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Showing papers on "Ammonium hydroxide published in 2012"


Journal ArticleDOI
TL;DR: In this article, aniline oligomers obtained in 1 mol L−1 ammonium hydroxide as microspheres have been analyzed and shown to be brown, nonconducting, and composed of tens of anilines constitutional units.
Abstract: This paper deals with aniline oligomers produced by the oxidation of aniline with ammonium peroxydisulfate under alkaline conditions. Oligomers obtained in 1 mol L−1 ammonium hydroxide as microspheres have been analyzed. They are brown, non-conducting, and are composed of tens of aniline constitutional units. They contain oxygen in semiquinonoid and quinonoid constitutional units or both, and sulfur in sulfonic or sulfate groups. Phenazine-like units in the oligomers have been identified by UV-visible spectra and the IR spectra support them. IR spectroscopic analysis of fractions insoluble and soluble in chloroform suggests that aniline oligomers are not uniform and strong hydrogen bonding occurs in their structure. Aniline oligomers will be potentially useful in applications that do not require conductivity but use the redox or salt–base transitions typical of polyaniline. Their applicability is illustrated by the ability to reduce silver cations to silver, base–salt transitions and in the carbonization to nitrogen-containing carbons. Copyright © 2011 Society of Chemical Industry

135 citations


Journal ArticleDOI
TL;DR: In this article, a mixture template of triethylamine and tetraethyl ammonium hydroxide (TEAOH) was used to synthesize SAPO-34 for the reaction of methanol to olefins.

107 citations


Journal ArticleDOI
TL;DR: The addition of ammonium hydroxide resulted in the Zr-MOF with a slight lower adsorption ofCO(2) and CH(4), however, the selectivity of CO(2)/CH(4) is significantly enhanced.

106 citations


Journal ArticleDOI
TL;DR: The use of a less basic (pH 11) aqueous ammonium hydroxide (NH4OH) solvent system, NH4OH:DMF, allowed for the fabrication of HA mats having an average fiber diameter of 39±12nm and no degradation effects were observed and the continuous electrospinning of pure HA fibers was possible.

104 citations


Journal ArticleDOI
TL;DR: The efficiency of a batch microwave-assisted ammonia heating system was investigated as pretreatment for sweet sorghum bagasse and its effect on porosity, chemical composition, particle size, enzymatic hydrolysis and fermentation into ethanol evaluated.

97 citations


Journal ArticleDOI
TL;DR: In this paper, the mechanism for the growth of ZnO was studied in ammonium hydroxide solution at pH near 11 (0.3 M NH4OH), and the products formed at 20-90 °C and ambient pressure were characterised using Fourier Transform Infrared Spectrograph (FTIR), X-ray Photon Spectroscopy (XPS), XRD and secondary ion mass spectroscopy(SIMS).
Abstract: The mechanism for hydrothermal growth of ZnO was studied in ammonium hydroxide solution at pH near 11 (0.3 M NH4OH). The products formed at 20–90 °C and ambient pressure were characterised using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Photon Spectroscopy (XPS), X-ray Diffraction (XRD) and Secondary Ion Mass Spectroscopy (SIMS). Under these conditions, the growth of ZnO occurs via the initial precipitation of e-Zn(OH)2 (Wulfingite), which subsequently dehydrates, to form Wurtzite ZnO. Isotope tracking experiments show that most of the oxygen atoms do not mix with water during the conversion from Wulfingite to ZnO, and thus that the reaction proceeds primarily in the solid phase rather than through dissolution then reprecipitation. XPS results show that the surface of hydrothermal ZnO consists primarily of zinc hydroxide at lower temperatures, and there is a significant fraction of zinc hydroxide persisting at higher temperatures. Together these results show that much of the solid-solution interface is mainly comprised of zinc hydroxide not ZnO. These findings may have implications for understanding how small organic molecules can be used to control the morphology of zinc oxide crystals grown under hydrothermal conditions.

