Showing papers on "Sodium sulfate published in 1995"

Effect of magnesium sulfate and sodium sulfate on the durability performance of plain and blended cements

Abstract: In this investigation, mortar specimens made with two plain cements, Type I and V, and blended cements, made with fly ash, silica fume, and blast furnace slag, were exposed to sodium-sulfate and magnesium-sulfate solutions. The performance of these cements, in both the environments, was evaluated by measuring expansion and determining reduction in compressive strength. The data indicate that while the performance of all blended cements, particularly those made with silica fume, was generally excellent in the sodium-sulfate environment, their performance in the magnesium-sulfate environment was not satisfactory. A similar trend was observed in mortar specimens made with a water-cement ratio of 0.35. The type of cement did not have any significant influence on the performance of either plain or blended cements in both environments. The deterioration of plain and blended cements in sodium-sulfate and magnesium-sulfate environments is attributed to the initial reaction of sodium sulfate and magnesium sulfate with calcium hydroxide. The reduction of calcium hydroxide in blended cements provides an opportunity to magnesium sulfate to react more directly with the primary and secondary calcium silicate hydrate due to the destabilization of these phases by magnesium hydroxide. Comparatively, lower deterioration of blended cements exposed to the sodium-sulfate environment is attributed to the reduced calcium hydroxide, which significantly mitigates the sulfate attack in these cements.

Pharmaceutical multiple unit particulate formulation in the form of coated cores

Abstract: A pharmaceutical multiple unit particulate formulation in the form of coated cores which includes a pharmaceutically acceptable carrier selected from calcium carbonate, calcium silicate, calcium magnesium silicate, calcium phosphate, kaolin, sodium hydrogen carbonate, sodium sulfate, barium carbonate, barium sulfate, magnesium sulfate, magnesium carbonate, and activated carbon, and an active substance in a layer on the outer surface of the cores.

Interactive effects of sodium chloride, sodium sulfate, calcium sulfate, and calcium chloride on snapbean growth, photosynthesis, and ion uptake

Abstract: Excessive sodium (Na) accumulation in soil, which can be a problem for production agriculture in arid and semiarid regions, may be ameliorated by calcium (Ca). The mechanisms of Ca amelioration of Na stress in plants have received much more attention than has the effect of the anion of the Ca salt. Our objective was to determine the relative effects of the chloride (Cl‐) and sulfate (SO4 2‐) anions on Ca amelioration of Na stress. We exposed Phaseolus vulgaris L., cv. Contender seedlings growing in 1‐L styrofoam pots under greenhouse conditions to sodum chloride (NaCl) or sodium sulfate (Na2SO4) at concentrations of 0, 15, 30, 45, and 60 mmol/L combined with either 15 and 30 mmol/L of calcium sulfate (CaSO4) or calcium chloride (CaCl2). Plants in each styrofoam pot were irrigated with 300 mL of salt solution (leaching fraction = 0.25) every fourth day for four weeks. Increasing Na concentration decreased shoot dry weight, number and weight of pods, and number of nodules. The photo‐ synthesis rate...

Application of a quartz crystal microbalance to the study of copper corrosion in acid solution inhibited by triazole-iodide protective films

Abstract: When one uses one side of a quartz crystal microbalance as the working electrode in electrochemical experiments, mass changes can be monitored continuously with a sensitivity of a few nanograms per square centimeter. In this study the working electrode consisted of electrolytically deposited copper, exposed to 0.1M sodium sulfate at pH 3, open to the atmosphere and in some cases containing H{sub 2}O{sub 2}. Upon addition of one of the inhibitors, benzotriazole (BTA), tolyltriazole (TTA), carboxy-benzotriazole (CBT), or these inhibitors plus potassium iodide, the rate of frequency change decreases markedly. After removal of the inhibitors from the corrosive medium by fast solution exchange there is a marked continuing protective effect of the inhibitor films in the cases of BTA + KI and TTA + KI with the latter being the most stable and protective of all of the films. The results were qualitatively the same in the more corrosive solution containing H{sub 2}O{sub 2}.

