Sodium sulfate, precipitation

Sodium sulfate precipitation is not usually recommended for most murine MAbs because mouse/rat IgG can be degraded by the relatively high temperature (25°C) used during this procedure. If lipid contamination of ascitic fluids is a particular problem, add silicone dioxide powder (15 mg/mL), and centrifuge for 20 min at 2000g. Use the method described in Chapter 10, Section 3.2.1. 

The discontinuous or continuous addition of sulfuric acid to sodium chromate solution up to a pH of 3 is technically simple. The resulting solution of sodium dichromate dihydrate is then evaporated to 70% by weight, whereupon almost all the sodium sulfate precipitates out and is separated off. The dichromate solution obtained is in part utilized as such. Further evaporation to ca. 1600 g sodium dichromate/L and cooling to 30 to 40°C leads to crystallization of the dichromate. These processes are either carried out stepwise or continuously. Separation is carried out in a. skimmer or shear centrifuge. 

Despite these trends, solubility behavior can sometimes appear complex, as with sodium sulfate, Na2S04, whose solubility in water increases then decreases (text Fig. 8.22). In this instance, complex solubility behavior arises because different hydrated forms of sodium sulfate precipitate at different temperatures. 

M24. Milne, J., Serum protein fractionation. A comparison of sodium sulfate precipitation and electrophoresis. J. Biol. Chem. 169, 595-599 (1947). 

Hydrazine hydrate (5 g.) is dissolved in 50 ml. of absolute ether, the solution cooled with Ice, and 37.5 ml. of 4N sodium methoxide solution and 12.6 ml. of ethyl nitrite are added. The solution is allowed to stand for a while in the ice and is then slowly warmed to room temperature. The NaNg precipitates and is washed, after suction filtration, with a methanol-ether mixture. If hydrazine hydrate is unavailable, the corresponding quantity of hydrazine sulfate can be used. It is ground with the methoxide solution, and the sodium sulfate precipitated Is filtered off. After the addition of ether, the solution so obtained is reacted with ethyl nitrite. One then proceeds as described above. 

Excessive entrainmentff poor design of deflector/liquid level above the tubes. [Foulingff sodium sulfate precipitates especially in the first effect/lignin precipitates especially in the first and second effect/vapor sulfurization and condensation in third and fourth effects/velocity too small. 

Sodium sulfate decahydrate is a representative material of commercially used latent heat thermal storage media. Sodium sulfate decahydrate has a melting point at 32°C with the latent heat of melting of 60cal/g. It is a grainy crystal below the melting temperature (see Fig. 2 (a)). When sodium sulfate decahydrate melts, it does not dissolve into the separated water at all, because solubility of sodium sulfate to water is negligible. Hence, as shown in Eq. (1), anhydrous sodium sulfate precipitates at the bottom of the liquid and separates into two phases with a saturated aqueous solution of sodium sulfate (see Fig. 2 (b)). 

In addition, there are other methods of manufacture of cryoHte from low fluorine value sources, eg, the effluent gases from phosphate plants or from low grade fluorspar. In the former case, making use of the fluorosiHcic acid, the siHca is separated by precipitation with ammonia, and the ammonium fluoride solution is added to a solution of sodium sulfate and aluminum sulfate at 60—90°C to precipitate cryoHte (26,27) ... 

Sintering has been used to produce a porous polytetrafluoroethylene (16). Cellulose sponges are the most familiar cellular polymers produced by the leaching process (123). Sodium sulfate crystals are dispersed in the viscose symp and subsequently leached out. Polyethylene (124) or poly(vinyl chloride) can also be produced in cellular form by the leaching process. The artificial leather-tike materials used for shoe uppers are rendered porous by extraction of salts (125) or by designing the polymers in such a way that they precipitate as a gel with many holes (126). 

Excess calcium hydroxide is precipitated by usiag carbon dioxide and the calcium carbonate, calcium hydroxide, and calcium phosphite are removed by filtration. The filtered solution is treated with an equivalent amount of sodium sulfate or sodium carbonate to precipitate calcium sulfate or carbonate. Sodium hypophosphite monohydrate [10039-56-2] is recovered upon concentration of the solution. Phosphinic acid is produced from the sodium salt by ion exchange (qv). The acid is sold as a 50 wt %, 30—32 wt %, or 10 wt % solution. The 30—32 wt % solution is sold as USP grade (Table 12) (63). Phosphinic acid and its salts are strong reduciag agents, especially ia alkaline solution (65). 

Processing at Sead.es Lake, California, by North American Chemical is similar to that of Texas brines. Brine is cooled to 16°C to remove borax crystals, then cooled to 4°C which precipitates Glauber s salt. This salt is then separated from its mother Hquor, melted in multi-effect vacuum crystallizers to form anhydrous sodium sulfate, and dried. Both processes produce crystals that are 99.3—99.7% pure (9). 

