Showing papers on "Sodium sulfate published in 1994"

Measurements of chloride depletion and sulfur enrichment in individual sea‐salt particles collected from the remote marine boundary layer

Abstract: Changes in the elemental ratios of Cl/Na and S/Na in sea-salt particles are expected from the atmospheric reactions of sulfuric and nitric acids with these particles. Chloride depletion is expected to occur upon the liberation of HCl to the gas phase, with the particles remaining enriched in sulfate or nitrate. The elemental ratios of Ca/Na, Mg/Na and K/Na should remain constant during this process. Analysis of chloride depletion and sulfur enrichment was obtained for individual sodium-containing particles from the remote marine Pacific atmosphere in both the accumulation mode (0.06 ≤ Dp ≤ 1.0 μm, where Dp is the particle diameter) and the coarse mode (Dp > 1.0 μm) size range. Sodium-containing particles comprised close to 100% of the coarse mode and 11 to 31% of the accumulation mode by number. Aerosols were collected with a low-perssure impactor and examined with a transmission electron microscope (TEM) coupled with an energy-dispersive X ray (EDX) detector. The elemental ratios obtained from the atmospheric particles were determined by comparison with values obtained from laboratory-generated sea-salt, sodium chloride, and sodium sulfate particles of known size and chemical composition, which served as a calibration set. The elemental ratios of Ca/Na, Mg/Na, and K/Na were found to remain fairly constant between individual sea-salt particles of various sizes for more than 85% of the particles examined. Deviations in the ratio of Cl/Na and S/Na from that of reference seawater values were observed most commonly for the submicrometer sea-salt aerosol. The Cl/Na ratio was significantly (Student's t test, 99.9%) lower than that of reference seawater for 89% of the particles examined, while the S/Na ratios were higher for 100% of the particles. The Cl/Na ratio measured in 48% of the coarse sea-salt particles (1.0 < Dp ≤ 2.5 μm) reflected the ratio in bulk seawater, while the remaining particles had statistically lower ratios and qualitatively different morphologies. All but 3% of these coarse particles had enhanced S/Na ratios over that of bulk seawater. Estimates of non-sea-salt (nss) sulfate mass ranged from 216 to 1422 fg for particles of 0.50 μm in diameter to 861 and 5235 fg for particles of 0.80 μm in diameter, corresponding to 74 to 96% of the sea-salt particle mass. These values are compared with the recent measurements of Mouri and Okada [1993] as well as predictions from the atmospheric chemistry models of in-cloud sulfate production of Hegg et al., [1992] and estimations of S(IV) oxidation in sea-salt aerosol water by Chameides and Stelson [1992].

Precipitation of sodium chloride and sodium sulfate in water from sub- to supercritical conditions: 150 to 550 °C, 100 to 300 bar

Abstract: Flow experiments simulating the rapid precipitation of salts during the supercritical water oxidation (SCWO) waste treatment process were performed. Aqueous salt solutions were injected into a coaxially flowing supercritical water stream at a constant pressure of 250 bar. Jet concentrations ranged from 0.1 to 10.0 wt % salt with a typical flow rate of 0.5 g min -1 and temperature of 150 °C. The flow rate of the pure supercritical water stream was typically 10.2 g min -1 with an initial temperature of 550 °C. Results from scanning electron microscopy of collected solids, in situ laser transmission measurements, and low-magnification microscopic or visual observation of the jets indicated that, at 250 bar, sodium chloride solutions first pass through a two-phase, vapor-liquid state before solid salt is formed, while sodium sulfate solutions nucleate solids directly from a homogeneous supercritical-fluid phase. Sodium sulfate solids appeared much finer and also more aggregated than sodium chloride solids. Primary sodium sulfate particle diameters were typically between 1 and 3 μm, while some aggregates reached diameters up to about 20 μm. In contrast, sodium chloride solids ranged from 5− to 25-μm shell-like particles for a 0.5 wt %NaCl jet and 20− to 100-μm semispherical particles for a 10.0 wt % NaCl jet. At a subcritical pressure of 200 bar, the average particle size increased dramatically for both salts. In mixed NaCI/Na 2 SO 4 solutions at 250 bar, the extent of small particle nucleation of sodium sulfate decreased with increasing sodium chloride concentration in the jet feed. Both the observed morphology and mixture effects were explained in terms of different isobaric phase behavior.

