Oxygen with sodium

Fig.4 Energy levels for Cr at the (001) surface of the austenitic stainless steels exposed to liquid sodium with oxygen impurities.

If any component of the primary sodium circuit is to be removed from the reactor for the purpose of repair/maintenance, sodium sticking to the surface must be removed because of (a) chemical reaction of sodium with oxygen and moisture in air, and (b) radioactivity of sodium. The process of radioactive sodium removal has been selected for the reasons of safety, effective cleaning of different components, economics, etc. 

Evidence for the solvated electron e (aq) can be obtained reaction of sodium vapour with ice in the complete absence of air at 273 K gives a blue colour (cf. the reaction of sodium with liquid ammonia, p. 126). Magnesium, zinc and iron react with steam at elevated temperatures to yield hydrogen, and a few metals, in the presence of air, form a surface layer of oxide or hydroxide, for example iron, lead and aluminium. These reactions are more fully considered under the respective metals. Water is not easily oxidised but fluorine and chlorine are both capable of liberating oxygen ... 

Salts are formed as with oxygen-containing compounds. For example, C2H5 — S—Na is named either sodium ethanethiolate or sodium ethyl sulfide. If mercapto- has been used as a prefix, the salt is named by use of the prefix sulfido- for —S . 

In the first step cumene is oxidized to cumene hydroperoxide with atmospheric air or air enriched with oxygen ia one or a series of oxidizers. The temperature is generally between 80 and 130°C and pressure and promoters, such as sodium hydroxide, may be used (17). A typical process iavolves the use of three or four oxidation reactors ia series. Feed to the first reactor is fresh cumene and cumene recycled from the concentrator and other reactors. Each reactor is partitioned. At the bottom there may be a layer of fresh 2—3% sodium hydroxide if a promoter (stabilizer) is used. Cumene enters the side of the reactor, overflows the partition to the other side, and then goes on to the next reactor. The air (oxygen) is bubbled ia at the bottom and leaves at the top of each reactor. 

Oxygen scavengers other than hydrazine are also used, especially catalyzed sodium sulfite, which reacts rapidly with oxygen even at room temperatures to form sodium sulfate. Catalyzed hydrazine formulations are now commercially available that react with oxygen at ambient temperatures at rates comparable to catalyzed sulfite (189). At elevated temperatures, the reaction rates are all similar. Table 14 Hsts the standard hydrazine solution products offered by Olin Corp. for sale to the water-treatment market. Other concentrations are available and other companies offer similar products. 

The aromatic rings of kraft lignins can be sulfonated to varying degrees with sodium sulfite at high temperatures (150—200°C) or sulfomethylated with formaldehyde and sulfite at low temperatures (<100° C). Oxidative sulfonation with oxygen and sulfite is also possible. 

A number of chemiluminescent reactions may proceed through unstable dioxetane intermediates (12,43). For example, the classical chemiluminescent reactions of lophine [484-47-9] (18), lucigenin [2315-97-7] (20), and transannular peroxide decomposition. Classical chemiluminescence from lophine (18), where R = CgH, is derived from its reaction with oxygen in aqueous alkaline dimethyl sulfoxide or by reaction with hydrogen peroxide and a cooxidant such as sodium hypochlorite or potassium ferricyanide (44). The hydroperoxide (19) has been isolated and independentiy emits light in basic ethanol (45). 

A high yield chemical pulp, eg, 52—53% bleached yield from softwoods, can be obtained, but strength properties ate inferior to those obtained from the kraft process. If a protector, eg, potassium iodide, is added, an additional 2—3% yield is obtained, as is an improvement in all strength properties. The gas penetration problem can be minimized if ftbetization is accompHshed before treatment with oxygen. Oxygen treatment of virtually all types of semichemical and mechanical pulps has been explored (55). Caustic, sodium bicarbonate, and sodium carbonate have been used as the source of base (56,57). In all cases, the replacement of the kraft by these other processes has not been justified over the alternative of pollution abatement procedures. 

