Showing papers on "Ammonium hydroxide published in 2007"

Synthesis and characterization of cage octa(aminopropylsilsesquioxane)

Abstract: The compound of cage octa(aminopropylsilsesquioxane) (POSS-NH2) was prepared in higher yield by the hydrolysis and polycondensation of trifunctional monomer H2NCH2CH2CH2Si(OC2H5)3 in the mixture of solvents acetonitrile and 1-propanol, with tetraethyl ammonium hydroxide (Et4NOH) as the catalyst. The effects of various parameters influencing the reaction, such as monomer concentration, nature of solvents, and the content of catalyst, were investigated. Results showed that the better values of these reactive factors were nH2O/nXSiY3 = 8–9/1 (molar ratio), nEt4NOH/nXSiY3 = 0.0045 (molar ratio), respectively. The use of acetonitrile as a solvent favors the deposition and formation of the product. The existence of the higher boiling pointing 1-propanol favors the higher reaction temperature, which accelerates the formation of octamer, reduces the reaction time and eventually increases the yield. The cage structure and its formula (H2NCH2CH2CH2)8Si8O12 of the synthetic compound were characterized by FTIR, MS, 1H, and 29Si NMR. TG curve of POSS-NH2 shows that the cage-like compound has high decomposition temperature and higher thermal residue than the theoretical values during the thermal processing. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2608–2614, 2007

Process for the treatment of lignocellulosic biomass

Abstract: A process for the treatment of biomass to render structural carbohydrates more accessible and/or digestible using concentrated ammonium hydroxide with or without anhydrous ammonia addition, is described. The process preferably uses steam to strip ammonia from the biomass for recycling. The process yields of monosaccharides from the structural carbohydrates are good, particularly as measured by the enzymatic hydrolysis of the structural carbohydrates. The monosaccharides are used as animal feeds and energy sources for ethanol production.

A novel co-precipitation synthesis of a new phosphor Lu2O3:Eu3+

Abstract: Europium-doped Lu 2 O 3 phosphors were prepared via a co-precipitation process. The influence of precipitants on morphology and dispersibility of the obtained Lu 2 O 3 powders were investigated. Precipitation was performed with three different precipitants, namely ammonium hydroxide (NH 3 ·H 2 O), ammonium hydrogen carbonate (NH 4 HCO 3 ), and the mixture of NH 3 ·H 2 O and NH 4 HCO 3 . Ultrafine, nearly monodispersed, weakly agglomerated and near-spherical lutetia powders could be obtained with mixed NH 3 ·H 2 O and NH 4 HCO 3 as the precipitant. The precipitate precursor with the mixed precipitant was believed to possess a basic carbonate composition and its thermal decomposition and phase evolution processes were investigated. Photoluminescence characteristics of Lu 2 O 3 :Eu 3+ phosphors obtained by this modified precipitation method were also studied.

Liquid extraction of metals from sulphate solutions by alkylphosphoric acids. I. Equilibrium distributions of copper, cobalt and nickel with di‐(2‐ethyl hexyl) phosphoric acid

Abstract: Liquid-liquid equilibrium data were obtained at 25° for the distribution of copper, cobalt and nickel between aqueous sulphate solutions and kerosene solutions of di-(2-ethyl hexyl) phosphoric acid (EHPA). Two mechanisms of extraction were observed. When the ratio (L) of organic phase equilibrium metal concentration to initial EHPA concentration was less than 0·1, the metals were extracted by the reaction: and a correlation for the equilibrium distribution coefficients was obtained from the thermodynamic equilibrium relationship for this reaction, taking into account metal ion complexing in the aqueous phase. Ammonium hydroxide and sodium hydroxide were used as alkalis for pH adjustment and similar distribution coefficients were obtained with both when L was less than 0·1. For L greater than 0·1, metal-EHPA polymers were also formed in the organic phase, a typical step in their formation being: Equilibrium relationships were obtained from consideration of the equilibrium constants of the typical step and the reaction for monomer formation. The nature of the alkali used for pH adjustment influenced the distribution coefficients when L exceeded 0·1, higher distribution coefficients being obtained with sodium hydroxide than with ammonium hydroxide.

