4-5 and (having just passed through an air-blown tower) is laden with oxygen and extremely corrosive. Normal practice is to dose NaOH into the degasser tower sump, at a level sufficient to approach to desired boiler water pH. If this dosing fails, severe corrosion in the degassed water pump, the softener and the feed system will result. 

Most processes will provide for degassing (decarbonation) by means of a degasser, which provides an up-current of air through a tower filled with polypropylene packing counterflow to meet a cascade of water saturated with carbon dioxide. The degassed water collects in a sump at the base of the tower. After degassing, the C02 content is normally less than 5 ppm. 

Where the alkalinity is reduced to only 1 ppm (as CaC03), the pH level is approximately 5.6 for 10 ppm alkalinity, the pH is approximately 6.6. Because of the acidic nature of the degassed water, it is customary to raise the pH level to perhaps 7.0 to 7.5 using raw water or caustic soda, as appropriate, before proceeding to any further conditioning stages. 

Correction of pH level via caustic soda (after the degasser and before the BX) is standard practice. Because both acid regeneration and caustic pH correction are practiced, it is usual to isolate the plant from the mains by providing a break tank. The full plant therefore tends to be break tank, RW booster pump, acid measuring tank, WAC, degasser, degassed water booster pump, pH correction, and BX. A schematic layout of this type of plant is shown in Figure 9.3a. 

Degassed water under ambient conditions has a relaxation time (T and T2) of about 4 s at 30 °C [11,12], However, air-saturated brines may have a relaxation time of about 2-3 s. Light hydrocarbons are even more sensitive to dissolved oxygen [10], For example, the relaxation time of deoxygenated pentane is 14 s while air-saturated pentane is about 3 s. The correlation for degassed alkanes between the relaxation time (Ti), viscosity (q) and temperature (T) is given by Eq. (3.6.1) [13]. 

An intramolecular version of the Diels-Alder reaction with a diene-carboxylate was used by Williams et al. in the synthetic study of the antibiotic ilicicolin H.91 The interesting aspect of this work is that they found that under aqueous conditions, there is an observed reversal of regioselectivity (Eq. 12.31). In toluene, there is a 75 25 ratio of a/b while in degassed water the ratio of a/b is 40 60. 

NaOH, etc.) is added to the degassed water ( 60 ml) with stirring. After complete dissolution of the caustic, additional water is added to bring the weight of the solution to a total weight of 100 grams. The solution is filtered, and stored in a closed container until use in order to minimize adsorption of C02 from the air. 

Similar spatial distribution of active bubbles has been observed in partially degassed water and in pure water irradiated with pulsed ultrasound [67]. For both the cases, the number of large inactive bubbles is smaller than that in pure water saturated with air under continuous ultrasound, which is similar to the case of a surfactant solution. As a result, enhancement in sonochemical reaction rate (rate of oxidants production) in partially degassed water and in pure water irradiated with pulsed ultrasound has been experimentally observed [70, 71]. With regard to the enhancement by pulsed ultrasound, a residual acoustic field during the pulse-off time is also important [71]. 

All the samples were previously dried under vacuum overnight before starting the measurements. Double distilled and degassed water was used in all the experiments. 

A 100-ml standard apparatus (round-bottomed flask, several inlets for stirrer, reflux condenser, nitrogen flux or vaccum,thermometer, heating bath) is evacuated and filled with nitrogen three times.The following solutions are prepared a) 500 mg of sodium oleate (or sodium dodecyl sulfate) in 16 ml of degassed water b) 125 mg (0.32 mmol)... 

Direct flash excitation (>400 nm) or the triplet-acetone-sensitization of nitrosamide X in degassed water or benzene solutions gives the amidyl radical transient exhibiting lax 335-350 nm. This transient is not observed with undegassed solution of X, indicating that oxygen has intercepted the precursor of the amidyl radical at least, with the diffusion controlled rate... 

Eluent degassing is important due to trap in the check valve causing the prime loose of pump. Eoss of prime results in erratic eluent flow or no flow at all. Sometimes only one pump head will lose its prime and the pressure will fluctuate in rhythm with the pump stroke. Another reason for removing dissolved air from the eluent is because air can get result in changes in the effective concentration of the eluent. Carbon dioxide from air dissolved in water forms of carbonic add. Carbonic add can change the effective concentration of a basic eluent including solutions of sodium hydroxide, bicarbonate and carbonate. Usually degassed water is used to prepare eluents and efforts should be made... 

At room temperature, sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaBArp, 227 mg) was added to the reaction mixture followed after 1 min by degassed water (3 mL). The biphasic system was vigorously stirred for 30 min. 

Helium-3 is a decay product of radioactive tritium (3H, half-life = 12.44 years) that has been produced by nuclear bombs as well as naturally by cosmic rays in the upper atmosphere. Because virtually all 3He atoms escape from the surface ocean to the atmosphere, the 3He/tritium ratio in subsurface seawater samples indicates the time since the water s last exposure to the atmosphere. Both 3He and tritium are measured by gas mass spectrometry. Alternatively, tritium may be measured by gas counting with a detection limit of 0.05 to 0.08 tritium unit, where 1 tritium unit represents a 3H/H ratio of lxl0 18. A degassed water sample is sealed and stored for several months to allow the decay product 3He to accumulate in the container. The amount of 3He is then measured by mass spectrometry, yielding a detection limit of 0.001 to 0.003 tritium unit when 400-gram water samples are used. With this technique, the time since a water mass left the surface can be determined within a range from several months to 30 years. 

Caputi et al. (29) conducted a collaborative study for the determination of glycerol in wine and grape juice. This method uses a strong cation-exchange type of column (H form), degassed water as the mobile phase, and an RI detector. The glycerol was determined on samples simply after filtration (0.45 gm) and with an external standard. For wines, the authors obtained a repeatability of 1.25% and a reproducibility of 2.79% (Reprinted from Ref. 1, p. 566, by courtesy of Marcel Dekker Inc.). 

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