Showing papers on "Ammonium hydroxide published in 2006"
TL;DR: In this paper, it was shown that the PANI morphology depends on the acidity conditions during the reaction rather than on the chemical nature of the acid, and that PANI nanotubes were also produced when aniline was oxidized in the absence of any acid.
Abstract: The courses of aniline oxidation with ammonium peroxydisulfate in aqueous solutions of strong (sulfuric) and in weak (acetic) acids, followed by temperature and acidity changes, are different. In solutions of sulfuric acid, granular polyaniline (PANI) was produced; in solutions of acetic acid, PANI nanotubes were obtained. The external diameter of the nanotubes was 100–300 nm, the internal cavity 20–100 nm, and the length extended to several micrometres. The morphology of PANI, granular or tubular, depends on the acidity conditions during the reaction rather than on the chemical nature of the acid. PANI nanotubes were also produced when aniline was oxidized in the absence of any acid. The bulk conductivity of PANI prepared in solutions of acetic acid was 0.08–0.27 S cm−1, depending on the acid concentration. Protonated PANI prepared in sulfuric and acetic acids were deprotonated with ammonium hydroxide to obtain PANI bases and the ammonium salt of the protonating acid. FTIR spectroscopy showed the differences in the molecular structure of the PANI bases. Irrespective of whether the polymerization was performed in solutions of sulfuric or acetic acid, PANI had hydrogen sulfate counter-ions only. The PANI morphology is thus not controlled by the nature of counter-ions. The acidity of the reaction medium determines the protonation of monomer, oligomer and polymer species. The chemistry of aniline oxidation is likely to be affected especially by the protonation of an intermediate in the pernigraniline form. It is proposed that, in the course of aniline oxidation, pH-dependent self-assembly of aniline oligomers predetermines the final PANI morphology. Copyright © 2005 Society of Chemical Industry
273 citations
TL;DR: In two-stage treatment, the composition and digestibility data indicate that the lignin content in the biomass is one of the major factors controlling the enzymatic digestibility.
202 citations
TL;DR: In this paper, the electrical conductivity of polyaniline film was studied by a four-point probe method at room temperature, and the influence of concentration of acid during polymerization of aniline and dopant concentration on the gas sensing characteristics of PANI film were reported.
Abstract: Polyaniline (PANI) was synthesized by oxidative polymerization of aniline using ammonium persulfate in an acid medium. The polyaniline salt was converted to base form by treatment with ammonium hydroxide. The polyaniline base was dissolved in N-methyl pyrrolidone (NMP) for film casting. The cast film was doped with HCl for obtaining higher conductivity. Both doped and undoped PANI films were characterized by UV-visible, FTIR, and XRD analyses. The electrical conductivity of the PANI film was studied by a four-point probe method at room temperature. Finally, ammonia gas-sensing characteristics of the prepared polyaniline film were studied by measuring the change in electrical conductivity on exposure to ammonia gas at different concentrations. The influence of concentration of acid during polymerization of aniline and dopant concentration on the gas sensing characteristics of PANI film are reported in this paper.
115 citations
TL;DR: In this article, the progress of polymerization and the PANI-film formation were monitored in situ by Fourier transform infrared spectroscopy after depositing a droplet of the reaction mixture on a ZnSe crystal.
107 citations
TL;DR: In this article, a simple determination method for halogens (Cl, Br, and I) in plant samples using inductively coupled plasma-mass spectrometry (ICP-MS) was developed.
88 citations
TL;DR: The FTIR spectra of ammonium salts collected after deprotonation proved that the counter-ions of the sulfate type, resulting from the decomposition of peroxydisulfate, always participated in the protonation of PANI as mentioned in this paper.
77 citations
TL;DR: In this paper, it was shown that zirconia synthesized by precipitation of Zirconyl chloride with NaOH leads to a ZIRconia with high surface area (224m 2 /g), which is relatively stable after high temperature exposure.
