Sodium, production

Benzoates. The sodium and potassium salts of ben2oic acid [65-85-0], C2H 02, ate most effective against yeast and mold. They ate used in beverages, fmit products, chemically leavened baked goods, and condiments. Owing to their inhibitory effect on yeast, they cannot be used in yeast-leavened products. Potassium ben2oate was developed for use in reduced-sodium products. Ben2oates ate permitted for use in foods up to a level of 0.1% (76). 

Table 8. North American Sodium Production and Uses, t x 10 ...

Salt Substitutes. As a result of concern about the relationship between dietary sodium and hypertension, some salt producers and food companies have developed salt substitutes or low sodium products. Mixtures of sodium chloride and potassium chloride, herbs and spices, as well as modified salt crystals of lower density are marketed in response to a limited consumer demand for reduced-sodium products. This amounts to about 2% of user salt purchases. 

C. N. Swenson and G. Fundale, Observational cohort study of switching warfarin sodium products in a managed care organization, Am J. Health Syst. Pharm, 57, 452 (2000). 

Sodium phosphate(s), 28 831-834, 29 18 carbon dioxide by-product of manufacture, 4 810 economic aspects of, 28 860 uses for, 28 833-834 Sodium polybutadiene, 9 555, 556 Sodium polymetaphosphate, 8 416 Sodium polyphosphates, 9 16 manufacture of, 28 858 Sodium polyphosphate glass, 28 851 Sodium polystyrene sulfonate cosmetic surfactant, 7 835t Sodium polysulfide(s), 23 640 in sodium production, 22 773 Sodium-potassium eutectic, 15 252... 

Sodium potassium tripolyphosphate (SKTP), 28 846 Sodium production, 9 640 Sodium pyrithione... 

Sodium products unrefined sea salt, coarse rock salt, sodium sulfate, sodium carbonate, sodium bicarbonate, sodium chloride... 

The first commercial process for sodium production used the electrolysis of sodium hydroxide, but it had the disadvantage that the current efficiency was less than 50%. At present this process is the only way of producing metallic sodium. The cell reaction is... 

Dunaif, G.D., and C.-S. Khoo. 1986. Developing low and reduced-sodium products An industrial perspective. Food Technol. 40, no. 12 105-107. 

Most people have never seen sodium metal. But it is almost impossible not to see many compounds of sodium every day. Ordinary table salt, baking soda, baking powder, household lye, soaps and detergents, aspirin and other dmgs, and coundess other consumer products are sodium products. 

Occasionally, the market will swing the other way leaving chlorine in short supply. Fused sodium chloride is commercially electrolyzed in Down s cells to give chlorine and metallic sodium [11]. Sodium production in the U.S.A. has averaged 135,000-150,000 metric tonnes annually since 1968, which represents about a 2-3% contribution to the chlorine supply from this source. In the U.K., it is estimated that as much as 10% of the available chlorine arises from Down s cell technology. Potassium chloride solutions are also electrolyzed for commercial potassium hydroxide, but the contribution to the chlorine supply from this source is even less than from fused sodium chloride electrolysis. 

Blouin RA, Clifton GD, Adams MA, et al. Biopharmaceutical comparison of two levothyroxine sodium products. CUn PUarm 1989 8 588-592. 

In addition to the Downs cell for sodium production and the chlor-alkali process for chlorine manufacture, industrial methods based on voltaic and electrolytic cells are used commonly to obtain metals and nonmetals from their ores or to purify them for later use. Here we focus on two key electrochemical processes. 

Energy requirements in electrolytic sodium production h higher than those for magnesium. Heat evolution in reduction h higher than with magnesium, which creates heat dissipation problems... 

Leaching is cheaper than vacuum distillation, which could be applied No excess sodium production capacity is available in U.S. to recycle NaCl or make up for sodium losses... 

The composition of NaCl dissociation products in atmospheric-pressure thermal plasma is shown in Fig. 7-42. The initial concentration of NaCl is 17.1 mol/kg. Sodium formation takes place at temperatures exceeding 3000 K. The energy cost of sodium production from chloride is shown in Fig. 7-43. The minimal energy cost is 9.4eV/atom in the case of absolute quenching, and 8.8 eV/atom in the case of ideal quenching, which can be achieved at a specific energy input of 8.2 eV/mol. 

Figure 7-42. Sodium production by direct decomposition of its chloride (NaCl) in atmospheric-pressure thermal plasma. Composition of products (1) NaCl (2)Cl (3)Na (4)Na+.

Sodium can be produced by high-temperature reaction from almost any its compound (NaCl, NaOH, Na2C03 and Na2S). The method of sodium production that has enjoyed the widest application is electrolysis of the molten salts, for example ... 

Since water interacts with the one-half amount of sodium produced in this reaction, sodium yield cannot exceed 50% of theoretical value. In other electrolysis reactions, the yield of sodium could be even lower. Metallic sodium production by electrolysis of molten NaCl having melting point about 800°C is the most wide spread method. In order to reduce melting temperature such salts as CaCb, Na2COs, etc. are used. For instance, mixture consisting of 40% NaCl and 60% CaCU has melting temperature of 580"C, while mixture of 35.6% NaCl and 64.4% Na2C03 melts at 600°C. 

In electrolytic vat, the anode is usually made of graphite, the cathode being made of metal (Fe). Chlorine being by-product of this process is either discharged into atmosphere or accumulated for further using. Electric energy needed for sodium production is about 15 kW-h/kg Na. 

Sodium produced by electrolysis contains 99.7 to 99.8% of basic metal and impurities (<0.1%K, <0.001% Fe, <0.15% Ca and others, such as Ba, Zr and Sn). It should be noted that the use of graphite electrodes causes sodium to be polluted with carbon. The worldwide sodium production data is given in Table 4.1 [4.1, 4.2]. 

TABLE 4.1. WORLD SODIUM PRODUCTION (thousand tonnes/year)... 

Faced with the risk relating to the discharge into the Rhone which this scenario involves, a fallback scenario for treatment involving caustic soda cementation and long-term storage was chosen (with several possible technical options). The possibility of intermediate storage of all sodium products, which would release the reactor from the monitoring requirements related to... 

The general technology may be illustrated by the example of sodium production in the Down s cell. The electrolyte is a molten mixture of sodium chloride (40%) and calcium chloride (60 wt %) requiring a process temperature of about 600°C. The principle of cell design is shown in Fig. 4.4, although more... 

Other applications of electrolysis that students could research include sodium production by electrowinning (the Downs process) (a useful website on this process is detailed in the Other resources section at the end of the chapter). 

For information about sodium production by electrowinning (the Downs process) ... 

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