Showing papers on "Sodium sulfate published in 1988"

Molten‐Salt Corrosion of Silicon Nitride: II, Sodium Sulfate

Abstract: The corrosion mechanism of Si3N4+ Na2SO4/O2 at 1000°C was investigated. Corrosion of both pure and additive-containing Si3N4 was studied. The reaction of Si3N4+ Na2SO4 consists of an initial period of slow weight loss due to Na2SO4 vaporization and oxidation-dissolution. This initial period was the same for all forms of Si3N4. A second region consisted of further oxidation or near termination of reaction, depending on the additive in the Si3N4. A 5- to 10-μm yttrium depletion zone was found after corrosion for the Si3N4 with yttria additives. For comparison, Si and SiC were corroded under similar conditions. These materials corroded substantially faster than all forms of Si3N4.

Molten-salt corrosion of silicon nitride. I - Sodium carbonate. II - Sodium sulfate

Abstract: An experimental study of the corrosion of Si3N4 under thin films of Na2CO3 at 1000 C has been conducted using both pure Si3N4 and Si3N4 with various additives. The reaction mechanism is shown to consist of: (1) the decomposition of Na2CO3 and the formation of Na2SiO3; (2) rapid oxidation; and (3) the formation of a protective silica layer below the silicate. In the second part, the corrosion mechanism of Si3N4 + Na2SO4/O2 at 1000 C was studied for both pure and additive-containing Si3N4. The reaction of Si3N4 + Na2SO4 was found to involve an initial period of slow weight loss (due to Na2SO4 vaporization and oxidation-dissolution) followed by further oxidation or the near termination of the reaction, depending on the Si3N4 additive.

Stabilization of biological and pharmaceutical products during thermal inactivation of viral and bacterial contaminants

Abstract: A method of inactivating pathogens in proteinaceous biological and pharmaceutical products which comprises: mixing the product in an aqueous solution with one or more primary stabilizers selected from the group consisting of sugars and sugar alcohols and one or more secondary stabilizers selected from the group consisting of sodium acetate, potassium acetate, lithium acetate, magnesium acetate, ammonium acetate, barium acetate, sodium sulfate, ammonium sulfate, lithium sulfate, potassium sulfate and magnesium sulfate; and subjecting said aqueous solution to a pathogen inactivating process.

Passivation of Iron in Sulfate, Perchlorate, and Borate Solutions: Role of Borate in the Passivation Process

Abstract: The anodic passivation of Fe has been investigated in borate buffer, sulfate, and perchlorate solutions. In sulfate and perchlorate solutions of either pH 3.0 or 8.4, the passivation process is highly inefficient with very large amounts of anodic charge passing before a substantial decrease in current is observed. In these solutions, passivation appears to be associated with precipitation of a salt film and/or changes in the solution pH near the surface which permits the formation of a passive oxide. The efficiency for potential‐step passivation cannot be significantly increased by changing the concentration of the supporting electrolyte, the pH of the solution from 3.0 to 8.4, or the potential of anodization. However, the addition of <5% pH 8.4 borate buffer to the neutral sulfate or perchlorate solutions results in a dramatic increase in the efficiency, with the anodic passiyation charge decreasing by as much as two orders of magnitude. Similar trends are observed in pH 8.4 solutions with previously passivated Fe electrodes which were cathodically reduced to different extents prior to anodization. The more of the prior film that remains on the surface before the anodic potential step in sulfate, the more efficient is the passivation process. The marked similarity of these results suggests that the beneficial action of borate towards Fe passivation is due to its ability to assist in the formation of the surface oxide film. While the pH buffering capacity of the borate can be playing a role, it is possible that borate buffer contains strongly interacting anions which give it an inhibiting capability. The interaction of these anions with the Fe surface is believed to stimulate formation of a surface oxide film, and this could explain the results in the present work. Passivation of Fe in sulfate and perchlorate solutions would be inefficient because these anions, unlike those derived from borate, do not have inhibitive abilities, nor do their solutions have buffering capacity. The results indicate the important role played by prior oxide films, and the need for well‐defined starting surface conditions in passivation experiments.

Fire extinguishing compositions and methods

Abstract: Fire extinguishing compositions which contain sodium chloride, magnesium chloride, sodium sulfate, calcium chloride, magnesium sulfate, and water. Optional constituents are calcium sulfate, potassium sulfate, magnesium bromide, and potassium chloride.

Simple, specific analysis of organophosphorus and carbamate pesticides in sediments using column extraction and gas chromatography

Abstract: A simple, specific procedure was developed for the analysis of organophosphorus and carbamate pesticides in sediment. The wet soil was mixed with anhydrous sodium sulfate to bind water and the residues were column extracted in acetonermethylene chloride (1:1, v/v). Coextracted water was removed by additional sodium sulfate packed below the sample mixture. The eluate was concentrated and analyzed directly by capillary gas chromatography using phosphorus and nitrogen specific detectors. Recoveries averaged 93% for sediments extracted shortly after spiking, but decreased significantly as the samples aged.