Abstract: The results presented in this work clearly show that zirconia synthesized by precipitation of zirconyl chloride with NaOH leads to a zirconia with high surface area (224 m 2 /g), which is relatively stable after high temperature exposure. Pd supported on this high surface area zirconia exhibit higher turnover frequency for methane combustion than when supported on zirconia obtained from zirconyl chloride precipitated with ammonium hydroxide. We also found that when the commercial zirconium hydroxide is subjected to a NaOH reflux treatment, we obtained a zirconia of high and stable surface area (157 m 2 /g) even after heating it at 700 °C. Pd supported on the Na treated commercially derived support shows the highest dispersion and the highest intrinsic activity than on any of the other preparations studied. The results presented in this paper open up a new venue for obtaining high surface area zirconia using the commercially available hydroxide. This work shows that it is possible to stabilize zirconia using a Na treatment and also obtain high catalytic activity for methane oxidation on Pd stabilized on such support. Kinetic results and the corresponding mechanistic interpretation and the IR results support that the effect is consistent with increasing water support interactions which in term affect the reaction kinetics.
46 citations
TL;DR: In this paper, the adsorption of gold on activated carbon in ammoniacal thiosulfate solution was studied, and it was found that the rate of initial adaption rate was fast, when compared to that of the overall adsaption process.
Abstract: The adsorption of gold on activated carbon in ammoniacal thiosulfate solution was studied. The variables affecting the adsorption of gold on the carbon included, among others, temperature, concentrations of ammonium hydroxide and thiosulfate, and those of accompanying cations and anions. The apparent activation energy for the adsorption process was estimated to be 19.4 kJ/mol, and this value indicates that the gold adsorption is film diffusion-controlled. It was also found that the rate of initial adsorption rate was fast, when compared to that of the overall adsorption process.
44 citations
TL;DR: In this paper, a simple co-precipitation technique has been used successfully for the preparation of pure, ultrafine, single phase BiNbO4 (BN), MgTiO3 and Mg4Ta2O9.
39 citations
TL;DR: In this article, a rotating disk electrode was used to study the oxygen reduction reaction (ORR) with ammonium and showed that the ORR rate was reduced by more than a factor of 10 on pre-reduced Pt and by 2.5 on preoxidised Pt.
37 citations
TL;DR: In this article, aqueous solution of zinc oxide and hexamethylenetetetramine (HMT) was used to form ZnO nanoparticles with diameters ranging from 15-33-nm to 25-43-nm.
Abstract: Crystalline zinc oxide nanoparticles have been prepared by mixing aqueous solutions of zinc nitrate and hexamethylenetetramine (HMT) at 60°C and 80°C. Transmission electron microscopy and X-ray diffraction show that the ZnO nanoparticles of diameters ranging from 15–33 nm and 25–43 nm long are formed. Aspect ratio is observed to range from 1.18 to 1.74 at 60°C and 1.22 to 1.70 at 80°C as the HMT to zinc nitrate concentration ratio increases from 10 to 150. Nanoparticle size decreases as the concentration of HMT increases. Much larger ZnO particles are formed with ammonium hydroxide as a hydrolysis agent without HMT. In summary, HMT is an ammonium-hydroxide source in the reaction, a surfactant for retaining nanosize, and not necessarily a template for ZnO nucleation.
TL;DR: In this article, a new inorganic-organic hybrid precursors for corrosion protective coatings on galvanized iron were prepared by adding 3-glycidyloxypropyltrimethoxysilane (GPS) to an aqueous nanosized boehmite solution.
