Degassing efficiency

Pressure/RtHng degree proflto Temperature profile Residence time distribution Dlspersion/mixing quality Plastification characteristics Intake characteristics Degassing efficiency... 

The residual content and/or the degassing efficiency is determined in the following working equation ... 

Narrow residence time distribution High dispersive and distributive mixing Very high feeding efficiency Low pumping efficiency Reduced degassing efficiency... 

For calibration, microlitre amounts of a gravimetrically prepared standard solution of DMS in ethanediol are injected via the T-fitting into the helium line (see Fig. 24-1), as a sample of degassed (DMS-free) seawater is loaded into the purge vessel. This procedure provides a matrix-matched calibration and minimizes systematic errors by automatically correcting for degassing efficiency and potential DMS losses within the purge and trap unit. To avoid subsequent DMS release from particulates, the DMS-free seawater should be prepared from a filtered sample, ideally from deep water of low DMS concentration. 

Ladle metallurgy, the treatment of Hquid steel in the ladle, is a field in which several new processes, or new combinations of old processes, continue to be developed (19,20). The objectives often include one or more of the following on a given heat more efficient methods for alloy additions and control of final chemistry improved temperature and composition homogenisation inclusion flotation desulfurization and dephosphorization sulfide and oxide shape control and vacuum degassing, especially for hydrogen and carbon monoxide to make interstitial-free (IF) steels. Electric arcs are normally used to raise the temperature of the Hquid metal (ladle arc furnace). 

Table II shows that, at least for the reactions with quinoline and with 4-methylquinoline (lepidine), nickel-alumina and degassed Raney nickel catalysts are of similar efficiency but better yields have been obtained with degassed Raney nickel, and only this catalyst produces the biaryl from 7-methyIquinoIine.

The benefit of WAC over SAC is the extremely high exchange capacity and lower (almost theoretical) regeneration efficiency. There is some additional cost in capital equipment and higher resin prices, but this is more than compensated for by lower operating costs. Weak acid cation resin capacity is flow-sensitive, so flows must match design criteria. The overall dealk/degasser/BX is the most popular IX process of its kind in the world today, followed by BX/SBA(C1). 

Although Ce(IV) oxidation of carboxylic acids is slow and incomplete under similar reaction conditions , the rate is greatly enhanced on addition of perchloric acid. No kinetics were obtained but product analysis of the oxidations of -butyric, isobutyric, pivalic and acetic acids indicates an identical oxidative decarboxylation to take place. Photochemical decomposition of Ce(IV) carbo-xylates is highly efficient unity) and Cu(ll) diverts the course of reaction in the same way as in the thermal oxidation by Co(IIl). Direct spectroscopic evidence for the intermediate formation of alkyl radicals was obtained by Greatorex and Kemp ° who photoirradiated several Ce(IV) carboxylates in a degassed perchloric acid glass at 77 °K in the cavity of an electron spin resonance spectro-... 

Monomers were mixed in the desired ratios (Table 1) in a round-bottomed flask. The resulting mixtures (5g) were diluted with cyclopentanone (45 g). Azobis(isobutyronit-rile) (AIBN) (0.18 g, 3% w/w with respect to the monomer mixture) was then added. The resulting solution was degassed, put under nitrogen, and placed for 48 h in a thermostated oven preheated at 80 °C. The polymerization solution was concentrated to about half of the original volume and subsequently poured in the fivefold volume of diethylether under efficient stirring. The precipitated solid was filtered off and dried under vacuum to constant weight. Isolated yields were about 80% in all cases. 

Left, Charlie Focht of the Nebraska State Agriculture Laboratory prepares the mobile phase for an atrazine assay. Note that the vacuum flask is positioned in an ultrasonic cleaner bath. Simultaneous vacuum filtration and sonication provide a more efficient means for degassing. Right, Charlie adjusts the flow rate setting on the HPLC pump. 

The problem is solved by prefiltering all mobile phases and samples before beginning the experiment. For mobile phases and large sample volumes, this involves utilizing a vacuum apparatus that draws the liquid through a 0.5-pim filter. Since such filtration involves a vacuum, the mobile phase is automatically degassed as well, so the filtration need not be a separate step. An efficient operation would be to filter a mobile phase with a vacuum apparatus while simultaneously sonicating. See Workplace Scene 13.1. 

Methoxy-2 -methylbiphenyl. o-Tolylboronic acid, 10.0 g (73.6 mmol) (Note 1), 16.8 g (71.8 mmol) of 4-iodoanisole (Note 2), and 200 mL of acetone (Note 3) are combined in a 1-L, three-necked flask equipped with an efficient stirbar, two stoppers, and a reflux condenser attached to a gas-flow adapter with a stopcock. Potassium carbonate, 25.0 g (0.180 mol), is dissolved in 200 mL of water (Note 4) in a separate 250-mL Schlenk flask. In a third flask (25-mL Schlenk flask) 3.30 mg (0.02 mmol, 0.2%) of palladium acetate (Note 5) is dissolved in 10 mL of acetone. All three flasks are then thoroughly degassed by four freeze-pump-thaw cycles. Under an argon back flow, one of the stoppers on the three-necked flask is replaced with a rubber septum, and the carbonate and catalyst solutions are added via cannula to form a biphasic mixture. The top layer turns brown upon addition of the catalyst. The septum is... 

Moore TW. Dissolution testing a fast, efficient procedure for degassing dissolution medium. Dissolution Technol 1998 3(2) 3-5. 

The generation of a paramagnetic species by irradiation of a 10 2 M solution of nitrobenzene in thoroughly degassed tetrahydrofuran at room temperature is efficiently quenched 2V) by 10 i mole l i perfluomaphthalene Et—56.6 kcal mole" ). 

---