Selective conversion of ethylbenzene into styrene over K2O/TiO2-ZrO2 catalysts: Unified effects of K2O and CO2

Abstract: By varying the composition of TiO2 and ZrO2, various TiO2-ZrO2 mixed oxide catalysts were prepared by co-precipitation method using ammonium hydroxide as a hydrolyzing agent. Similarly, TiO2 and ZrO2 isolated oxides were also prepared for the purpose of comparison. 60 mol% TiO2 + 40 mol% ZrO2 mixed oxide catalyst (here after simply termed as TiO2-ZrO2) was impregnated with different amounts of potassium oxide (K2O). These catalysts were characterized by BET surface area, X-ray diffraction (XRD) and temperature programmed desorption of NH3. K2O/TiO2-ZrO2 catalysts exhibited high performance towards the selective conversion of ethylbenzene into styrene in the presence of CO2, wherein K2O improved the conversion of ethylbenzene and selectivity of styrene acting as a basic promoter, similarly CO2 enhanced both conversion and selectivity acting as an oxidant as well as a diluent. The unified promotional effects of K2O and CO2 improved the conversion of ethylbenzene up to 60–65% at 95–99% selectivity levels of styrene.

Cationic water‐soluble polymers with the ability to remove arsenate through an ultrafiltration technique

Abstract: Different cationic water-soluble polymers with (R)4N+X− groups and pyridinium groups were prepared, and their arsenate retention performance was investigated with the liquid-phase polymer-based retention technique. Poly[3-(methacryloylamino)propyl]trimethylammonium chloride, poly[2-(acryloyloxy)ethyl]trimethylammonium chloride, poly(ar-vinylbenzyl)trimethylammonium chloride, poly[2-(acryloyloxy)ethyl]trimethylammonium methyl sulfate, poly(4-vinyl-1-methyl pyridinium)bromide, and poly[3-(methacryloylamino)propyl]dimethyl(3-sulfopropyl)ammonium hydroxide were prepared. The synthesis of the polymers by solution radical polymerization produced a yield higher than 77%. Structural analyses were performed with Fourier transform infrared and 1H-NMR spectroscopy and thermogravimetry/differential scanning calorimetry. Commercial poly(4-vinyl-1-methyl pyridinium)bromide and poly(ar-vinylbenzyl)trimethylammonium chloride were also used. The liquid-phase polymer-based retention technique was employed to study the retention of arsenate species. The polymer structure and exchange groups, such as methyl sulfate, chloride, bromide, and hydroxide, presented different properties for removing arsenate anions from aqueous solutions. The type of voluminous quaternary ammonium group present influenced arsenic retention. All the polymers could bind HAsO42− species from an aqueous solution more selectively at pHs 8 and 6 than at pH 4. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Method of preparing ceramic powders using chelate precursors

Abstract: Wet-chemical methods involving the use of water-soluble hydrolytically stable metal-ion chelate precursors and the use of a nonmetal-ion-containing strong base can be used in a coprecipitation procedure for the preparation of ceramic powders. Examples of the precipitants used include tetraalkylammonium hydroxides. A composition-modified barium titanate is one of the ceramic powders that can be produced. Certain metal-ion chelates can be prepared from 2-hydroxypropanoic acid and ammonium hydroxide.

Swelling Behavior of Poly(2‐hydroxyethyl Methacrylate‐co‐acrylic Acid‐co‐ammonium Acrylate) Hydrogels

Abstract: The purpose of this study was to prepare a series of pH‐sensitive hydrogels from 2‐hydroxyethyl methacrylate (HEMA), acrylic acid (AA), and ammonium acrylate, NH4Ac, which was obtained by neutralization of AA with ammonium hydroxide. Hydrogels were prepared by free radical copolymerization in aqueous solution in the presence of redox initiators, Na2S2O8/Na2S2O5, and crosslinker, ethylene glycol dimethacrylate, EGDMA. The copolymers were synthesized by varying AA, EGDMA, and NH4OH concentrations. The effect of pH, temperature, ionic strength, concentration of crosslinker, and AA content on the swelling behavior of the copolymeric gels were investigated. Equilibrium swelling studies, in the pH range of 2–8, were performed to determine the polymer mesh size (ξ), 14.17–127.6 A, molecular weight between crosslinks (M c ), 324–10229 g/mol, and crosslinking density (q), 0.012–0.366, by using the Flory‐Rehner equation. Copolymeric gels exhibited reversible change in their swelling behaviors in response to cycling...

Separation of proteins from grasses integrated with ammonia fiber explosion (afex) pretreatment and cellulose hydrolysis

Abstract: A process for extracting an aqueous ammonium hydroxide solution from a plant biomass after an Ammonia Fiber Explosion (AFEX) process step, is described. The proteins can be separated before or after a hydrolysis of sugar precursors (carbohydrates) from the biomass to produce sugars for fermentation to produce ethanol. The proteins are useful as animal feeds because of their amino acid food values.