Liquid-Liquid and Vapor-Liquid Equilibria in Water + Poly(ethylene glycol) + Sodium Sulfate

Abstract: In this work we have measured liquid-liquid equilibria (LLE) and vapor-liquid equilibria (VLE) in aqueous solutions of poly(ethylene glycol) (PEG) and sodium sulfate. The liquid-liquid equilibria have been determined over a range of polymer molar masses (1550-6000 g/mol), pH values (5.2-8.1), and temperatures (293.15-313.15 K) using a density-sound analyzer. The VLE in the system water+PEG 3000+sodium sulfate have been measured over the entire homogeneous mixing range at 293.15 and 313.15 K by vapor-pressure osmometry

The lon-chromatographic behavior of arsenite, arsenate, methylarsonic acid and dimethylarsinic acid on the hamilton PRP-X100 anion-exchange column

Abstract: The HPLC separation of arsenite, arsenate, methylarsonic acid and dimethylarsinic acid has been studied in the past but not in a systematic manner. The dependence of the retention times of these arsenic compounds on the pH of the mobile phase, on the concentration and the chemical composition of buffer solutions (phosphate, acetate, potassium hydrogen phthalate) and on the presence of sodium sulfate or nickel sulfate in the mobile phase was investigated using a Hamilton PRP-X100 anion-exchange column. With a flame atomic absorption detector and arsenic concentrations of at least 10 mg dm−3 all investigated mobile phases will separate the four arsenic compounds at appropriate pH values in the range 4–8. The shortest analysis time (˜3 min) was achieved with a 0.006 mol dm−3 potassium hydrogen phthalate mobile phase at pH 4, the longest (˜10 min) with 0.006 mol dm−3 sodium sulfate at pH 5.9 at a flow rate of 1.5 cm3 min−1. With a graphite furnace atomic absorption detector at the required, much lower, flow rate of ˜0.2 cm3 min−1 acceptable separations were achievable only with the pH 6 phosphate buffer (0.03 mol dm−3) and the nickel sulfate solution (0.005 mol dm−3) as the mobile phase. To become detectable approximately 100 ng arsenic from each arsenic compound (100 μl injection) must be chromatographed with the phosphate buffer, and approximately 10 ng with the nickel sulfate solution.

Liquid-Liquid Equilibrium of Aqueous Mixtures of Poly(ethylene glycol) with Na2SO4 or NaCl

Abstract: Experimental liquid-liquid equilibrium phase diagrams, tie lines, and plait points were obtained for ternary systems consisting of water, sodium sulfate, and poly(ethylene glycol) 1000 at 301 K, poly(ethylene glycol) 3350 at 301 and 308 K, and poly(ethylene glycol) 8000 at 301 K. The equilibrium phase diagram of water, sodium chloride, and poly(ethylene glycol) 8000 at 333 K was also determined

Hydrogen consuming anodes for energy saving in sodium sulphate electrolysis

Abstract: Gas diffusion electrodes, made of PTFE-bonded carbon with precious metal catalysts, were investigated as hydrogen consuming anodes in sodium sulphate electrolysis. The catalysts used were platinum and palladium and mixtures of both metals, prepared by two different methods. Various metal meshes were used as current collector. The electrodes performed well in pure sulphuric acid (5–15 wt-%) and in mixtures with sodium sulphate (10 wt-%) at temperatures of 30 to 70°C and current densities up to 5 kA/m2. In long-term experiments, at a current density of 2.6 kA/m2, the electrodes were stable over three months. The electrodes were characterised by stationary current density/potential curves and by galvanostatic current interruption measurements.

