Showing papers on "Sodium sulfate published in 2011"

Facile preparation and enhanced capacitance of the polyaniline/sodium alginate nanofiber network for supercapacitors.

Abstract: A porous and mat-like polyaniline/sodium alginate (PANI/SA) composite with excellent electrochemical properties was polymerized in an aqueous solution with sodium sulfate as a template. Ultraviolet–visible spectra, X-ray diffraction pattern, and Fourier transform infrared spectra were employed to characterize the PANI/SA composite, indicating that the PANI/SA composite was successfully prepared. The PANI/SA nanofibers with uniform diameters from 50 to 100 nm can be observed on scanning electron microscopy. Cyclic voltammetry and galvanostatic charge/discharge tests were carried out to investigate the electrochemical properties. The PANI/SA nanostructure electrode exhibits an excellent specific capacitance as high as 2093 F g–1, long cycle life, and fast reflect of oxidation/reduction on high current changes. The remarkable electrochemical characteristic is attributed to the nanostructured electrode materials, which generates a high electrode/electrolyte contact area and short path lengths for electronic t...

Sulfate Separation from Aqueous Alkaline Solutions by Selective Crystallization of Alkali Metal Coordination Capsules

Abstract: Self-assembly of a tris(urea) anion receptor with Na2SO4 or K2SO4 yields crystalline capsules held together by coordinating Na+ or K+ cations and hydrogen-bonding water bridges, with the sulfate anions encapsulated inside urea-lined cavities. The sodium-based capsules can be selectively crystallized in excellent yield from highly competitive aqueous alkaline solutions (∼6 M Na+, pH 14), thereby providing for the first time a viable approach to sulfate separation from nuclear wastes.

Salt Effect on the Aqueous Two-Phase System PEG 8000−Sodium Sulfate

Abstract: The effect of added salt (NaCl or KCl) on the polyethylene glycol 8000 (PEG)−sodium sulfate (Na2SO4) aqueous two-phase system (ATPS), containing 0.01 mol·L−1 of sodium phosphate buffer (NaPB), pH 7.4, has been investigated at 296.15 K. Phase diagrams determined by the cloud point method, including tie-lines assigned from mass phase ratios according to the lever arm rule, are presented for the different PEG 8000−Na2SO4 ATPSs, all containing 0.01 mol·L−1 NaPB, pH 7.4, and increasing the concentration of a neutral salt, such as NaCl or KCl, up to 1.0 mol·L−1. Experimental binodal results were satisfactorily correlated with an empirical mathematical model, the Merchuk equation. The results indicate that the addition of both salts causes a depression of the binodal relatively to that for the salt-free system. The salting-out ability of the cations follows the Hofmeister series (Na+ > K+) and can be related to the ions Gibbs free energy of hydration (ΔGhyd).

Sulfate transfer through concrete: Migration and diffusion results

Abstract: This paper presents a study on the effect of sulfate ions on concrete. The sulfate attack is approached in two different ways: results in natural diffusion are compared to migration results. Both sodium sulfate and magnesium sulfate are used as test agents. The comparison is presented in terms of concentration profiles and amounts of sulfate reacting with the cementitious matrix, together with mechanical resistances. It is shown that the electrical field has impact on the transfer of sulfate: when Mg 2+ is used as the counter-ion, the penetration depth proves to be larger in migration than the depth obtained with sodium sulfate. It is the opposite case in natural diffusion. A possible explanation could be found in the kinetics of brucite formation. Finally, the combination of magnesium sulfate with the electrokinetic technique results in significant mechanical strength losses after 6 months of test, while natural diffusion attacks lead to a much smaller loss.