Synthesis of Spinel CoFe2O4 Via the Co-Precipitation Method Using Tetraalkyl Ammonium Hydroxides as Precipitating Agents

Abstract: Spinel Cobalt ferrites were synthesized by the co-precipitation method using tetramethyl-, tetraethyl-, and tetrabutyl ammonium hydroxide as precipitating agents. The products were characterized by X-ray diffraction, scanning electron microscopy, atomic absorption spectroscopy, thermogravimetric analysis, and low-temperature nitrogen adsorption measurements. The influence of the length of the carbon chain of the precipitating agent on the progressive development of the spinel structure has been investigated as a function of thermal decomposition temperature. The degree of crystallization depends on the thermal decomposition temperature, and also on the type of precipitating agent used to form the precursor. Tetrabutyl ammonium hydroxide is the weakest base with the highest molecular weight among the three precipitating agents. An increase in the size of the tetraalkyl ammonium cation reduces the crystallite size and lattice parameter of cobalt ferrite spinel. It also appears to reduce the degree of particle aggregation significantly.

Synthesis and characterization of polymeric resins with aliphatic and aromatic amino ligands and their sorption behavior towards gold from ammonium hydroxide solutions

Abstract: The functional resins with amino ligands are synthesized by the modification of lightly crosslinked poly(vinylbenzyl chloride–divinylbenzene) matrix with the following amines: 1-methylpiperazine, ethylenediamine, dipropylamine, 1-methylimidazole, 2-mercapto-1-methylimidazole, 1,2-dimethylimidazole and 1-(3-aminopropyl) imidazole. Two methods of the modification reactions were employed, the first one is the traditional heating of the polymer with either neat amine or amine solution in an appropriate solvent, the second method is heating of the reaction mixture in a microwave reactor. The resultant resins show different degrees of modification depending on the applied method and contain 1.61–3.68 mmol of ligand/g. The 1-methylimidazole resin displays the highest affinity towards gold from ammonium buffer (100 g/dm 3 NH 3 · H 2 O, 50 g/dm 3 (NH 4 ) 2 SO 4 ). For this resin, the sorption is as high as 15.5 mg/g and log K d (distribution coefficient) value is 2.94. All resins are highly selective and they do not sorb copper amino complexes. These polymeric materials were characterized using nitrogen, sulfur and chlorine elemental analysis and FTIR spectroscopy.

Method of preparing ceramic powders using ammonium oxalate

Abstract: Wet-chemical methods involving the use of water-soluble hydrolytically stable metal-ion chelate precursors and an ammonium oxalate precipitant can be used in a coprecipitation procedure for the preparation of ceramic powders. Both the precursor solution and the ammonium oxalate precipitant solution are at neutral or near-neutral pH. A composition-modified barium titanate is one of the ceramic powders that can be produced. Certain metal-ion chelates can be prepared from 2-hydroxypropanoic acid and ammonium hydroxide.

Production of microbial growth stimulant with ammonia fiber explosion (AFEX) pretreatment and cellulose hydrolysis

Abstract: A process for producing a microbial growth stimulant (MGS) from a plant biomass is described. An ammonium hydroxide solution is used to extract a solution of proteins and ammonia from the biomass. Some of the proteins and ammonia are separated from the extracted solution to provide the MGS solution. The removed ammonia can be recycled and the proteins are useful as animal feeds.

Passivation of a Si(100) surface by S from solution

Abstract: A wet-chemical process has been developed to passivate the Si(100) surface with sulfur (S) in an aqueous solution. The solution contains an etchant for SiO 2 , ammonium hydroxide [NH 4 OH] and a passivant for the surface, ammonium sulfide [(NH 4 ) 2 S]. The compatibility of the etchant with the passivant allows SiO 2 , native or thermal, to be removed in situ from the surface. A fresh and clean Si(100) surface is exposed right before it is passivated by S. Schottky barrier heights of Al on S-passivated n- and p-type Si(100) show a greater sensitivity to Al work function and Si electron affinity, suggesting good-quality passivation.

A color resist remover composition for tft-lcd preparation

Abstract: The present invention relates to a colorful photoresist stripping solution composition for removing colorful photoresist patterns and coatings, which is used for recycling defective substrates during fabricating the color filter of a thin-film-transistor liquid crystal display, especially relates to a hydroxide with 1-20 weight% selected from inorganic base hydroxide, ammonium hydroxide, alkyl ammonium hydroxide having C1-C4 alkyl benzene alkyl ammonium hydroxide having C1-C4 alkyl; at least one compound having the C1-C4 selected from alkyl alkylene glycol ether or alkylene diol with 1-70 weight%; hydroxylamine with 0.5-10 weight%; alkoxyl alkylamine with 0.5-10 weight%; and the colorful photoresist stripping solution composition with the residual water. The composition of the invention can remove colorful photoresist and the coatings in a short period of time so that the invention can recycle defective substrates during fabricating the color filter, which would be discarded due to the difficulty of removing photoresist patterns in prior arts.