The concentration dependence of iron corrosion in potassium chloride [7447-40-7] sodium chloride [7647-14-5] and lithium chloride [7447-44-8] solutions is shown in Figure 5 (21). In all three cases there is a maximum in corrosion rate. For NaCl this maximum is at approximately 0.5 Ai (about 3 wt %). Oxygen solubiUty decreases with increasing salt concentration, thus the lower corrosion rate at higher salt concentrations. The initial iacrease in the iron corrosion rate is related to the action of the chloride ion in concert with oxygen. The corrosion rate of iron reaches a maximum at ca 70°C. As for salt concentration, the increased rate of chemical reaction achieved with increased temperature is balanced by a decrease in oxygen solubiUty. 

Fig. 2.30. SAM map offractured SiC after sintering with B addition [2.167], (a)-(d) elemental maps in boron, potassium, sodium, and oxygen, respectively. (E), (F) point analyses at points A and B, respectively.

It is available commercially from several routes including as a product from the manufacture of sodium nitrate from sodium chloride and nitric acid, and from a process involving the passage of ammonia and air over heated platinum and treating the nitric oxide so formed with oxygen. 

By removing oxygen completely, corrosion by this gas is eliminated. It can be achieved by the addition of sodium sulfite or hydrazine, which reacts with oxygen. The reaction product will not normally cause any problems. 

It is appropriate to consider first the crevice corrosion of mild steel in oxygenated neutral sodium chloride, and then to consider systems in which the metal is readily passivated. Initially, the whole surface will be in contact with a solution containing oxygen so that attack, with oxygen reduction providing the cathodic process, occurs on both the freely exposed surface and the surface within the crevice (Fig. 1.50). However, whereas the freely exposed surface will be accessible to dissolved oxygen by convection and diffusion, access of oxygen to the solution within the crevice can occur only... 

In some metal components it is possible to form oxides and carbides, and in others, especially those with a relatively wide solid solubility range, to partition the impurity between the solid and the liquid metal to provide an equilibrium distribution of impurities around the circuit. Typical examples of how thermodynamic affinities affect corrosion processes are seen in the way oxygen affects the corrosion behaviour of stainless steels in sodium and lithium environments. In sodium systems oxygen has a pronounced effect on corrosion behaviour whereas in liquid lithium it appears to have less of an effect compared with other impurities such as C and Nj. According to Casteels Li can also penetrate the surface of steels, react with interstitials to form low density compounds which then deform the surface by bulging. For further details see non-metal transfer. 

Write balanced equations for the reaction of (a) sodium with hydrogen. (b) barium with oxygen. 

In outline the procedure consists of carefully weighing about 5-10 mg of sample on to a shaped piece of paper (Fig. 3.11c) which is folded in such a way that the tail (wick) is free. This is then placed in a platinum basket or carrier suspended from the ground-glass stopper of a 500 mL or 1 litre flask. The flask, containing a few millilitres of absorbing solution (e.g. aqueous sodium hydroxide), is filled with oxygen and then sealed with the stopper with the platinum basket attached. 

Prepare a buffer solution (pH 4.5) by dissolving 6 g acetic (ethanoic) acid and 13,6 g sodium acetate in 1 L of distilled water. Pipette 10 mL of a commercial sample of citrus fruit juice into a 1 L graduated flask and make up to the mark with oxygen-free water,... 

Treatment of the bis-ylide generated from bis 2-[(triphenylphosphonio)methyl]phenyl ether and sodium amide with oxygen gives dibenz[A./]oxepin (3) in 50% yield.98 99... 

Furoic Acid (Coll. Vol. r, 270) Furfural is oxidized with oxygen in the presence of an activator, consisting mainly of silver, in dilute sodium hydroxide solutions. U. S. pat. 2,041,184 [C. A. 30, 4515 (1936)]. 

Sulfite reacts readily with oxygen, particularly under hot, alkaline conditions, but the reaction rate is slow in colder, neutral waters thus complete FW deaeration cannot be guaranteed. Consequently, it is standard practice to add a small amount of catalyst to the sulfite. The catalyst is usually cobalt sulfate [more properly, cobaltous sulfate (CoS04) supplied as an anhydrous, monohydrate, or heptahydrate salt] or sometimes cobaltous nitrate. The catalyst is added to 100% sodium sulfite at a concentration level of 0.2 to 0.25%. 

The stoichiometric relationship for 100% sodium sulfite with oxygen (02) is 7.88 1.0 in practice, 10 1 is commonly used... 

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