Simultaneous Solubility of Ammonia and Carbon-Dioxide in Aqueous-Solutions of Sodium-Sulfate in the Temperature-Range 313-393-K and Pressures Up to 3 MPa

Abstract: The solubility of weak electrolyte gases such as ammonia, carbon dioxide, sulfur dioxide, or hydrogen cyanide must be known for process design in many applications. Typical examples are applications in the chemical and oil-related industries, the production of fertilizers, and applications in environmental protection. Correlating and predicting the simultaneous solubility of ammonia and sour gases in aqueous phases are difficult tasks due to chemical reactions in the liquid phase resulting in the presence of ionic species. Furthermore, the liquid phase often contains other strong electrolytes, and solid phases might precipitate. The simultaneous solubility of ammonia and carbon dioxide in aqueous solutions of sodium sulfate was measured in the temperature range 313--393 K at total pressures up to 3 MPa. Experimental results are reported and compared to correlations and predictions. Predicted results generally agree well with experimental data.

Photocatalytic reduction of nitrite on CdS

Abstract: CdS catalysts, prepared using difference precursors, were characterized and tested for the photocatalytic reduction of nitrite to ammonia using sodium sulphate and sodium sulphite as sacrificial agents. The catalyst prepared from cadmium nitrate and sodium sulphide and treated at 623 K showed maximum activity. The activity was enhanced by loading with noble metals, such as Ru, Pd or Ir, or by the use of hole transferring agents, such as RuO2. The photoefficiency for the photocatalytic reduction of nitrite to ammonia was found to be 2.6%.

Co-production of potassium sulfate, sodium sulfate and sodium chloride

Abstract: A process for producing potassium sulfate, sodium sulfate, and sodium chloride from potash and a sodium sulfate/water source, wherein potash (12), sodium sulfate (14), slurry (34) from the recovery stage and brine (18) from the gaserite decomposition stage (20) are introduced to a first stage (10), wherein the sodium sulfate and potash dissolve, such that glaserite is precipitated. The slurry is concentrated and delivered (22) to the glaserite decomposition stage (20) along with water (24). Potash is introduced directly (8) and/or via stream (22) by introducing excess potash into stage (10). The potassium sulfate solids are separated, washed and dried to give a potassium sulfate product (27). The mother liquor (18) removed from the reactor is returned to the glaserite production stage (10). The brine (26) produced in the production of glaserite (10) is evaporated in an evaporative crystallizer (28). The removal of water (30) produces a supersaturation of sodium chloride, which precipitates out of solution.

Co-production of potassium sulfate and sodium sulfate

Abstract: A process for producing potassium sulfate or potassium sulfate and sodium sulfate from potash and a sodium sulfate/water source, which includes: (a) subjecting a sodium sulfate source to conversion with potash in an aqueous medium to yield glaserite precipitate and a first mother liquor; (b) converting the glaserite precipitate with potash and water to produce a potassium sulfate precipitate and a second mother liquor; (c) returning the second mother liquor to step (a); (d) subjecting the first mother liquor to treatment, such as evaporative crystallization, such that a sodium chloride and sodium sulfate solids mixture or pure sodium chloride is precipitated in a third mother liquor; (e) subjecting the solids from step (d) to a sodium sulfate/water source to produce anhydrous sodium sulfate; and (f) returning the third mother liquor for conversion to potassium salts.

Concentration of Sodium Sulfate from Pickle Liquor of Tannery Effluent by Electrodialysis

Abstract: An electrodialysis technique using indigeneously prepared interpolymer membranes and a laboratory-scale electrodialysis unit having an effective area of 25 cm x 12 cm with 20 pairs of ion-exchange membranes was used for the concentration of sodium sulfate of pickle liquor by the recycling method. In the first stage the sodium sulfate in the effluent was concentrated three and half times with respect to the original effluents, thereby rendering the concentrate usable in the tannery process. The diluate of first stage solution was further subjected to electrodialysis in a once through pass system, and the total dissolved solids content of the second stage diluation was brought down to less than 1000 ppm. This process offers the possibility of either reusing the water or safely discharging it. The parameters voltage, flow rate, and change of concentration with fresh effluent were investigated. The energy requirement and current efficiency were also calculated.