Abstract: New inorganic–organic hybrid precursors for corrosion protective coatings on galvanized iron were prepared by adding 3-glycidyloxypropyltrimethoxysilane (GPS) to an aqueous nanosized boehmite solution. Transparent boehmite (AlOOH) sols were prepared at 100 °C by peptizing aluminum hydroxide cake, which was obtained from the reaction between aqueous aluminum chloride and aqueous ammonium hydroxide solution (pH 8). Three different types of precursor sols, such as pure boehmite, hydrolyzed GPS, and boehmite–GPS hybrid sols were prepared and they were deposited on ultrasonically cleaned galvanized iron plates by using dip coating technique at room temperature. All the coatings were cured at 100–180 °C for 0.5–5 h in air, and their anticorrosion behavior was studied by analyzing the potentiodynamic polarization curves at room temperature. It was observed that the coatings cured at 150 °C for 3 h with GPS to boehmite molar ratio=0.7 exhibited the maximum corrosion resistance property, which attributed to the formation of a dense microstructure by cross-linking of functionalized nanoparticles.
TL;DR: In this article, the growth rate and optical properties of CdS thin films prepared by the chemical bath deposition technique were investigated, and the growth kinetics were relatively fast when the quantity of thiourea is increased in the deposition solution and higher value of band gap was obtained.
TL;DR: In this article, aldol-type condensation of aldehydes with ethyl diazoacetate (EDA) promoted by an organic base and non-metallic catalyst such as tetrabutylammonium hydroxide (TBAOH) gave β-hydroxy-α-diazocarbonyl compounds with moderate to excellent yields.
Patent•
21 Nov 2006TL;DR: In this paper, a method of removing materials selected from the group consisting of photoresist, ion implanted photoresists, etch residue, BARC and combinations thereof, from a substrate comprising: applying a formulation, described above, to the substrate to remove the material from the substrate.
Abstract: A formulation for removing photoresist, ion implanted photoresist, etch residue or BARC comprises: an ammonium hydroxide and a 2-aminobenzothiazole, remainder water. Preferably the formulation comprises: tetramethyl ammonium hydroxide, tolyltriazole, propylene glycol, 2-aminobenzothiazole, dipropylene glycol monomethyl ether, remainder water; more preferably: tetramethyl ammonium hydroxide 1-15 wt %, tolyltriazole 1-5 wt %, propylene glycol 5-15 wt %, 2-aminobenzothiazole 1-10 wt %; dipropylene glycol monomethyl ether 20-45 wt %, remainder water. The invention is also a method of removing materials selected from the group consisting of photoresist, etch residue, BARC and combinations thereof, from a substrate comprising: applying a formulation, described above, to the substrate to remove the material from the substrate.
TL;DR: In this paper, an ion exchange resin column of 20 mmφ and 735 mm height was used to clarify the recovery and purity of tetra-methyl ammonium hydroxide at each step.
Abstract: Tetra-methyl ammonium hydroxide is used in various electric and electronic parts production processes such as semiconductor, liquid crystal display and printed circuit board. The discharged amount of this chemical reaches about 2,500 ton/year from one factory in Japan. The waste liquor discharged from the liquid crystal display production contains 0.53wt% tetra-methyl ammonium hydroxide, 60 mg/dm3 phenol and ppb level of metal ions. In the cation exchange reaction, tetra-methyl ammonium ion is captured on the cation exchange resin. Other non-ionic organic matter like phenol goes through the resin without being captured on it, the separation being attained in this step. In the elution step, tetra-methyl ammonium ion captured on the resin is released as tetra-methyl ammonium chloride into aqueous solution by the action of dilute hydrochloric acid. Tetra-methyl ammonium chloride is converted to tetra-methyl ammonium hydroxide by the reaction between tetra-methyl ammonium chloride and OH− type anion exchange resin. The process is composed of three steps: cation exchange, elution and conversion. The experiments were carried out using ion exchange resin column of 20 mmφ and 735 mm height, in order to clarify the recovery and purity of tetra-methyl ammonium hydroxide at each step.
TL;DR: In this paper, a mixture of ammonium oxalate and ammonium hydroxide was used to co-precipitate calcium and niobium ions as calcined powders under basic conditions.
Patent•
04 Apr 2006TL;DR: In this article, a method for selectively etching metal-containing materials (such as, for example, metal nitrides) relative to one or more of silicon, silicon dioxide, silicon nitride, and doped silicon oxides in high aspect ratio structures with high etch rates was proposed.