91 citations


Journal ArticleDOI
TL;DR: It was found that addition of ammonium hydroxide produced some effects on the structure and adsorption behavior of Zr-MOFs, and the crystal size of ZR-MOF was reduced with increasing amount of the additive.
Abstract: Several zirconium-based metal–organic frameworks (Zr-MOFs) have been synthesized using ammonium hydroxide as an additive in the synthesis process. Their physicochemical properties have been characterized by N2 adsorption/desorption, XRD, SEM, FTIR, and TGA, and their application in CO2 adsorption was evaluated. It was found that addition of ammonium hydroxide produced some effects on the structure and adsorption behavior of Zr-MOFs. The pore size and pore volume of Zr-MOFs were enhanced with the additive, however, specific surface area of Zr-MOFs was reduced. Using an ammonium hydroxide additive, the crystal size of Zr-MOF was reduced with increasing amount of the additive. All the samples presented strong thermal stability. Adsorption tests showed that capacity of CO2 adsorption on the Zr-MOFs under standard conditions was reduced due to decreased micropore fractions. However, modified Zr-MOFs had significantly lower adsorption heat. The adsorption capacity of carbon dioxide was increased at high pressure, reaching 8.63 mmol g−1 at 987 kPa for Zr-MOF-NH4-2.

78 citations


Journal ArticleDOI
TL;DR: The utility of chitosan as an excellent platform for impregnating the ionic liquid, tetraoctylammonium bromide by ultrasonication and its subsequent adsorption for chromium(VI) is reported and translated into action in the form of practical application to a real sample containing chromium.

72 citations


Journal ArticleDOI
TL;DR: The alkyl chain length effect has been analyzed by precise measurements such as densities, ultrasonic sound velocity, and viscosity of these ILs with polar solvent, N-methyl-2-pyrrolidone (NMP), over the full composition range as a function of temperature.
Abstract: Mixing of ionic liquids (ILs) with molecular solvent can expand the range of structural properties and the scope of molecular interactions between the molecules of the solvents. Exploiting of these phenomena essentially require a basic fundamental understanding of mixing behavior of ILs with molecular solvents. In this context, a series of protic ILs possessing tetra-alkyl ammonium cation [R4N]+ with commonly used anion hydroxide [OH]− were synthesized and characterized by temperature dependent thermophysical properties. The ILs [R4N]+[OH]− are varying only in the length of alkyl chain (R is methyl, ethyl, propyl, or butyl) of tetra-alkyl ammonium on the cationic part. The ILs used for the present study included tetramethyl ammonium hydroxide [(CH3)4N]+[OH]− (TMAH), tetraethyl ammonium hydroxide [(C2H5)4N]+[OH]− (TEAH), tetrapropyl ammonium hydroxide [(C3H7)4N]+[OH]− (TPAH) and tetrabutyl ammonium hydroxide [(C4H9)4N]+[OH]− (TBAH). The alkyl chain length effect has been analyzed by precise measurements su...

68 citations


Journal ArticleDOI
TL;DR: In this paper, the uptake of modified chitosan resins toward Brilliant Blue R250 (BBR250) from aqueous media was studied using batch method, which indicated an endothermic spontaneous adsorption process and kinetically followed the pseudo-second order model, Fickian diffusion low and Elovich model.

68 citations


Journal ArticleDOI
TL;DR: The two-stage pretreatment, treatment with NH4OH at 120 °C temperature for 15 min followed by treatment with H3PO4 at 140 °C for 30 min, impressively provided the highest total monomeric sugar yield of 71.6 g/100 g dried biomass.

Patent
07 Mar 2012
TL;DR: In this article, the authors present methods, systems, and compositions for preparing a solid biomass for fast pyrolysis, which includes contacting the solid biomass with an inorganic material present in an effective amount.
Abstract: Aspects of the present invention relate to methods, systems, and compositions for preparing a solid biomass for fast pyrolysis. The method includes contacting the solid biomass with an inorganic material present in an effective amount for increasing fast pyrolysis yield of an organic liquid product (e.g., bio-oil). In various embodiments, the inorganic material is selected from the group consisting of aluminum sulfate, aluminum nitrate, aluminum chloride, aluminum hydroxide, ammonium hydroxide, magnesium hydroxide, potassium hydroxide, and combinations thereof.