The effect of chemical treatment on reduction of aflatoxins and ochratoxin A in black and white pepper during washing

Abstract: The effect of 18 different chemicals, which included acidic compounds (sulfuric acid, chloridric acid, phosphoric acid, benzoic acid, citric acid, acetic acid), alkaline compounds (ammonia, sodium bicarbonate, sodium hydroxide, potassium hydroxide, calcium hydroxide), salts (acetate ammonium, sodium bisulfite, sodium hydrosulfite, sodium chloride, sodium sulfate) and oxidising agents (hydrogen peroxide, sodium hypochlorite), on the reduction of aflatoxins B1, B2, G1 and G2 and ochratoxin A (OTA) was investigated in black and white pepper. OTA and aflatoxins were determined using HPLC after immunoaffinity column clean-up. Almost all of the applied chemicals showed a significant degree of reduction on mycotoxins (p < 0.05). The lowest and highest reduction of aflatoxin B1, which is the most dangerous aflatoxin, was 20.5% ± 2.7% using benzoic acid and 54.5% ± 2.7% using sodium hydroxide. There was no significant difference between black and white peppers (p < 0.05).

The chemomechanics of crystallization during rewetting of limestone impregnated with sodium sulfate

Abstract: Breakdown of porous materials by salts occurs when growing crystals exert pressure on the pore walls, inducing stress in the material that exceeds its tensile strength. In this work, we quantify the mechanical stresses caused by a particularly destructive mechanism: the dissolution of an anhydrate (thenardite, Na2SO4) followed by precipitation of a hydrated salt (mirabilite, Na2SO4·10H2O). Stresses are measured using a composite specimen consisting of a plate of glass bonded to a plate of limestone (CaCO3) whose pores are impregnated with thenardite. As water wicks into the limestone, thenardite dissolves and mirabilite precipitates. The limestone expands from the pressure exerted by the salt resulting in deflection of the composite, and the stresses can be obtained from an elastic analysis. Synchrotron x-ray diffraction reveals the dissolution–crystallization rate. Numerical modeling shows that the stresses are affected by the kinetics of crystallization and dissolution, permeability, and mechanical properties of the stone, allowing us to determine the amount of salt that causes material fracture.

Sulfate Attack on Concrete: Effect of Partial Immersion

Abstract: Traditionally, the extent of sulfate attack is qualified through visual rating or quantified by the percent expansion of slender bars completely submerged in sulfate solution. There are currently no standardized test methods that take into account the change in engineering properties because of deleterious mechanisms. Moreover, the exposure regime used to evaluate sulfate attack, complete immersion, is not typically representative of that encountered in the field. For these reasons, the objective of the research presented herein is to quantify the degree of sodium sulfate attack through the degradation of mechanical properties, specifically the compressive and splitting tensile load capacities of standard cylindrical specimens. A novel exposure regime is utilized wherein the specimens are only partially submerged in 5% sodium sulfate solution, creating an evaporation front similar to that of field exposure. It was found that the portion submerged in sulfate solution, although visually pristine, was the weaker portion of the cylinder for both mechanical tests, even though the other half showed extensive signs of surface disintegration caused by salt crystallization.

Middle-effective pumping aid

Abstract: The invention relates to a neutral pumping agent which is characterized in that it is composed of following components and weight percent: 10-20 wt.% of coarse dust (sodium lignin sulfonate), 40-60 wt.% of liquid material (36% beta- naphthalene sulfonic acid formaldehyde condensation conpound solution), 0.5-1.0 wt.% of exciting agent (thiamin), 0.5-1.0 wt.% of sodium gluconate and 0.5-1.0 wt.% ofTG, 0.2-0.3 wt.% of air entraining agent (lauryl sodium sulfate), 25-30 wt.% of water. It polymerizes to form a compound with a certain structure in an environment no more than 100 DEG C. The final product is formed after cleaning ducts, removing ammonia, reducing chlorin, and adjusting pH value. The product has a high stability, a wide cement adaptability, a strong protective force, a high waterreducing ratio, a good Environment Protection and can obviously improve a plurality of physical mechanics capacity such as workability, water retention, pumpability of the pumping beton and indurating beton, especially for the beton with a large volume and high pump bear.