Immobilization agent for industrial waste

Abstract: The immobilization agent for industrial waste according to the present invention is characterized by that it contains cement, ferrous chloride, iron oxalate and amorphous aluminium silicate, and it is preferred said ferrous chloride, iron oxalate and amorphous aluminium silicate are contained in it by mixing ferrous chloride and iron oxalate with amorphous aluminium silicate and granulating and heating the mixture in an inert gas stream. Further, according to the present invention, it may also contain at least one selected from the group consisting of potassium chloride, magnesium chloride, sodium chloride, cobalt chloride, aluminium sulfate, citric acid, calcium chloride and sodium sulfate in addition to the compounds mentioned above.

Corrosion Behavior of Aluminum-Lithium Alloys

Abstract: Corrosion behavior of three aluminum-lithium (Al-Li) alloys was investigated in aerated 0.5 M sodium sulfate (Na2SO4), deaerated 3.5% sodium chloride (NaCl), and aerated 3.5% NaCl. Corrosi...

Stability of rhbFGF as Determined by UV Spectroscopic Measurements of Turbidity

Abstract: Loss of potency of a protein formulation due to precipitation of the protein is a major concern to the pharmaceutical scientist. A simple screening method was developed to study the effect of excipients on protein precipitation. It will not provide accurate stability data but it allows the rejection of excipients that may interfere with the stability of a protein formulation. The method is based on measuring the increase in turbidity at 277 nm by UV-spectroscopy and was sensitive and reproducible enough to obtain data within 15 hr at 30°C or 40°C, which will allow prediction of precipitation behavior that would need with conventional methods 2–3 years. Human recombinant basic fibroblast growth factor (rhbFGF or bFGF) was formulated at various pH-values as well as in the presence of various concentrations of preservatives, surfactants, gelling agent, EDTA, NaCl, sodium sulfate, sucrose, and glycosaminoglycans (GAG). Most excipients increased bFGF aggregation rate when their concentrations were increased. Exceptions were heparin and some of its derivatives, and sodium sulfate; high concentrations of sucrose and sodium chloride suppressed aggregation.

Kinetics of the coupled transport of vanadium(IV) from sulfate solutions through supported liquid membranes

Abstract: In this paper, the coupled transport of vanadium(IV) through supported liquid membranes containing bis(2-ethylhexyl) phosphoric acid was modeled. The experiments were carried out in a stirred permeation cell with well-defined hydrodynamics. The possibility of the application of the measured transport rates for determining the kinetic parameters of solvent extraction reaction was also investigated. The calculated rates were found to be in good agreement with the measured ones (average standard error, 5%). Under the conditions studied, the transport process was mainly governed by interfacial chemical reaction and partly by combined membrane diffusion in some runs.

Production of potassium sulfate using differential contacting

Abstract: A process for the manufacture of potassium sulfate from a sodium sulfate source, potash and water, comprising the steps of: (a) introducing the sodium sulfate source, water and potash into a differential countercurrent contactor; and (b) causing the sodium sulfate source, potash and water to contact differentially to produce potassium sulfate.

Enthalpies of interaction between dimethyldioctadecylammonium bromide vesicles in aqueous-solution and either dipicolinate or sulfate anions

Abstract: Injection of small aliquots of dipicolinate anions (sodium salt) into an aqueous solution containing dimethyl-dioctadecylammonium bromide (DOAB) vesicles is endothermic at 50 °C, becoming first more and then less endothermic. The injection process is effectively athermal for solutions containing more than equimolar amounts of DOAB and dipicolinate anions. A similar pattern is observed when small aliquots of sodium sulfate(aq) are injected into DOAB(aq). The overall patterns of enthalpy changes are attributed to the vesicle–dianion interaction which is exothermic and head-group dehydration with bromide ion displacement which is endothermic. Neverthless, a complexity emerges if the solutions include a buffer which turns out to play a less than passive role. This conclusion is supported by differential scanning microcalorimetry for DOAB(aq) in the presence and absence of HEPES buffer.