Journal Article
TL;DR: In this paper, a series of protic ionic liquids (ILs) possessing tetra-alkyl ammonium cation with commonly used anion hydroxide [OH] was synthesized and characterized by temperature dependent thermophysical properties.
Abstract: Mixing of ionic liquids (ILs) with molecular solvent can expand the range of structural properties and the scope of molecular interactions between the molecules of the solvents. Exploiting of these phenomena essentially require a basic fundamental understanding of mixing behavior of ILs with molecular solvents. In this context, a series of protic ILs possessing tetra-alkyl ammonium cation [R₄N]⁺ with commonly used anion hydroxide [OH]⁻ were synthesized and characterized by temperature dependent thermophysical properties. The ILs [R₄N]⁺[OH]⁻ are varying only in the length of alkyl chain (R is methyl, ethyl, propyl, or butyl) of tetra-alkyl ammonium on the cationic part. The ILs used for the present study included tetramethyl ammonium hydroxide [(CH₃)₄N]⁺[OH]⁻ (TMAH), tetraethyl ammonium hydroxide [(C₂H₅)₄N]⁺[OH]⁻ (TEAH), tetrapropyl ammonium hydroxide [(C₃H₇)₄N]⁺[OH]⁻ (TPAH) and tetrabutyl ammonium hydroxide [(C₄H₉)₄N]⁺[OH]⁻ (TBAH). The alkyl chain length effect has been analyzed by precise measurements such as densities (ρ), ultrasonic sound velocity (u), and viscosity (η) of these ILs with polar solvent, N-methyl-2-pyrrolidone (NMP), over the full composition range as a function of temperature. The excess molar volume (Vᴱ), the deviation in isentropic compressibility (Δκₛ) and deviation in viscosity (Δη) were predicted using these properties as a function of the concentration of ILs. Redlich–Kister polynomial was used to correlate the results. A qualitative analysis of the results is discussed in terms of the ion-dipole, ion-pair interactions, and hydrogen bonding between ILs and NMP molecules. Later, the hydrogen bonding features between ILs and NMP were also analyzed using a molecular modeling program with the help of HyperChem 7.

Journal ArticleDOI
TL;DR: Three different stationary phases (sulfoalkylbetaine zwitterionic, polyhydroxyethyl aspartamide and ethylene bridge hybrid (BEH) with trifunctionally bonded amide), operating at hydrophilic interaction liquid chromatographic (HILIC) mode, have been assayed and compared for the analysis of complex mixtures of galactooligosaccharides (GOS).

Journal ArticleDOI
TL;DR: In this paper, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential thermal analysis (DTA), and field emission scanning electron microscopy (FESEM) were used to characterize ZSM-11 particles.

Journal ArticleDOI
TL;DR: Using a combination of scanning electron microscopy and X-ray diffraction techniques, the mechanism for ZnO formation was studied by simply heating an aqueous solution containing zinc salts and ammonium hydroxide to 85 °C as discussed by the authors.

Journal ArticleDOI
TL;DR: The SAA treatment was shown to remove significant amounts of lignin without strongly affecting lign in functional groups or structure and activation energy of control and pretreated wheat straw was found to be decreased.
Abstract: Production of renewable fuels and chemicals from lignocellulosic feedstocks requires an efficient pretreatment technology to allow ready access of polysaccharides for cellulolytic enzymes during saccharification. The effect of pretreatment on wheat straw through a low-temperature and low-pressure soaking aqueous ammonia (SAA) process was investigated in this study using Fourier transform infrared (FTIR), pyrolysis–gas chromatography/mass spectroscopy (Py-GC/MS), solid and liquid state nuclear magnetic resonance (NMR), and thermogravimetry/differential thermogravimetry (TG/DTG) to demonstrate the changes in lignin, hemicellulose, and cellulose structure. After treatment of 60 mesh wheat straw particles for 60 h with 28–30% ammonium hydroxide (1:10 solid/liquid) at 50 °C, sugar recovery increased from 14% (untreated) to 67% (SAA treated). The FTIR study revealed a substantial decrease in absorbance of lignin peaks. Solid and liquid state NMR showed minimal lignin structural changes with significant composit...

Journal ArticleDOI
TL;DR: In this paper, the effect of aging time and calcination temperature on structural properties of synthesized nanopowder was investigated by X-ray diffractometry (XRD), simultaneous thermal analysis (STA), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM) and transmission electron spectroscopy (TEM) analytical methods.
Abstract: In the present work, the cerium nitrate hexa-hydrate and ammonium hydroxide, used as the starting materials and the weakly agglomerated cerium oxide nanoparticles was synthesized by simple and cost effective reverse co-precipitation method. The effect of aging time and calcination temperature on structural properties of synthesized nanopowder was investigated by X-ray diffractometry (XRD), simultaneous thermal analysis (STA), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM) and transmission electron spectroscopy (TEM) analytical methods. The investigation showed that aging of the precipitated precursors has pronounced effect on the decreasing of the agglomeration, increase in the crystallinity and the crystallite size of the final product obtained after calcination. Also, increase in the calcination temperature led to the appreciable increase in the crystallite size as well as the crystallinity. Key words: Aging time, ammonium hydroxide, calcination temperature, ceria nanoparticles, reverse co-precipitation.