Precipitated silica having high sodium sulfate content

Abstract: Particles comprising particulate amorphous precipitated silica in association with from 5 to 10 percent by weight sodium sulfate and less than 10 percent by weight water, wherein the percentages are based on the weight of the silica, the sodium sulfate, and the water, which particles have a BET surface area of from 100 to 300 m 2 /g, a total intruded volume from 1.8 to 3.6 cm 3 /g, and a DBP oil absorption of from 180 to 320 cm 3 /100 g, may be employed in microporous battery separators to introduce all or a portion of the desired sodium sulfate to the battery electrolyte. Moreover the enhanced amount of sodium sulfate enhances silica characteristics and battery separator production.

Electrochemical and In Situ Scanning Force Microscopy Investigation of Anion Effects on Ag(111) Electrode Surfaces

Abstract: In situ atomic force microscope (AFM) and lateral force microscope (LFFM) images of Ag(111) electrode surfaces in fluoride, sulfate, perchlorate, and chloride containing electrolytes have been obtained under potential control. Short range images reveal only the Ag(111) structure in each of these anions, indicating that the anions are weakly bound to the electrode surface or form a (1 x 1) overlayer. Long range images show that in both the perchlorate and chloride solutions the surface and steps are blurred at positive potentials while at negative potentials the images are clear. This effect is not seen with either sulfate or fluoride. The blurring is associated with step formation and roughening on the Ag(111) electrode. The blurring in chloride containing solutions is associated with increased mobility of surface Ag atoms while Cl{sup {minus}} is adsorbed on the surface. This increased mobility also gives rise to step formation. In the perchlorate solutions, the step formation behavior is presumably a consequence of residual chloride arising from either contamination or perchlorate reduction.

Parametric analysis of phenol adsorption onto polymeric adsorbents

Abstract: In water pollution control, treatment methodologies such as biological degradation, adsorption, ion exchange, chemical oxidation, membrane separations, incineration, and stream stripping, have been applied for the removal of organic contaminant, but the use of polymeric adsorbent resins is an interesting option for recovery where the economics of solvents or chemical regeneration of the adsorbent are favorable. Distribution equilibria have been investigated for the adsorption of phenol on two macroporous adsorbent resins (Amberlite XAD-4 and Lewatit OC-1064). The experiments were done using a batch technique. The effects of solution pH, temperature, and ionic strength were studied. Results with a new commercial resin (Lewatit OC 1064) have been compared with measurements on the well-established adsorbent resin Amberlite XAD-4. The Langmuir equation was selected to analyze the effect of pH, temperature, and ionic strength on the equilibrium. The influence of the pH has been interpreted in terms of the phenol dissociation. The fraction of free water has been considered in evaluating the influence of the sodium sulfate concentration.

Electrolysis of weak black liquor Part II: Effect of process parameters on the energy efficiency of the electrolytic cell

Abstract: A laboratory study of the effects of process parameters on the performance of weak black liquor (WBL) electrolysis cells showed that anode material, current density and temperature are critical to the operation. The two latter variables showed an interaction effect upon the operation of the cell. In terms of energy efficiency, the IrO2 anode performed better than the Pt anode. The addition of sodium sulfate to the WBL was beneficial to the energy efficiency. No chlorine gas was produced when electrolyzing WBL containing sodium chloride within the pH range 5.4 to 13.

Method for sodium carbonate compound recovery and formation of ammonium sulfate

Abstract: There is disclosed a process for recovering sodium bicarbonate and forming ammonium sulfate from a source containing sodium sulfate. The method involves contacting the sodium sulfate in solution with carbon dioxide and a compound containing ammonia. Sodium bicarbonate is precipitated in high purity from the solution. It is important to maintain the temperature of the source solution at or above 32° C. This provision eliminates contamination of hydrates or ammonium bicarbonate components. The filtrate of the sodium bicarbonate reaction can be further processed to yield an ammonium sulfate product in the concentrated liquid or precipitated form in high purity. The basic process can be expanded to be combined with a conventional Claus process for sulphur recovery as a Tail Gas Unit, combined with lime injection to result in gypsum precipitation or can be further employed in a wet scrubbing process for FGD schemes.