Method for directly roasting and processing spent lithium ion batteries and recycling valuable metals

Abstract: The invention relates to a method for directly roasting and treating spent lithium ion batteries and recycling valuable metals, in particular to a method for recycling and treating spent lithium ion bThe invention relates to a method for directly roasting and treating spent lithium ion batteries and recycling valuable metals, in particular to a method for recycling and treating spent lithium ion bleaching solution and obtain a cobalt product and a copper product; using sodium carbonate to precipitate the metal lithium from the leaching solution after the cobalt and the copper are removed; ana leaching solution and obtain a cobalt product and a copper product; using sodium carbonate to precipitate the metal lithium from the leaching solution after the cobalt and the copper are removed; and enabling the leaching solution to return treatment heat so as to secondarily treat materials. The invention has a metal leaching rate higher than 99.5 percent and a metal recovery rate higher than 9d enabling the leaching solution to return treatment heat so as to secondarily treat materials. The invention has a metal leaching rate higher than 99.5 percent and a metal recovery rate higher than 99 percent.9 percent.atteries using lithium cobalt oxide as an anode material. The method comprises the following steps: firstly, remove organic binder on an organic diaphragm material and an electrode material in the batatteries using lithium cobalt oxide as an anode material. The method comprises the following steps: firstly, remove organic binder on an organic diaphragm material and an electrode material in the batteries by roasting at a temperature of 500 DEG C to 850 DEG C; crushing and mixing the roasted battery material with sodium sulfate (or potassium sulfate) and concentrated sulfuric acid before size miteries by roasting at a temperature of 500 DEG C to 850 DEG C; crushing and mixing the roasted battery material with sodium sulfate (or potassium sulfate) and concentrated sulfuric acid before size mixing; carrying out secondary heat treatment in an electric stove at a temperature of 350 DEG C to 600 DEG C to convert metals in the spent lithium ion batteries, such as cobalt, copper, lithium, and txing; carrying out secondary heat treatment in an electric stove at a temperature of 350 DEG C to 600 DEG C to convert metals in the spent lithium ion batteries, such as cobalt, copper, lithium, and the like into easily water-soluble sulfate which is leached by water or a dilute sulphuric acid solution; then, using an organic extracting agent to respectively extract the cobalt and the copper fromhe like into easily water-soluble sulfate which is leached by water or a dilute sulphuric acid solution; then, using an organic extracting agent to respectively extract the cobalt and the copper froma

An Ion-Exchange Approach to the Crystal Design of Barium Sulfate in the Presence of Ionic Surfactants

Abstract: Chemical reaction occurring between an insoluble solid and a saltwater solution relates to an exchange of ionic components and is therefore referred to as ion-exchange reaction. In this paper, we used the ion-exchange reaction of solid-state barium carbonate (BaCO3) and aqueous sodium sulfate (Na2SO4) for the crystal design of barium sulfate (BaSO4). This anionic ion-exchange, driven by the solubility discrepancy between BaCO3 and BaSO4, was rate-limited chemical transformation owing to the slow release of barium ions, resulting in the unusual BaSO4 crystallite with the bounded (200), (002), and (210) faces. Therein, cationic surfactant of cetyltrimethylammonium bromide (CTAB) exerted almost no influence on the morphological control of crystalline products. In a striking contrast to this, the similar cationic surfactant of CTAOH (i.e., cetyltrimethylammonium hydroxide) promoted the crystal growth along the [020] direction. Surprisingly, the addition of anionic sodium dodecyl sulfate (SDS) enhanced the sur...