Journal ArticleDOI
Abstract: Highly crystalline magnesium hydroxide (Mg(OH)2) was obtained by sol–gel process using magnesium nitrate (Mg(NO3)2) with ammonium hydroxide (NH4OH) in a hydrophilic ionic liquid, 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) as a medium. Crystallite size of Mg(OH)2 obtained in [Bmim]Cl was larger than that obtained in 2-propanol (used as a medium for comparison), which indicates that [Bmim]Cl worked as a template. The obtained Mg(OH)2 was transformed to magnesium oxide (MgO) by heat treatment under atmospheric pressure. After heat treatment, crystallite size of the MgO obtained in [Bmim]Cl was also larger than that obtained in 2-propanol, reflecting the crystallinity of Mg(OH)2 before heat treatment. Polystyrene (PS)/Mg(OH)2 composite particles were successfully prepared by seeded dispersion sol–gel process in [Bmim]Cl in the presence of PS seed particles. The composite particles had smooth surfaces and core–shell morphology consisting of PS core and Mg(OH)2 shell having high crystallinity. The Mg(OH)2 ...

Journal ArticleDOI
TL;DR: In this paper, an anionic iron(III) porphyrin (FePor) family was applied to zinc hydroxide chloride (ZHC) to demonstrate the catalytic activity of the solids.
Abstract: This work describes the immobilization of an anionic iron(III) porphyrin (FePor) family on zinc hydroxide chloride (ZHC), a layered hydroxide salt prepared by reacting an aqueous zinc chloride solution with an ammonium hydroxide solution. The FePor immobilization was performed at room temperature under magnetic stirring, under air atmosphere, of each complex ethanol solution and the ZHC solid support suspension. The materials obtained were characterized by X-ray powder diffraction (XRPD), ultraviolet-visible spectroscopy (UV–vis) (solid samples), Fourier transform infrared spectroscopy (FTIR) and electron paramagnetic resonance (EPR). The catalytic activity of the solids was investigated in cyclooctene, cyclohexane and n -heptane heterogeneous catalytic oxidation reactions with iodosylbenzene as the oxygen donor. The solid catalyst's reutilization capacity was also investigated and the heterogeneous character of the catalytic process was confirmed. The compounds and the catalytic activity of FePor-ZHC were compared with the synthesis and catalytic activity of the same FePor immobilized on zinc hydroxide nitrate (ZHN). Though the matrixes are similar, the results obtained were exactly the opposite when the selectivity was analyzed.

Journal ArticleDOI
TL;DR: In this article, hexagonal tungsten trioxide (WO3) nanorods were prepared from ammonium metatungstate, tetrapropyl ammonium hydroxide and potassium chloride.

Journal ArticleDOI
TL;DR: A series of poly(arylene ether sulfone)s containing tetra-quaternary ammonium hydroxide on fluorenyl group (QAPAES-OH) were synthesized via polycondensation, chloromethylation, quaternization, and subsequent ion exchange reactions as discussed by the authors.

Journal ArticleDOI
15 Jan 2012
TL;DR: In both cases shell aging processes are observed to continue beyond initial shell formation suggesting that trans-shell diffusion of reactants may be feasible, or that rapid hydrolysis is required in order to load high concentrations of the reactants into the internal phase before significant shell formation.
Abstract: Water core/silica shell microcapsules are prepared via the hydrolysis and subsequent polycondensation of tetraethoxysilane in a surfactant stabilised water-in-oil emulsion. The relationship between preparative conditions, including pH and silane concentration, has been related to final particle structure. Furthermore, the nature of the catalyst has been found to affect the mechanism by which the shells are formed, with an interfacial polymerisation proposed for ammonium hydroxide catalysed synthesis in agreement with previous reports and a new colloidosome assembly process for sodium hydroxide catalysis. In both cases shell aging processes are observed to continue beyond initial shell formation suggesting that trans-shell diffusion of reactants may be feasible, or that rapid hydrolysis is required in order to load high concentrations of the reactants into the internal phase before significant shell formation.

Journal ArticleDOI
TL;DR: In this article, a self-crosslinked alkaline electrolyte membrane with high hydroxide ion conductivity, excellent dimensional stability and extraordinary solvent resistance stability is synthesized successfully without using any catalyst or separate crosslinker.

Journal ArticleDOI
TL;DR: In this paper, a phenol-based activated carbon (AC) was seriatim amino-fluorinated with solution of ammonium hydroxide and hydrofluoric acid in varying ratio to fabricate electrode materials for use in an electric double-layer capacitor (EDLC).