Abstract: Various methods for selectively etching metal-containing materials (such as, for example, metal nitrides, which can include, for example, titanium nitride) relative to one or more of silicon, silicon dioxide, silicon nitride, and doped silicon oxides in high aspect ratio structures with high etch rates. The etching can utilize hydrogen peroxide in combination with ozone, ammonium hydroxide, tetra-methyl ammonium hydroxide, hydrochloric acid and/or a persulfate. The invention can also utilize ozone in combination with hydrogen peroxide, and/or in combination with one or more of ammonium hydroxide, tetra-methyl ammonium hydroxide and a persulfate. The invention can also utilize ozone, hydrogen peroxide and HCl, with or without persulfate. The invention can also utilize hydrogen peroxide and a phosphate, either alone, or in combination with a persulfate.
TL;DR: The influence of water on the observed gas-phase population of negative ions in electrospray mass spectrometry was studied for the undiluted ionic liquid 1,3-butyl-methyl-imidazolium hexafluorophosphate (BMIM+PF6−).
TL;DR: In this article, the influence of three different alkali reagents, i.e., ammonium hydroxide, sodium hydroxides and potassium hydroxite, on phase formation and crystallite morphology of lead titanate prepared under mild hydrothermal conditions was investigated.
Patent•
13 Jul 2006TL;DR: In this paper, a method for selectively etching metal-containing materials (such as, for example, metal nitrides) relative to one or more of silicon, silicon dioxide, silicon nitride, and doped silicon oxides in high aspect ratio structures with high etch rates was proposed.
Abstract: Various methods for selectively etching metal-containing materials (such as, for example, metal nitrides, which can include, for example, titanium nitride) relative to one or more of silicon, silicon dioxide, silicon nitride, and doped silicon oxides in high aspect ratio structures with high etch rates. The etching can utilize hydrogen peroxide in combination with ozone, ammonium hydroxide, tetra-methyl ammonium hydroxide, hydrochloric acid and/or a persulfate. The invention can also utilize ozone in combination with hydrogen peroxide, and/or in combination with one or more of ammonium hydroxide, tetra-methyl ammonium hydroxide and a persulfate. The invention can also utilize ozone, hydrogen peroxide and HCl, with or without persulfate. The invention can also utilize hydrogen peroxide and a phosphate, either alone, or in combination with a persulfate.
TL;DR: In this paper, the possibility of using sputtered metals as mask materials for deep anisotropic alkaline etching in silicon was investigated, and sputtered titanium was found to have excellent adhesion properties, but was susceptible to chemical attack under some conditions.
Abstract: The possibility of using sputtered metals as mask materials for deep anisotropic alkaline etching in silicon was investigated. Sputtered films of chrome, nickel and tungsten were all found to be chemically resistant to potassium hydroxide (KOH) and tetramethyl ammonium hydroxide (TMAOH). However, as expected, these metals had poor adhesion to silicon. By comparison, sputtered titanium was found to have excellent adhesion properties, but was susceptible to chemical attack under some conditions. Titanium was found to be chemically resistant to TMAOH if the solution was kept below 80 °C, and to KOH solution only below 80 °C and with the pH reduced by the addition of a weak acid. An alternative was to thermally oxidize the titanium, in which case it was chemically resistant to KOH and TMAOH under all conditions. However, TiO2 was found to be more difficult to pattern and remove than titanium.
TL;DR: A simple coprecipitation technique has been used successfully for the preparation of pure, ultrafine, single phases of NaNbO3 and NaTaO3 (NT) in this article.
Abstract: A simple coprecipitation technique has been used successfully for the preparation of pure, ultrafine, single phases of NaNbO3 (NN) and NaTaO3 (NT). An alcoholic solution of ammonium carbonate and ammonium hydroxide was used to precipitate Na+ and Nb5+ (or Ta5+) cations under basic conditions as carbonate and hydroxide, respectively. On heating at 700°C, these precursors produce respective products. For comparison, both NN and NT powders were also prepared by the traditional solid state method. The phase purity and lattice parameters were studied by powder X-ray diffraction (XRD). The particle size and morphology were studied by scanning electron microscopy (SEM).