Effect of sodium on deposition in a simulated combustion gas turbine environment

Abstract: The effect of gas phase alkali concentration on the adhesion properties of micronized coal has been studied using a laboratory-scale entrained reactor capable of accelerating the combustion products of an injected coal-air mixture to the velocities observed in a combustion gas turbine. Alkali metal sulfates are reputed to act as liquid glue binders which promote inorganic deposit formation under these conditions. In this study, the concentration of alkali was varied by utilizing a series of naturally occurring coals (Arkwright Pittsburgh bituminous, Spring Creek Montana subbituminous, and North Dakota lignite), and by doping Arkwright coal samples with sodium benzoate. Measured sticking coefficients (i.e., the mass fraction of incident ash which sticks to a deposition target) obtained from this series exhibited trends consistent with the glue hypothesis and with the amount of liquid phase sodium sulfate predicted by equilibrium thermodynamic and vapor deposition rate calculations. Thus, between the melting point and dew point of sodium sulfate, higher sodium concentrations in the coal feed resulted in enhanced sticking. Below the sulfate melting point, the sodium concentration had no effect. These measurements provide a confirmation of the glue-like behavior of sodium sulfate in enhancing deposition rates and represent the first successful probing of themore » effect of an individual element upon the properties of fly ash originating from natural and chemically doped fuels under gas turbine combustor temperature and velocity conditions.« less

Determination of Surface Silanols of Silica Gels and HPLC Bonded Phases

Abstract: A rapid method determining the surface silanols of silica gels and HPLC bonded phases involves a titration of silica gel with sodium hydroxide, in a medium of any of the following 10% aqueous salts: sodium chloride, sodium nitrate, sodium sulfate, potassium chloride, potassium nitrate and potassium sulfate. The silanols are quantified as m eg/g. It is possible to determine cation exchange capacity of a cation-exchanger due to an acid as an end group and surface silanols separately.

Porous layer silicate/sodium sulfate agglomerate

Abstract: An agglomerate containing sodium sulfate and as layer silicate, a synthetic layer silicate which has a smectite-like crystal phase, increased contents of bound alkali metal and silicate and a distinctly reduced swelling power compared with pure smectites. The agglomerate can take up significant quantities of an additional liquid component in its pores, resulting in a free-flowing agglomerate which outwardly feels dry. This high adsorption capacity may be used, for example, to take up a liquid detergent component which may then be mixed in combination with powder-form or granular detergent components to form a free-flowing detergent composition.

Improved superabsorbent composition and process

Abstract: The present invention provides an acrylate superabsorbent composition having an improved rate of absorbency, low residual acid content, and a low acrylate monomer content. Acrylic acid, an alkali metal salt of carbonic acid, aluminum acetate, sodium sulfate and water are uniformly reacted preferably using microwave radiation as the heat source.

Measurements of tracer diffusion coefficients of sulphate ions in aqueous solutions of ammonium sulphate and sodium sulphate, and of water in aqueous sodium sulphate solutions

Abstract: The tracer diffusion coefficients of SO2–4 in aqueous (NH4)2SO4 and Na2SO4 solutions, and of water in aqueous Na2SO4 solutions, have been determined at 298.15 K over the concentration range 0.1–1.5 mol dm–3 by means of the diaphragm cell method using 35S and 2H as tracers.

Technical Note: Localized Corrosion of Pure and Sulfur-Doped Nickel in Neutral Sodium Sulfate Solution

Abstract: The localized corrosion of pure and sulfur-doped Ni has been investigated in 0.25 M Na2SO4 (pH 6.5), both with and without addition of chloride ions, at 25 C. Addition of more than 500 ppm l− to Na2SO4 solution is found to cause pitting of annealed pure Ni. Auger electron spectroscopy (AES) examination of the fracture surface of nickel previously exposed to SO2 at 800 for 10 min showed that sulfur had penetrated along the grain boundaries by ∼100 µm. Grain boundary sulfur coverage of more than about 0.01 monolayer causes pitting, with induction time and pitting potential independent of increasing sulfur coverage, in 0.25 M Na2SO4 (pH 6.5), both with and without l−. The diffusivity of sulfur along grain boundaries in Ni at 800 is calculated to be ∼4.6×10−10m2/S.

Estimation of activity and osmotic coefficients of strong electrolytes in water at elevated temperatures

Abstract: It was found over a wide concentration and temperature range that differences between osmotic coefficients of a given electrolyte and a standard electrolyte, φ - φst , can be approximated by a linear relation. Sodium chloride, calcium chloride and sodium sulfate were chosen as standard electrolytes for 1:1, 2:1 and 1:2 electrolytes, respectively. Special numerical procedures were developed for the prediction and estimation of activity and osmotic coefficients at elevated temperatures based on data at two temperatures or on data at room temperature only. Reasonable agreement was found between activity coefficients estimated by the present procedure and those correlated by Pitzer's and Meissner's equations.

Study on the Bile Salt Sodium Scymnol Sulfate, from Rhizoprionodon acutus

Abstract: Sodium scymnol sulfate, which is a major component in bile of Rhizoprionodon acutus, was isolated by 3 steps of chromatography to afford 753 mg of the bile salt from 5 gallbladders (65 g), and its structure was determined to be 3α, 7α, 12α, 24, 26-pentahydroxy-5β-cholestan-27-yl sodium sulfate, on the basis of chemical and physical data

Composition for intestine washing solution and intestine washing solution

Abstract: PURPOSE: To obtain an intestine washing solution capable of readily being administered, showing excellent effects without exerting bad influence on electrolytic balance in the body containing a specific water-soluble polymer, Na salt and K salt of organic acid, sodium chloride, potassium chloride and sodium sulfate. CONSTITUTION: The title composition containing 10-150g water-soluble polymer selected from polyethylene glycol, dextran, dextrin, hydroxyethyl starch, polydextrose, gum arabic, pullulan and pectin, 0-12mmol sodium salt of an organic acid (e.g., acetic acid, lactic acid, citric acid or malic acid), 5-60mmol potassium salt of organic acid, 0-12mmol sodium chloride, 7-60mmol potassium chloride and 0-20mmol sodium sulfate (with the proviso that 2-12mEq calculated as potassium ion). The composition is effective for intestine washing for endoscopy of intestinum crassum, examination of double contrast enema with barium, pretreatment of surgical operation of lower digestive organs. COPYRIGHT: (C)1990,JPO&Japio