Post-cmp treating liquid and manufacturing method of semiconductor device using the same

Abstract: Post-CMP treating liquids are provided, one of which includes water, an amphoteric surfactant, an anionic surfactant, a complexing agent, resin particles having carboxylic group and sulfonyl group on their surfaces, a primary particle diameter thereof ranging from 10 to 60 nm, and tetramethyl ammonium hydroxide. Another includes water, polyphenol, an anionic surfactant, ethylene diamine tetraacetic acid, resin particles having carboxylic group and sulfonyl group on their surfaces, a primary particle diameter thereof ranging from 10 to 60 nm, and tetramethyl ammonium hydroxide. Both of the treating liquids have a pH ranging from 4 to 9, and exhibit a polishing rate both of an insulating film and a conductive film at a rate of 10 nm/min or less.

Thermal analysis of ammonium, mono-, DI-and triethanolammonium alginates

Abstract: Thermal behaviour of ammonium (NH4alg), mono- (MEAalg), di- (DEAalg) and triethanolammonium (TEAalg) salts of alginic acid (Halg) was investigated by thermogravimetry (TG) and differential scanning calorimetry (DSC). Salts were prepared by the direct reaction of alginic acid with the ammonium hydroxide and with the respective ethanolamines. After preparation the compounds were lyophilized during 24 h and characterized by FTIR spectroscopy and elemental analysis (C, H and N). Under air the compounds exhibited three successive thermal decomposition steps: dehydration, decomposition of the polymeric matrix and finally, burning of carbonaceous residue. Under nitrogen two steps (dehydration and decomposition) were observed. The stability order of this series of compounds was: TEAalg this series of compounds was: TEAalg

Effect of Catalyst on the Colloidal Silica Particle Growth in Direct Oxidation of Silicon

Abstract: Nano size silica particles were produced by direct oxidation of silicon powder in the water with the base catalysts. The average size of 10~100 nm was successfully prepared from the starting material of silicon powder with variable procession parameters such as silicon solid content, choice of catalyst and amount, the order of mixing, etc. The sodium hydroxide and ammonium hydroxide was chosen for the base catalysts and their amount and addition order were found to control the size of silica particles in the oxidation reaction. The limited amount of NH4OH as the first catalyst seemed to limit the number of nucleus particles, and the limited amount of NaOH further feeded only for particle growing rather than nucleus formation, thereby it was observed to be able to control the average size of particles to be as large as 100 nm. The possible mechanism of particle growth was suggested by solubility of silica and relative affinity of NH4 + and Na+ ions to the surface of SiO2.

Mycobacterium sp. smic-1 resistant to tetramethyl ammonium hydroxide and capable of using it as a carbon source and a method of decreasing or removing tetramethyl ammonium hydroxide in a sample

Abstract: A microorganism Methylobacterium extorquens SMIC-1 having improved resistance against tetramethyl ammonium hydroxide(TMAH) and being capable of growing with TMAH as a carbon source is provided to remove or reduce tetramethyl ammonium hydroxide having toxicity in wastewater. A microorganism Methylobacterium extorquens SMIC-1(KCTC 10946BP) has high resistance against tetramethyl ammonium hydroxide and is capable of growing in a medium containing TMAH as a carbon source. The tetramethyl ammonium hydroxide in a wastewater sample is removed or reduced by culturing Methylobacterium extorquens SMIC-1(KCTC 10946BP) immobilized on a carrier in the sample through batch cultivation or continuous cultivation, wherein the carrier is collagen, gelatin, agar, alginic acid, color quinine, cellulose, acetate, polyacryl amide, amide, polyurethane, polyvinylalcohol or polyethylene glycol.

Carbon Disulfide in Heterocyclic Organic Synthesis; Synthesis of Polyfunctionally Substituted Sulfur and Nitrogen Heteroaromatics

Abstract: Reaction of cayno acetamdie with carbon disulphide in alkaline medium, e.g., potassium hydroxide, or potassium ter butoxide gave the gem-dithiol (1). While in presence of ammonium hydroxide the ammonium salt (2) was obtained. Reactions of (1) or (2) with different reagents in different mediums gave pyridine, pyrimidines, thiophene, and thiopyranones derivatives.