Orientational disorder in lithium sodium sulfate

Abstract: Results of Raman, x‐ray diffraction, and differential scanning calorimetry studies of lithium sodium sulfate (LiNaSO4) doped with Cd2+ are presented. The x‐ray diffraction and differential scanning calorimetry data show that there is no significant change in the room temperature structure over the substitutional range studied. Raman spectra of Cd2+ substituted lithium sodium sulfate are compared with the temperature dependent spectra of pure LiNaSO4 and found to be qualitatively similar, reflecting the increasing breakdown of factor group correlated SO2−4 vibrations with increasing Cd2+ concentration.

In vivo modification of 3'-phosphoadenosine 5'-phosphosulfate and sulfate by infusion of sodium sulfate, cysteine, and methionine.

Abstract: The importance of tissue sulfate concentrations in regulating 3'-phosphoadenosine 5'-phosphosulfate (PAPS) synthesis is not known. Therefore, this study was conducted to determine the influence of increased availability of inorganic sulfate on steady-state PAPS concentrations in various tissues. To increase tissue sulfate concentrations, 2-16 mmol/kg of sodium sulfate and sulfur-containing amino acids (cysteine or methionine) were infused intravenously for 2 hr into pentobarbital-anesthetized rats. Serial blood samples were taken during the infusion and analyzed for sulfate concentrations. After 2 hr of infusion, liver, kidney, and brain were removed for quantification of tissue PAPS and sulfate concentrations. Infusion of sodium sulfate, cysteine, and methionine increased serum and tissue sulfate concentrations in a dose- and time-dependent manner. Serum sulfate concentrations increased from 0.8 to 14 mM during the infusion of sodium sulfate, whereas infusions of cysteine and methionine increased serum sulfate concentrations to 4.8 and 2.0 mM, respectively. Tissue sulfate concentrations also increased during sulfate infusion. Liver sulfate concentration increased from 0.8 to 4.8 mM, kidney concentration increased from 0.6 to 31 mM, and brain concentration increased from 0.1 to 0.6 mM. Similar to the serum sulfate concentrations, sulfate infusion was the most effective in increasing tissue sulfate concentrations, cysteine was intermediate, and methionine the least effective. Although sulfate concentrations in liver, kidney, and brain increased 6-, 50-, and 6-fold by infusing sulfate, respectively; tissue PAPS levels were not altered markedly. Hepatic PAPS concentrations increased significantly (30-35%) only when infused with the higher doses (8 or 16 mmol/kg/2 hr) of sodium sulfate.(ABSTRACT TRUNCATED AT 250 WORDS)

Concrete mix, process for preparing same, an additive for concrete mix, and process for preparing same

Abstract: A new concrete mix sodium nitrate, sodium carbonate, sodium sulfate, calcium chloride, calcium carbide, lime, cement, coarse aggregate and sand in a percent ratio of (0.51-0.70):(0.56-0.58):(0.66-0.90):(0.05-0.10):(0.17-0.40):(0.05-0.01):(25-30):(29.25-12):(30-35) mixed with 13.75 to 20% of water. A process for preparing the composition involves comminution of certain components to a predetermined range of particle size and a treatment to insure certain ranges of moisture content of various components of the composition.

Method for solidifying radioactive waste liquid containing sodium sulfate

Abstract: PURPOSE:To provide a method for solidifying a radioactive waste liquid containing sodium sulfate to stably stock and exhaust the sulfate for a long period. CONSTITUTION:The method for solidifying a radioactive waste liquid containing sodium sulfate comprises the steps of adding boric acid or baron oxide, glass forming substance or glass forming substance and metal to become glass forming component or glass forming substance and metal to become glass forming component to the liquid containing the sulfate, then heating to melt it, and incorporating sodium generated by decomposing the sodium sulfate into glass as the glass forming component.