Journal ArticleDOI
TL;DR: In this paper, the physicochemical properties of the catalysts precursors vary with the precipitating agent, which shows a significant influence in their catalytic performance, and it is worth mentioning that the catalyst prepared using Na2CO3 shows significant activity in this reaction even at temperatures as low as 400°C.

Journal ArticleDOI
TL;DR: In this article, a novel approach to achieve phase-pure?-TaON films is described by the controlled nitridation of Ta2O5 films under a flow of ammonia gas (ammonolysis), which was obtained by bubbling argon through an aqueous ammonium hydroxide solution followed by a 5 A molecular sieve to remove the water.

Patent
04 Jul 2012
TL;DR: In this paper, a method for preparing tetrapropyl ammonium hydroxide by utilizing bipolar membrane electrodialysis was proposed, and the method comprises the following steps of: using a tetraplastic ammonium bromide aqueous solution as a raw material, processing the tetraPropyl quaternary ammonium salt solution through a microporous filter, and then enabling the processed triconyclic ammonium ion salt solution to enter a material liquid room of a bipolar membrane ELECTrodialyzing device.
Abstract: The invention discloses a method for preparing tetrapropyl ammonium hydroxide by utilizing bipolar membrane electrodialysis, and the method comprises the following steps of: using a tetrapropyl ammonium bromide aqueous solution as a raw material, processing the tetrapropyl quaternary ammonium salt aqueous solution through a microporous filter, and then enabling the processed tetrapropyl quaternary ammonium salt aqueous solution to enter a material liquid room of a bipolar membrane electrodialyzing device, respectively adding water in an acid room and an alkali room, respectively adding a sodium sulfate solution in pole liquid rooms, controlling the current density, the voltage and the temperature of the bipolar membrane electrodialyzing device to be 150-600 A/M2, 20-300 V and 5-45DEG C respectively, carrying out circulating cooling through chilled saline water in a circulating coil pipe by using an electrodialyzing compartment in a running process, stopping running when the conductivity of the material liquid room is decreased to below 2000 [mu]s/cm, obtaining a tetrapropylammonium hydroxide solution in the alkali room, and recycling a hydrobromic acid solution in the acid room. By using the method, the raw material cost is low; the selectivity is multiple; the purity of the tetrapropyl ammonium hydroxide is high; hydrobromic acid further can be recovered; and the generation of a pollutant in the process is effectively avoided.

Journal ArticleDOI
TL;DR: In this article, a method for vulcanizing natural rubber by using glutaraldehyde was introduced, and the results revealed an improvement in mechanical and thermal properties by vulcanization.
Abstract: A novel and inexpensive method for vulcanizing natural rubber by using glutaraldehyde was introduced. The vulcanized rubber samples were prepared by adding various amounts of glutaraldehyde to medium ammonia natural rubber latex. Cross-linking reaction occurred only in the presence of ammonium hydroxide in natural rubber latex upon the addition of glutaraldehyde. Cross-linked rubber has been obtained by reacting natural rubber with pentane-1,5-diylidenediamine formed from the reaction between glutaraldehyde and ammonia. The vulcanized materials were characterized by mechanical analysis and thermogravimetry. The results revealed an improvement in mechanical and thermal properties by vulcanization. Activation energy of degradation has been calculated using the Horowitz-Metzger equation. The cross-link density of the vulcanized rubber was determined from swelling experiments in benzene. Fourier transform infrared spectroscopy has been employed to confirm the cross-linking reaction between rubber mol...

Journal ArticleDOI
TL;DR: A method has been developed to reduce the mass spectrometric ion signal suppression associated with the use of TFA as an additive in LC mobile phases through post-column infusion of diluted NH(4)OH solution to LC eluents.
Abstract: A method has been developed to reduce the mass spectrometric ion signal suppression associated with the use of TFA as an additive in LC mobile phases. Through post-column infusion of diluted NH4OH solution to LC eluents, the ammonium ion introduced causes the neutral analyte-TFA ion pair to dissociate which consequently releases the protonated analyte as free ions into the gas phase (through regular electrospray ionization mechanisms). An ion signal improvement from 1.2 to 20 times for a variety of compounds had been achieved through the application of this method. The molar ratios of NH4OH:TFA which result in a reduction of signal suppression were determined to be between 0.5:1 and 50:1. In addition, it was shown that this NH4OH infusion method could reduce the level of doubly-charged species and the product ions formed via in-source collision. The use of diluted NH4OH solution is favorable since it is compatible with mass spectrometry analysis, and it is applicable in both positive and negative-ion generation mode. Copyright © 2012 John Wiley & Sons, Ltd.