Showing papers on "Sodium sulfate published in 2008"
TL;DR: In this article, an updated phase diagram of the Na2SO4-H2O system based on a careful review of the available thermodynamic data of aqueous sodium sulfate and the crystalline phases is presented.
311 citations
TL;DR: The curved dependence of chemical shift and self-diffusion coefficient on the increase in concentration suggests that the premicelles grow as the concentration increases until a definite value when the size of the premicelle reaches that of the micelle, i.e., the system is likely dominated by the monomers and micelles.
Abstract: The mechanism of micelle formation of surfactants sodium dodecyl sulfate (SDS), n-hexyldecyltrimethylammonium bromide (CTAB) and Triton X-100 (TX-100) in heavy water solutions was studied by 1H NMR...
249 citations
TL;DR: The results show that the interfacial properties are of key importance for where and how the crystals form in sodium sulfate and sodium chloride in model situations: evaporating droplets and evaporation from square capillaries.
Abstract: Salt damage in stone results in part from crystallization of salts during drying. We study the evaporation of aqueous salt solutions and the crystallization growth for sodium sulfate and sodium chloride in model situations: evaporating droplets and evaporation from square capillaries. The results show that the interfacial properties are of key importance for where and how the crystals form. The consequences for the different forms of salt crystallization observed in practice are discussed.
210 citations
TL;DR: Adsorption of cationic methylene blue and anionic orange II onto unmodified and surfactant-modified zeolites was studied using a batch equilibration method, and the results suggested that 2% sodium dodecyl benzenesulfonate (SDBS)- and 3% sodium Dodecyl sulfate (SDS)-modifiedZeolites had higher adsorption capacities for methyleneblue than the unmodified zeOLite.
184 citations
TL;DR: In this paper, a thin-film composite (TFC) nanofiltration (NF) membrane was prepared through the interfacial polymerization between piperazine (PIP) and trimesoyl chloride (TMC) on the polysulphone support membrane.
133 citations
TL;DR: A mixture of rare earth double sulfates was produced from a Turkish bastnasite-containing pre-concentrate by sulfuric acid baking, subsequent water leaching and precipitation with sodium sulfate as discussed by the authors.
130 citations
TL;DR: In this article, a nanowall array of hydrous manganese dioxide MnO2·0.5H2O was deposited on cathodic substrates by the potentiostatic method from a mixed aqueous solution of MANGESE acetate and sodium sulfate.
Abstract: Nanowall arrays of hydrous manganese dioxide MnO2·0.5H2O were deposited on cathodic substrates by the potentiostatic method from a mixed aqueous solution of manganese acetate and sodium sulfate, an...
125 citations
TL;DR: In this article, the authors present data on engineering properties such as compressive strength, visual change and expansion of mortar specimens incorporating limestone filler subjected to severe sulfate attack at ambient temperature.
123 citations
TL;DR: Impedance measurements indicate that the ionic conductivity of these porous structures can be increased more than an order of magnitude over that observed for standard conducting polymer films and that the hybrid material displays peak specific capacitance of around 700 F/g as well as excellent reversibility and cyclability.
Abstract: A porous conducting polymer/heteropolyoxometalate hybrid material that displays high specific capacitance and low ionic resistance has been prepared for electrochemical supercapacitor applications. Polypyrrole/phosphomolybdate composite films were chemically synthesized in tetrahydrofuran in the presence of sodium sulfate, which acts as a porogen. While the phosphomolydic acid could be removed from the film upon rinsing with pure tetrahydrofuran or acetone, rinsing with water or methanol resulted in retention of the heteropolyoxometalate at a level high enough to easily observe its electrochemistry. The retained phosphomolybdate exhibits fast and reversible redox behavior, adding a significant amount of pseudocapacitance to the polymer. Porous films were obtained by leaching out the sodium sulfate porogen from the films using water. The morphology obtained using this method is altered by varying the monomer-to-porogen ratio. Increasing the porosity increases the rate at which the hybrid material can be ch...
116 citations
TL;DR: In this paper, the crystallization of sodium sulfate salts in Cordova Cream and Indiana limestones was investigated using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA).
Abstract: Crystallization pressure of salt crystals growing in confined pores is found to be the main cause for damage to stone and masonry. In this work, the crystallization of sodium sulfate salts in Cordova Cream and Indiana limestones is investigated using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The DSC experiments indicate that sodium heptahydrate always precipitates prior to the decahydrate (mirabilite), at a temperature between 15 and 7°C in the selected stones. The threshold supersaturation for the nucleation of heptahydrate is less than 2. In constrast, mirabilite precipitates close to or below 0°C and its crystallization pattern is completely different: precipitation takes place abruptly when the threshold supersaturation is reached, which is greater than 7. Indeed, the DSC and the DMA experiments reveal the rare nature of the nucleation of mirabilite for the investigated stones. The crystallization pressure exerted by heptahydrate does not cause damage under the conditions of the cooling experiments. In contrast, mirabilite exerts a very high crystallization pressure on the pore wall causing damage of the stone; moreover, the transient stress can remain for a long period of time since the relaxation process is slow.