At Great Salt Lake Minerals Corporation (Utah), solar-evaporated brines are winter-chilled to —3° C in solar ponds. At this low temperature, a relatively pure Glauber s salt precipitates. Ponds are drained and the salt is loaded into tmcks and hauled to a processing plant. At the plant, Glauber s salt is dissolved in hot water. The resulting Hquor is filtered to remove insolubles. The filtrate is then combined with soHd-phase sodium chloride, which precipitates anhydrous sodium sulfate of 99.5—99.7% purity. Great Salt Lake Minerals Corporation discontinued sodium sulfate production in 1993 when it transferred production and sales to North American Chemical Corporation (Trona, California). 

Iron Precipitation. Rich sulfide ore or Hquated antimony sulfide (cmde antimony) is reduced to metal by iron precipitation. This process, consisting essentially of heating molten antimony sulfide ia cmcibles with slightly more than the theoretical amount of fine iron scrap, depends on the abihty of iron to displace antimony from molten antimony sulfide. Sodium sulfate and carbon are added to produce sodium sulfide, or salt is added to form a light fusible matte with iron sulfide and to faciHtate separation of the metal. Because the metal so formed contains considerable iron and some sulfur, a second fusion with some Hquated antimony sulfide and salt foHows for purification. 

Barium sulfate [7727-43-7] BaSO, occurs as colorless rhombic crystals, mp 1580 °C (dec) sp gr 4.50 solubihty 0.000285 g/100 g H2O at 30°C and 0.00118 at 100°C. It is soluble in concentrated sulfuric acid, forming an acid sulfate dilution with water reprecipitates barium sulfate. Precipitated BaSO is known as blanc fixe, prepared from the reaction of aqueous solutions of barium sulfide and sodium sulfate. 

Treatment. Treatment of poisoning from soluble barium salts may be preventive or curative (47,51). Preventive treatment involves inhibition of intestinal absorption by administering such soluble sulfates as magnesium or sodium, causing precipitation of barium sulfate in the alimentary tract. 

Sodium chromate can be converted to the dichromate by a continuous process treating with sulfuric acid, carbon dioxide, or a combination of these two (Fig. 2). Evaporation of the sodium dichromate Hquor causes the precipitation of sodium sulfate and/or sodium bicarbonate, and these compounds are removed before the final sodium dichromate crystallization. The recovered sodium sulfate may be used for other purposes, and the sodium bicarbonate can replace some of the soda ash used for the roasting operation (76). The dichromate mother Hquor may be returned to the evaporators, used to adjust the pH of the leach, or marketed, usually as 69% sodium dichromate solution. 

Purification. Enzyme purity, expressed in terms of the percent active enzyme protein of total protein, is primarily achieved by the strain selection and fermentation method. In some cases, however, removal of nonactive protein by purification is necessary. The key purification method is selective precipitation of the product or impurities by addition of salt, eg, sodium sulfate, or solvent, eg, ethanol or acetone by heat denaturation or by isoelectric precipitation, ie, pH adjustments. Methods have been introduced to produce crystalline enzyme preparations (24). 

A sodium sulfate solution which is not freshly prepared ultimately gives a precipitate of small particle size that is exceedingly difficult and tedious to separate by vacuum filtration. 

The flask is placed in an ice-salt mixture and the contents decomposed by the gradual addition of 300 cc. of saturated ammonium chloride solution and 100 cc. of water (Note 4). The aqueous layer is removed by means of a 1500-cc. separatory funnel and sufficient ether is added to dissolve the yellow precipitate. The total volume of ether solution is about one liter. This is washed with two 200-cc. portions of water, and the three aqueous layers are extracted consecutively with a loo-cc. portion of ether. The combined ether solution is dried over 30 g. of anhydrous sodium sulfate, coricentrated on the steam bath to a volume of about 200 cc., and cooled to room temperature. The product which crystallizes is collected with suction and washed with two 25-cc. portions of ether. The yield is 35-38 g. of light yellow product, m.p. 122-123°. The ether is completely removed from the combined filtrates by heating on the steam bath, and the black oil is allowed to stand overnight. The semi-solid mass is filtered with suction and washed with a minimum amount of cold ether. In this way an additional 6-7 g. of yellow material is obtained which melts at 119-121°. 

Permanent hardness can also be due to the presence of CaS04, in which case the addition of soda (sodium carbonate), NaiC03, produces sodium sulfate, Na2S04, and calcium carbonate, CaCO, this precipitate once again is removed by sedimentation. 

---