TL;DR: A simple co-precipitation technique had been successfully applied for the preparation of pure ultrafine single phase BaBi 2 Ta 2 O 9 (BBT) in this article, where ammonium hydroxide and ammonium oxalate were used to precipitate Ba 2, Bi 3+ and Ta 5+ cations simultaneously.
TL;DR: In this paper, an aqueous mixture of ammonium oxalate and ammonium hydroxide was used to coprecipitate barium and strontium ions as oxalates and niobium ion as hydroxides under basic conditions.
Abstract: An aqueous mixture of ammonium oxalate and ammonium hydroxide was used to coprecipitate barium and strontium ions as oxalates and niobium ions as hydroxide under basic conditions. This precursor on calcining at 750°C yielded Sr0.5Ba0.5Nb2O6 phase. This is a much lower temperature than that prepared by traditional solid state method (1000°C) as reported for the formation of Sr0.5Ba0.5Nb206 (SBN). Transmission electron microscopic (TEM) investigations revealed that the average particle size was 80 nm for the calcined powders. The room temperature dielectric constant at 1 kHz was found to be 1100. The ferroelectric hysteresis loop parameters of these samples were also studied.
TL;DR: In this paper, the influence of the preparation method on the catalytic properties of lanthanum-doped hematite was studied and it was found that preparation method strongly affects the properties of the catalysts.
Abstract: The influence of the preparation method on the catalytic properties of lanthanum-doped hematite was studied in this work It was found that the preparation method strongly affects the properties of the catalysts The samples showed different particle sizes and specific surface areas as well as different resistance against reduction The most active catalyst in the ethylbenzene dehydrogenation was obtained by adding the iron and lanthanum nitrate solutions to an ammonium hydroxide solution This solid is also able to produce a low amount of coke and has the advantage of being non-active
TL;DR: In this article, a simple coprecipitation technique was used successfully to synthesize fine powders of MgNb{sub 2}O{sub 6} (MN) phase.
TL;DR: In this paper, the effects of ammonium hydroxide concentration and pH on the kinetics and reaction mechanism of oxidative ammonolysis of Repap organosolv lignin were studied.
Abstract: The effects of ammonium hydroxide concentration and pH on the kinetics and reaction mechanism of oxidative ammonolysis of Repap organosolv lignin were studied. The reactions were carried out at 100...
TL;DR: In this article, Nitrate was removed from the waste by passing through Dowex 1 × 4 anion exchange resin in OH− form and 1.0 M NaOH was used to regenerate the resin.
01 Jan 2006
TL;DR: In this article, the preparation, characterization and gas sensing properties of pure and Fe2O3-ZnO mixed oxide semiconductors have been investigated and the effects of microstructure and doping concentration on the gas response, selectivity, response and recovery of the sensor in the presence of NH3 gas were studied and discussed.
Abstract: The preparation, characterization and gas sensing properties of pure and Fe2O3-ZnO mixed oxide semiconductors have been investigated. The mixed oxides were obtained by mixing ZnO and Fe2O3 in the proportion 1:1, 1:0.5 and 0.5:1. Pure ZnO was observed to be insensitive to N H3 gas. However, mixed oxides (with ZnO: Fe2O3 =1:0.5) were observed to be highly sensitive to ammonia gas. Upon exposure to NH 3 gas, the barrier height of Fe 2O3-ZnO intergranular regions decreases markedly due to the chemical transformation of Fe2O3 into well conducting ferric ammonium hydroxide leading to a drastic decrease in resistance. The crucial gas response was found to NH 3 gas at 350 0 C and no cross response was observed to other hazardous and polluting gases. The effects of microstructure and doping concentration on the gas response, selectivity, response and recovery of the sensor in the presence of NH3 gas were studied and discussed.