95 citations
TL;DR: The obtained results demonstrate that surfactant-polymer interaction is governed by both electrostatic and hydrophobic interactions, and is cooperative in the presence of salt.
TL;DR: In this article, the anodically deposited nickel hydroxide electrodes are highly porous and composed of interconnected nanoflakes about 12-16 nm in thickness, and an optimal annealing temperature of 300°C is obtained in terms of the electrode's specific capacitance.
Abstract: Nanostructured nickel hydroxides are galvanostatically deposited onto a stainless steel substrate by a plating bath of nickel sulfate, sodium acetate, and sodium sulfate at room temperature. The anodically deposited nickel hydroxide electrodes are highly porous and composed of interconnected nanoflakes about 12-16 nm in thickness. Pore size of the deposited electrode increases with decreasing the depositing current density. X-ray diffraction patterns show that the deposited nickel hydroxide converts into nickel oxide at annealing temperature above 300°C. Annealing temperature influences both the electrical resistance and the grain size of the electrode and, consequently, determines the capacitive behavior of the electrode investigated by cyclic voltammetry in 1 M KOH aqueous solution. An optimal annealing temperature of 300°C is obtained in terms of the electrode's specific capacitance. An electrode with larger pores deposited at lower current density has a higher specific capacitance because larger pores facilitate the ion diffusion rate. An electrode with smaller pore size deposited at higher current density exhibits more kinetically reversible behaviors, resulting in a better high-rate capability.
TL;DR: In this paper, phase diagrams of aqueous two-phase systems composed of poly(ethylene) glycol (PEG) 1500, lithium sulfate, or magnesium sulfate were determined at (283.15, 305.65, and 313.15) K.
Abstract: Phase diagrams of aqueous two-phase systems composed of poly(ethylene) glycol (PEG) 1500, lithium sulfate, or magnesium sulfate were determined at (283.15, 298.15, and 313.15) K and of PEG 1500 + sodium sulfate were obtained at (278.15, 298.15, 305.65, and 313.15) K. The temperature effect on the position of the binodal curves was negligible, indicating a small enthalpic contribution to the phase separation process. The ability of the three salts to induce the formation of a biphasic system with PEG 1500 followed the order MgSO4 > Na2SO4 > Li2SO4.
TL;DR: In this article, a cyclic voltammetric (CV), galvanostatic, and potentiostatic strategies were used to prep nickel oxide films with various morphologies and structures.
TL;DR: In this article, the effect of sulfate ions on calcite growth rates is determined and a potential incorporation of sulfates ions is identified in the calcite during growth, and the spreading rate of 2-dimensional nuclei is also measured.
TL;DR: In this article, a composite cation exchange membrane for electrodialysis of sodium chloride has been proposed and its performance has been evaluated in terms of current efficiency and power consumption and the effect of current density, salt concentration and flow rate on efficiency has been studied.
TL;DR: The results showed that the swelling capacity was affected by various factors, such as polymerization temperature, concentration of initiator and crosslinker, and dose of AM, and salt bond was a potential crosslinking factor in the amphoteric hydrogel.
TL;DR: In this paper, the binding of SDS with chitosan has been investigated at room temperature (298 K) and isothermal titration calorimetry (ITC) allowed some conclusions to be drawn concerning the extent of the hydrophobic interactions.
TL;DR: The effect of ionic strength on association between the cationic polysaccharide chitosan and the anionic surfactant sodium dodecyl sulfate, SDS, has been studied in bulk solution and at the solid/liquid interface.
Abstract: The effect of ionic strength on association between the cationic polysaccharide chitosan and the anionic surfactant sodium dodecyl sulfate, SDS, has been studied in bulk solution and at the solid ...
TL;DR: In this article, the authors presented the results of a new energy-efficient hybrid ion exchange-nanofiltration (HIX-NF) process to desalinate brackish and sea water.
TL;DR: Experimental results indicated that hydroxyl radicals are the most probable oxidants responsible for BPA degradation and the precursors of hydrogen peroxide, andFerric ion showed better catalytic effect than that of ferrous ion, suggesting that the ferric ion was reduced by the intermediates formed during B PA degradation.
TL;DR: Porous nickel oxide films composed of intercrossing nanoflakes are potentiostatically deposited onto the stainless steel substrate by a plating bath of sodium acetate, nickel sulfate and sodium sulfate as mentioned in this paper.
