Sodium consumption, factors

These data don t mean that everyone should rush out and start gobbling salt. The patients involved had significant hypertension and other factors to consider. But the findings do cast a big shadow on blanket recommendations that everyone should severely restrict his or her sodium consumption. 

The third aspect of improvement may mean an entirely different process for making an old substance. For many decades soap has been manufactured by caustic soda saponification of fats in the batch process. In recent years plants have been installed for the high pressure, high temperature rapid hydrolysis of fats in the countercurrent liquid mixed phase using water and a catalyst. In this case the sodium fatty acid or the soap may be prepared by neutralizing the free fatty acid hydrolysis product with caustic soda or soda ash depending upon convenience and the market. Naturally the unit consumption factors changed when the improved process was used. 

Alkali sihcates are used as components, rather than reactants, in many appHcations. In many cases they only contribute partially to overall performance. Utility factors are generally not as easy to identify. Their benefit usually depends on the surface and solution chemical properties of the wide range of highly hydrophilic polymeric siUcate ions deUverable from soluble sihcate products or their proprietary modifications. In most cases, however, one or two of the many possible induences of these complex anions cleady express themselves in final product performance at a level sufficient to justify their use (102). Estimates of the 1995 U.S. consumption of sodium sihcates are shown in Table 6. 

In most ores, sufficient Fe is already present. For some ores, it is necessary to add metallic iron. In practice, the oxidation potential of the solution can be monitored and controlled using the Fe /Fe ratio. Very high leaching efficiencies with H2SO ate common, eg, 95—98% dissolution yield of uranium (39). If acid consumption exceeds 68 kg/1 of ore treated, alkaline leaching is preferred. The comparative costs of acid, sodium hydroxide, and sodium carbonate differ widely in different areas and are the determining factor. 

The specific use appHcations of sodium chlorite varies from country to country. Important factors are the regulatory and environmental laws in effect for air and water quaUty standards. Sodium chlorite is generally priced at about four to six times the cost of sodium chlorate. The Hst price of 80% technical-grade NaC102 in January 1991 was 2.65/kg (146). In 1990, the estimated consumption of sodium chlorate for the production of sodium chlorite in Canada was about 2700 metric tons and about 9100 metric tons in the United States (74). In Western Europe, the 1990 chlorate consumption estimate was about 11,000 metric tons. A summary of 1991 U.S. and foreign sodium chlorite producer annual plant capacities in various world market areas is given in Table 3. 

The salt consumption with a sodium 0.275 and 0.533 Lbs of salt per 1,000 grains of hardness, expressed as calcium carbonate, removed. This range is attributed to two factors (1) the water composition, and (2) the operating exchange value at which the exchange resin is to be worked. The lower salt consumption may be attained with waters that are not excessively hard nor high in sodium salts, and where the exchange resin is not worked at its maximum capacity. 

Sears 189) and Heston et al. 190) used the adsorption of sodium hydroxide for the determination of the surface area of colloidal silica. An empirical factor was used for the conversion of alkali consumption into surface area. This is permissible provided the packing density of surface silanols is constant. The determination was performed in concentrated sodium chloride solution in order to keep down the dissolution of silica. Using the same technique, it was found in my laboratory that all surface silanol groups as determined by other methods are neutralized at pH 9.0. At higher pH, siloxane bonds in the surface were opened. A maximum in the sorption of Na+ ions occurred usually at pH 10.5-10.6 which corresponded to a packing density of ca. 5 OH/100 A. On further addition of alkali, silicate ions H3Si04 went into solution. 

The study authors calculated sodium chlorite intakes (in mg/kg/day) from measured water consumption and body weight data. These intakes were multiplied by a factor of 0.75 to adjust for the fraction of chlorite in sodium chlorite, resulting in calculated doses of chlorite in units of mg/kg/day. 

Solution Required. A 0.1 N solution is prepared by dissolving 17.1 g of silver nitrate in chloride-free distilled water and diluting to 1 liter in a volumetric flask. The silver nitrate solution is standardized using accurately weighed 0.1-g portions of dried reagent-grade sodium chloride. The factor [F] is calculated from the chloride consumption. The standardized solution is stored in a dark bottle. 

Several elements (Zn, Pb, Cuy Ni, Ca, Mg, Fe, and Mn) are determined routinely in water samples using atomic absorption spectroscopy. Sodium and potassium are determined by flame emission. The preparation of the samples the analytical methody the detection limits and the analytical precisions are presented. The analytical precision is calculated on the basis of a sizable amount of statistical data and exemplifies the effect on the analytical determination of such factors as the hollow cathode sourcey the ffamey and the detection system. The changes in precision and limit of detection with recent developments in sources and burners are discussed. A precision of 3 to 5% standard deviation is attainable with the Hetco total consumption and the Perkin-Elmer laminar flow burners. 

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