Surface Grafting onto Barium Sulfate: Polymerization of Acrylamide Initiated by the System Consisting of Alcoholic Hydroxyl Groups on the Surface and Ceric Ion

Abstract: To modify the surface of barium sulfate, the grafting of polymers onto the surface by the polymerization of acrylamide (AAm) initiated by the system consisting of eerie ion and alcoholic hydroxyl groups on the surface was investigated. Barium sulfate modified by 12-hydroxystearate (BaSO4-HS) was prepared by the reaction of barium chloride with sodium sulfate containing a small amount of sodium 12-hydroxystearate. The presence of 12-hydroxystearate groups on the BaSO4 surface was confirmed by XPS analysis and infrared spectra. It was found that the graft polymerization of AAm is initiated by the system consisting of eerie ion and BaSO4-HS to give poly (AAm)-grafted BaSO4. This indicated that the grafted polymer chains are propagated from surface radicals formed by the redox reaction of eerie ion with 12-hydroxystearate groups on the surface. The polymerization rate (R p) of AAm initiated by the redox system was given by R p = k[AAm][Ce(IV)][BaSO4-HS] where k is constant, [AAm] is AAm concentration...

Oxidation of DL-penicillamine by chromium(VI). Kinetics of formation of the thioester intermediate

Abstract: The kinetics of formation of the thioester involved as an intermediate in the reaction between chromium(VI) and DL-penicillamine in aqueous media (pH = 1–8) containing different buffers (acetate, citrate, and phosphate) has been studied by monitoring the disappearance of chromium(VI) at 370 nm and application of the initial-rates method. The initial rate is directly proportional to the initial concentrations of both oxidant and reductant, and the rate vs. pH plots show bell-shaped profiles. The reaction is catalyzed by the buffer present in the medium, the catalytic power of each buffer increasing in the order acetate < citrate < phosphate. This is explained in terms of a mechanism involving the formation of a complex between the acidic form of the buffer and HCrO4− previous to the formation of the thioester. Potassium chloride and sodium sulfate do not seem to have important specific effects on the reaction rate, their effect being that of an acceleration of the reaction as the ionic strength increases. ...

Gas sensor for detecting quality of food

Abstract: PROBLEM TO BE SOLVED: To simply, rapidly and inexpensively evaluate the quality of processed food such as soup by constituting a sensor element of indium oxide having lithium sulfate or sodium sulfate dispersed therein. SOLUTION: Indium oxide having lithium sulfate or sodium sulfate dispersed therein is used as a sensor element material. This material is a semiconductor gas sensor material showing an excellent response characteristic (electric resistance value change) to dimethyl disulfide being a component found out in a flavor fraction of soups. The dispersion amt. of lithium sulfate or sodium sulfate to indium oxide is 0.1-10wt.%, especially pref., 1-5wt.%. For example, a sensor element is produced by applying a sensor material (powder) kneaded with water to be formed into a pasty state to an alumina insulating pipe having tow Pt wires wound therearound as electrodes at an interval of 3.0mm and drying the coated pipe at room temp. before baking the same in air at 700 deg.C for 4hr.

Sodium lanthanum(III) sulfate monohydrate, NaLa(SO4)2.H2O.

Abstract: The structure of NaLaIII(SO4)2.H2O consists of distorted Na-O6 octahedra, La-O9 complexes in the form of distorted tricapped trigonal prisms, and slightly irregular tetrahedral sulfate ions. All bond distances fall within normal limits. The sulfate ions manifest rigid-body behavior but this is not the case for either of the cation complexes. The single water molecule is modelled as having O-atom disorder but an ordered H atom. Hydrogen bonds involve only sulfate O atoms as acceptors. The absolute structure has been determined.

Producing process for potassium sulfate

Abstract: The present invention relates to a new technology for making potassium sulphate. In order to simplifying the technologic process for more easy operation decreasing the mechanical loss, saving refrigeration quantity and lowering productive cost, said invention adopts a technological process of twice conversion and once evaporation technique to convert sodium sulfate and potassium chloride into potassium sulfate. Compared with the traditional cryothermal method, since the refrigerating procedure is saved, so that the operation is easy and convenient for each ton of potassium sulfate product, it can save 480 K joule of refrigeration quantity.