TL;DR: In this article, a commercial phosphoric acid manufactured using wet process has been purified by minimizing the iron, cadmium, copper and fluoride content, and the efficiency of potassium amyl xanthate in minimizing iron content was found 79.19% with a small decrease of P 2 O 5.
TL;DR: In this article, the interaction of hydrophobic dye pyrene with sodium dodecyl sulphate (SDS), an anionic surfactant, was studied in the process of solubilization.
Abstract: The interaction of hydrophobic dye pyrene with sodium dodecyl sulphate (SDS), an anionic surfactant, was studied in the process of solubilization. Difference UV-Visible spectroscopy was used to carry out the study. The partition coefficient (Kx), and number of dye molecules incorporated per micelle (n) was calculated. High Kx value shows that pyrene is partitioned strongly from polar to nonpolar environment. Steady-state fluorescence spectroscopy is used to check the environment of the pyrene as it is a well-known fluorescent probe. Onset of slope in curves is used to determine the critical micelle concentration (CMC).
TL;DR: In this paper, the authors used hard synchrotron x-rays to detect the formation of this metastable heptahydrate on cooling a porous calcium silicate material saturated with sodium sulfate solution.
Abstract: It is well known that sodium sulfate causes salt crystallization damage in building materials and rocks. However since the early 1900s the existence of the metastable heptahydrate has been largely forgotten and almost entirely overlooked in scientific publications on salt damage mechanics and on terrestrial and planetary geochemistry. We use hard synchrotron x-rays to detect the formation of this metastable heptahydrate on cooling a porous calcium silicate material saturated with sodium sulfate solution. The heptahydrate persists indefinitely and transforms to mirabilite only below 0 °C. At the transformation, which is rapid, the solution is highly supersaturated with respect to mirabilite. We estimate that crystallization of the heptahydrate and of mirabilite have associated Correns pressures of about 9 and 19 MPa, respectively, exceeding the tensile strength of building stones. We detect lattice strains in the salts from x-ray measurements consistent with these values.
TL;DR: In this paper, a two-phase system made of polyethylene glycol (PEG)/sodium sulfate and PEG/potassium phosphate was studied and the optimal condition gave a K value for thaumatin partitioning of 24.15 with a yield of 96.02%.
TL;DR: In this article, the effect of glycerol on both micellar formation and the structural evolution of the SDS aggregates in the context of the action mechanism of the cosolvent has been studied.
Abstract: The effect of glycerol on both micellar formation and the structural evolution of the sodium dodecyl sulfate (SDS) aggregates in the context of the action mechanism of the cosolvent has been studied. The critical micelle concentration and the degree of counterion dissociation of the surfactant over a temperature range from 20°C to 40°C were obtained by the conductance method. The thermodynamic parameters of micellization were estimated by using the equilibrium model of micelle formation. The analysis of these parameters indicated that the lower aggregation of the surfactant is mainly due to a minor cohesive energy of the mixed solvent system in relation to the pure water. The effect of glycerol on the mean aggregation number of the micelles of SDS was analyzed by the static quenching method. It was found that the aggregation number decreased with the glycerol content. This reduction in the micellar size seems to be controlled by an increase in the surface area per headgroup, which was ascribed to a partic...
TL;DR: In this article, 0.304L and 316L steels were nitrided at 425°C for 30h and examined at various depths in 0.1M Na 2 SO 4 acidified to pH 3.0.
TL;DR: The paper reports on the chemical functionalization of glassy carbon electrodes with 4-bromobenzene (4-BBDT) and 4-(4'-nitrophenylazo)benzene diazonium tetrafluoroborate ( 4-NAB) salts in ionic liquids.
Abstract: The paper reports on the chemical functionalization of glassy carbon electrodes with 4-bromobenzene (4-BBDT) and 4-(4′-nitrophenylazo)benzene diazonium tetrafluoroborate (4-NAB) salts in ionic liquids. The reaction was carried out at room temperature in air without any external electrical bias in either hydrophobic (1-butyl-3-methylimidazolium hexafluorophosphate) or hydrophilic (1-butyl-3-methylimidazolium methyl sulfate) ionic liquids. The resulting surfaces were characterized using X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and electrochemical measurements. Electrochemical reduction of the terminal nitro groups allowed the determination of surface coverage and formation of an amine-terminated carbon surfaces. The results were compared to glassy carbon chemically modified in an aqueous solution in the presence of 1% sodium dodecyl sulfate (SDS) with the same diazonium salt. Furthermore, Raman spectroscopy coupled with electrochemical measurements allowed to distinguish between the reduc...
TL;DR: In this paper, mesoporous TiO 2 materials have been synthesized with the aid of benzyl alcohol (BA) as cosurfactant along with anionic surfactant sodium dodecyl sulfate (SDS) as the template/structure directing agent (SDA).