Separation during production

Separation during production. In some cases, the gaseous radionuclide product can be Isolated during Its production, l.e., during the bombardment of the target, and thus a "zero time" separation can be realized. The study of 20-second C10 produced by the B10(p,n) reaction (228,229) can be cited as a typical example of such a separation technique. 

Norphlet formation waters produced from three Fairway Field wells were analysed for major components and for selected minor cations as part of normal production operations (Table 1). The samples were taken from platform separators during production. Multiple samples from individual wells taken over a period of several years show only minor variations in composition. The waters are extremely saline brines with total dissolved solids between 300 and 373 g/1. Chlorine is the dominant anion in these brines, and sodium (71.6-89.8 g/1), calcium (33.0-41.6 g/1) and potassium (12.9-17.6 g/1) are the major cations. Norphlet formation waters at Fairway are also characterized by relatively high concentrations of Mg, Ba, Sr, Fe, Mn, Li and Pb. Brines of similar composition are produced from deep Norphlet reservoirs and other Mesozoic strata of onshore Mississippi (Carpenter et al. 1974 Kharaka et al. 1987). 

Equip a 1 Utre three-necked flask or a 1 litre bolt- head flask with a reflux condenser and a mercury-sealed stirrer. Dissolve 50-5 g. of commercial 2 4-dinitro-l-chlorobenzene in 250 ml. of rectified spirit in the flask, add the hydrazine solution, and reflux the mixture with stirring for an hour. Most of the condensation product separates during the first 10 minutes. Cool, filter with suction, and wash with 50 ml. of warm (60°) rectified spirit to remove unchanged dinitrochlorobenzene, and then with 50 ml. of hot water. The resulting 2 4-dinitrophenylhydrazine (30 g.) melts at 191-192° (decomp.), and is pure enough for most purposes. Distil oflF half the alcohol from the filtrate and thus obtain a less pure second crop (about 12 g.) recrystallise this from n-butyl alcohol (30 ml. per gram). If pure 2 4-dinitrophenylhydrazine is required, recrystallise the total yield from n-butyl alcohol or from dioxan (10 ml. per gram) this melts at 200° (decomp.). 

Other Products. Other products from sugarcane, in addition to cane sugar, are cane fiber (known as bagasse) and molasses, the final thick symp from which no more sugar may be economically removed by crystallization. In some cane-growing countries, cane tops and leaves, separated during harvest, are used for catde feed. 

Reactions of this type can also occur when the conductivity of one of the phases is very low or practically zero. In these reactions, the sites of reactant lattice destruction and product lattice formation are spatially separated. During the reaction, dissolved species diffuse from the dissolution sites to sites where they undergo further reaction and form the nuclei of the new phase. The length of the diffusion pathway in the sofution depends on the degrees of dispersion of the originaf reactant and resufting product, and most often is between 10 and 10 m. 

The filtration equation (5.3-21) must be adopted if a centrifuge is used for separation. During centrifugation, the surface of the filter cake accessible for flow decreases since the cake builds up toward the axis of the centrifuge. Therefore, must be substituted by the product AcAim where is the average flow area and Aim is the logarithmic mean area through the cake. This yields ... 

The initial processing steps are determined to a large extent by the location of the product species, and they generally consist of cell/broth separation and/or cell debris removal. For products retained within the biomass during production, it is first necessary to concentrate the cell suspension before homogenization or chemical treatment to release the product. Clarification to remove the suspended solids is the process goal at this stage. 

Minerals dominated by cadmium are rare the sulfide CdS (greenockite), especially, is very rarely found. However, cadmium is widespread in zinc ores in low concentrations (0.2-0.4%) and is separated during processing of these ores and production of zinc. 

Increased conversion and product purity are not the only benefits of simultaneous separation during the reaction. The chromatographic reactor was also found to be a very suitable tool for studying kinetics and mechanisms of chemical and biochemical reactions. Some recent publications describe the results on investigation of autocatalytic reactions [135], first-order reversible reactions [136], and estimation of enantioselectivity [137,138]. It is beyond the scope of this chapter to discuss the details, but the interested reader is referred to an overview published by Jeng and Langer [139]. 

As shown in Figure 15-2, the two separate amplification products obtained from the primary amplification contain the desired mutation and correspond to one-half of the targeted template. These purified fragments also contain a 24-bp region at each end that is complementary to the other half. During the secondary PGR, equal amounts of each primary PCR product are mixed and only the external primers (numbers 1 and 4) are used. Hybrid structures form between the denatured templates within the region of... 

It has been mentioned earlier that using porous membranes for product separation during the course of an equilibrium reaction, maximum attainable conversions are limited because of reactant permeation. This is the case where the membrane forms the wall of the reactor in which a catalyst is packed. It has also been mentioned that in this mode equilibrium conversions for some slow reactions could be increased by factors ranging between 1.3 and 2.3. Another important operation mode arises when the membrane is inherently catalytic or when the catalytically active species are placed within the membrane pores (catalytically active membrane as shown in Figure 7.2b and 7.2c). In this case, reaction and separation take place simultaneously and are combined in parallel rather than in series as was the case in the previous mode. 

After bromination of 144 g. (1 mole) of 2-naphthol, the hot solution is poured into water and filtered. The dry precipitate is mixed with a solution of 200 ml. of concentrated sulfuric acid in 500 ml. of technical methanol and heated to vigorous reflux for 4 hours. An oily layer separates during the heating period. The hot mixture is poured into 3 1. of ice and water, and the solids are removed by filtration. The moist solid is triturated with 11. of hot 5% sodium hydroxide. After chilling the mixture to solidify the oil, it is filtered and the product is washed and dried. The 6-methoxy-2-bromonaphthalene is purified by distillation, b.p. 114-118° (0.2 mm.). After distillation the product is most conveniently handled by remelting and pouring it into a mold to solidify. The overall yield is 173-208 g. (73-88%), m.p. 101.5-103°. 

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