Redetermination of sodium cerium(III) sulfate monohydrate, NaCe(SO4)2.H2O.

Abstract: The structure of sodium cerium sulfate monohydrate, NaCeIII(SO4)2.H2O, comprises distorted NaO6 octahedra, CeO9 polyhedra in the form of distorted tricapped trigonal prisms, and slightly irregular tetrahedral sulfate ions. This structure is isomorphic with that of NaLaIII(SO4)2.H2O. All bonds fall within normal limits. The sulfate ion manifested rigid-body behavior but neither of the cation complexes did. As in the previous structural analysis of the La analog [Blackburn & Gerkin (1994). Acta Cryst. C50, 835-838], the water molecule is modelled as having O-atom disorder but with an ordered H atom. Hydrogen bonds involve only sulfate O atoms as acceptors. The anisotropic atomic displacement parameters are found to be in good agreement with the corresponding parameters determined for the La analog, but in poor agreement with those previously reported for the title salt by Lindgren [Acta Chem. Scand. Ser. A, (1977), 31, 591-594]. Taken together, the data establish that the lack of correction for absorption in the previous study of the Ce salt, rather than some intrinsic property of the Ce salt, is responsible for the displacement parameter discrepancies. The absolute structure has been determined.

Adsorption of Maleimide and Its Derivatives on an Iron Electrode in Acidic and Neutral Media

Abstract: The impedance method was applied to the study of the adsorption of maleimide, N-(p-aminophenyl)-maleimide, and N-(p-nitrophenyl)maleimide on a polycrystalline iron electrode in neutral and acidic media. It was found that the addition of maleimide and its derivatives to a sodium sulfate or a sulfuric acid solution, respectively, leads to the decrease of the iron double layer capacitance. It was shown that the adsorption of the substances investigated was described by Frumkin's isotherm. A correlation is found between the adsorption parameters, determined electrochemically, and the data obtained by quantum-chemical calculations.

Arsenate precipitation using ferric iron in acidic conditions

Abstract: Arsenates (i.e., As(V)) can be removed from aqueous solution by precipitation with ferric iron (i.e., Fe(III)). The chemistry of arsenic acid describes the main properties of arsenates. This triprotic acid resembles the phosphoric acid system. For example, free arsenate ions (i.e., AsO{sub 4}{sup 3-}), like free phosphates, are present in significant concentration at pH values above pK{sub a,3}. On the other hand, the concentration of free ferric iron in solution, Fe{sup 3+}, is limited by ferric hydroxide precipitation and hydroxy complexation under neutral or basic conditions. Fe{sup 3+} is the predominant iron form only under very acidic conditions. Therefore, the absence of either ferric ions or arsenate ligands prevents ferric arsenate (FeAsO{sub 4}) precipitation in extreme pH conditions. Precipitation studies using ferric chloride show that the formation of ferric arsenate in water containing 0.667 mM/L (50 mg/L as As) is favored in the pH range between 3 and 4. Ferric iron dose required to remove arsenic from solution increases with pH in the range of 3 to 10. Sludge production also increases with increasing pH conditions. Optimum ferric iron doses at pH 3 and 4 are 4.8 and 10.0 mM/L, respectively, where the arsenate is removed from solution by 98.72more » and 99.68 percent. Corresponding iron requirement to arsenate ratios at these two pH conditions are 7.2 and 15.0. Adverse effects on arsenic removal are observed at pH = 3, where the concentration of applied ferric iron exceeds the optimal dose. This effect is probably due to charge reversal on the surface of the precipitates. Overdosing above the optimal iron concentration at pH = 4 does not reduce treatment efficiency significantly. Presence of sodium chloride in solution at a concentration of 171 mM/L (10,000 mg/L as NaCl) does not impair system performance. However, sodium sulfate at a concentration of 104 mM/L (10,000 mg/L) affects adversely treatment performance.« less