The Role of Sulfur Compounds in Coloring and Melting Kinetics of Industrial Glass

Abstract: Soda-lime-silica (SLS) glass is the most widely used of all commercial types of glass. This type of glass is mainly used for manufacturing windowpanes, household glassware and glass containers (e.g. bottles, jars) for foodstuffs and beverages. These types of end-products differ in their application, and production method (e.g., blowing and pressing for containers and glassware, float process for windows) as well as in their chemical composition. Nevertheless, they are all produced by melting mixed raw materials ( batch) in a glass furnace at maximum temperatures ranging between 1500–1600 °C. The batch consists mainly of silica sand, sodium carbonate (soda), lime, dolomite and variable amounts of glass cullet. Small quantities of alumina-bearing raw materials, fining agents (e.g., sodium sulfate), coloring and reducing/oxidizing agents are also added to the batch. For the production of SLS glass, sulfur containing raw materials (e.g. sulfates and sulfides) play an important role in determining the final product’s quality. These compounds are involved in the final part of the fusion process, known as the fining process. In this process, the decomposition of raw materials generates a large amount of gas. The evolution of those gases from the glass melt is enhanced by the presence of the sulfur compound (Kloužek et al. 2007). Moreover, sulfur compounds act as oxidizing (sulfates) or reducing (sulfides) agents, playing a decisive role in the coloring mechanism of the final glass. Sulfates also enhance the kinetics of the sand’s dissolution by wetting the sand grains at relatively low temperatures thereby, accelerating the melting process (Albayrak and Sengel 2008; Muller-Simon and Gitzhofer 2008; Daneo et al. 2006, 2009). In Table 1⇓, typical composition ranges for SLS containers glasses produced in Italy are reported in wt% of oxides (data from Stazione Sperimentale del Vetro, SSV). The total sulfur concentration in …

Solubilities of Sodium, Potassium, and Copper(II) Sulfates in Ethanol−Water Solutions

Abstract: The solubilities of (sodium and copper(II)) sulfate + ethanol + water mixtures have been determined at (278.15, 288.15, and 298.15) K and for the potassium sulfate + ethanol + water system at the same temperatures and also at (308.15 and 318.15) K. The equilibrium composition for different points has been calculated by means of refraction index and density measurements. An empirical correlation for the solubilities of the ternary mixtures has been used to correlate experimental values as a function of the solvent composition. Data fitting shows a good agreement with experimental values.

The influence of platinum on the oxidation and sodium sulfate induced hot corrosion of NiAl diffusion coatings

Abstract: Oxidation and corrosion properties at 900 degrees C of two coatings, one containing platinum and the other platinum-free, on IN792 were investigated. During the corrosion exposures, sodium sulfate salt was situated in the furnace together with the coated specimens. The temperature of the salt was kept above its melting point but lower than the temperature of the coating i.e. 900 degrees C. The exposure times ranged from 100 to 1000 h. The formed oxide scales were studied by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy and scanning transmission electron microscopy techniques. It is shown that the presence of Pt improves the protective properties of the coating against corrosion. The propagation stage of corrosion on the platinum-free coating is reached already after 100 h of exposure. On the other hand the scale formed on the platinum-rich samples still appeared to be protective even after 500 h. The details concerning structure and chemistry of the scales formed are presented and discussed.

Metastable Phase Equilibrium in the Aqueous Quaternary System (Li2SO4 + Na2SO4 + Li2B4O7 + Na2B4O7 + H2O) at 273.15 K

Abstract: The quaternary system (Li2SO4 + Na2SO4 + Li2B4O7 + Na2B4O7 + H2O) is one of the most important and basic subsystems of the brines located in the area of the Qinghai-Xizang (Tibet) Plateau. To make certain the solubility of the lithium, sodium, and borate changes with the temperature, the metastable equilibrium of the quaternary system (Li2SO4 + Na2SO4 + Li2B4O7 + Na2B4O7 + H2O) was investigated at 273.15 K using an isothermal evaporation method. The solubilities of the equilibrated solution were measured using chemical analytical methods. The crystalloid forms of the solid phase were determined using an X-ray diffraction method. This system is of a complex type, with a double salt of sodium and lithium sulfate (3Na2SO4·Li2SO4·12H2O) formed at 273.15 K. The phase diagram of this system consists of three invariant points, seven univariant curves, and five crystallization fields. Comparisons between the phase diagrams of this system at 273.15 K and at 288.15 K show that the crystallization forms and the size...