Mechanical properties,thermal stability,sound absorption,and flame retardancy of rigid PU foam composites containing a fire‐retarding agent: Effect of magnesium hydroxide and aluminum hydroxide

Isocyanate, polyether polyol, a flame retardant (10 wt%), and aluminum hydroxide/magnesium hydroxide (0, 5, 10, 15, and 20 wt%) are used to form the rigid polyurethane (PU) foam, while nylon nonwoven fabrics and a polyester aluminum foil are combined to serve as the panel. The rigid PU foam and panel are combined to form the rigid foam composites. The cell structure, compressive stress, combustion resistance, thermal stability, sound absorption, and electromagnetic interference shielding effectiveness (EMI SE) of the rigid foam composites are evaluated, examining the effects of using aluminum hydroxide and magnesium hydroxide. Compared with magnesium hydroxide, aluminum hydroxide exhibits superior performance to the rigid foam composites. When aluminum hydroxide is 20 wt%, the rigid foam composite has an optimal density of 0.153 g/cm³, an average cell size of 0.2466 mm, a maximum compressive stress of 546.44 Kpa, an optimal limiting oxygen index (LOI) of 29.5%, an optimal EMI SE of 40 dB, and excellent thermal stability and sound absorption.     

Simultaneous determination of seven trace impurities (Al, As, Cr, Fe, Ti, V and Zr) in high-purity nickel metal and nickel oxide by coprecipitation and inductively coupled plasma-atomic emission spectrometry

Nickel is not coprecipitated with lanthanum hydroxide in ammonium hydroxide solution because it forms rapidly soluble nickel ammine complexes. This behaviour is used for the separation of Ni matrix from trace elements. These are simultaneously and quantitatively coprecipitated with lanthanum hydroxide at pH 10.0 and separated from the Ni matrix. Seven trace elements (Al, As, Cr, Fe, Ti, V and Zr) in Ni metal and 3 certified elements (Cr, Fe and Ti) in a standard reference material of nickel oxide have been simultaneously determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES).     

Vibrational spectra, structure, and proton conduction in hydrous tin dioxide

SnO₂ · nH₂O (hydrous tin dioxide, HTD, n = 1.5) and SnO₂ · nD₂O (deuterated hydrous tin dioxide, DHTD) samples were studied by IR and Raman spectroscopy. The using of these spectroscopic methods elucidated some structural features of the hydrogen-bond network in HTD, where two types of water molecules and two types of hydroxide groups are present. Type 1 water molecules and hydroxide groups are found to be linked to one another by weak hydrogen bonds, as in liquid water. Type 2 water molecules and hydroxide groups are linked to type 1 water molecules and hydroxide groups by rather strong hydrogen bonds. The existence of these strong hydrogen bonds is interpreted as arising from the effect of tin ions on some water molecules and hydroxide groups. Proton conductivity in HTD was found by the impedance method to be a nearly linear function of n. The break of the line at n = 1.3 corresponds to the percolation threshold. The roles of type 1 and type 2 water molecules and hydroxide groups in the generation of proton conduction in HTD are discussed.     

Ribbon- and boardlike nanostructures of nickel hydroxide: synthesis, characterization, and electrochemical properties

We report the synthesis, characterization, and electrochemistry properties of ribbon- and boardlike nanostructures of nickel hydroxide, which crystallize in different phases. The ribbonlike nanostructures (nanoribbons) of nickel hydroxide were synthesized by treating amorphous alpha-Ni(OH)2 with high concentrations of nickel sulfate. These nanoribbons crystallized in a new phase had typical widths of 5-25 nm, thicknesses of 3-9 nm, and lengths of up to a few micrometers. After further treatment in alkali at 60 degrees C, the nanoribbons converted to boardlike nanostructures (nanoboards), which crystallized in the beta-phase with the average length-width-thickness ratio of 20:6:1. The crystal structures, Raman spectra, and electrochemical properties of these nanostructures of nickel hydroxide are described in this paper. For comparison, the amorphous alpha-Ni(OH)2 has also been investigated. Moreover, the intermediate product between the nanoribbons and the nanoboards displays a unique structure, which implied an interesting transformation process. The nanoribbons with the new phase show some unique features in Raman spectra, two new peaks located at 3534 and 3592 cm(-1) in the OH stretching region, indicating the new chemical environment of the hydroxyl groups. The nanoboards exhibit the highest specific capacity, which is close to the theoretical capacity of beta-Ni(OH)2. It suggests that the boardlike nanostructure is helpful in improving the electrochemical performance of nickel hydroxide. Because of their unique structures and properties, the nanoribbons and nanoboards of nickel hydroxide may give a new perspective for applications in the areas of catalysts and rechargeable batteries.     

The use of ammonium hydroxide as an additive in supercritical fluid chromatography for achiral and chiral separations and purifications of small, basic medicinal molecules

This study describes using 0.1% of a 28-30% ammonium hydroxide solution as an additive to alcohol modifiers in SFC to improve chromatographic peak shapes for basic molecules. Ammonium hydroxide's high volatility leaves no residual additive in the purified sample unlike classical additives in preparative chromatography such as diethylamine and triethylamine. We demonstrate that the silica support is stable despite having ammonium hydroxide in the modifier by running a durability study for over 350 h (105 L of solvent, 105,000 column volumes) on an analytical Chiralcel OJ column and a second study for 30 h (7.2 L, 14,400 column volumes) on an analytical Lux Cellulose-1 column. The peak shape of small, basic molecules is greatly improved with the use of ammonium hydroxide and this improvement is very similar to those having 0.1% diethylamine as a mobile phase additive. Electrospray ionization is also enhanced with the presence of ammonium hydroxide compared with that of diethylamine. We have found that the age of the 28-30% bottle of ammonium hydroxide solution can have significant effects on the chromatography and we describe how this can be overcome. Finally, we analyzed 23 racemic and basic compounds on six different chiral stationary phases and found there to be very little chiral selectivity difference between ammonium hydroxide and diethylamine, triethylamine, ethanolamine and isopropylamine.     

Synthesis, characterization, and X-ray crystal structure of a gallium monohydroxide and a hetero-bimetallic gallium zirconium oxide

A monomeric hydroxide of gallium, LGa(Me)OH, containing terminal hydroxide and methyl groups was prepared by the hydrolysis of LGa(Me)Cl in the presence of N-heterocyclic carbene and water [L = HC{(CMe)(2,6-i-Pr2C6H3N)}2] in high yield and in a pure form. LGa(Me)OH was used as a synthon to assemble the first hetero-bimetallic compound with a Ga-O-Zr core, [(LGaMe)(Cp2ZrMe)](mu-O).     

Hydration, swelling, interlayer structure, and hydrogen bonding in organolayered double hydroxides: insights from molecular dynamics simulation of citrate-intercalated hydrotalcite

Molecular dynamics (MD) simulation of the Mg/Al (3:1) layered double hydroxide (LDH), hydrotalcite (HT), containing citrate, C6H5O7(3-), as the charge balancing interlayer anion provides new molecular scale insight into the interlayer structure, hydrogen bonding, and energetics of the hydration and consequent swelling of LDH compounds containing organic and biomolecules. Citrate-HT exhibits affinity for water up to very high hydration levels, in contrast to the preferred low hydration states of most LDHs intercalated with small, inorganic anions. This result is consistent with the recent experimental observation of the delamination of lactate-HT. The high water affinity is rationalized in terms of the preference of citrate ion for hydrogen bonds (H-bonds) donated from water molecules rather than from the hydroxyl groups of the metal hydroxide layer and the need to develop an integrated interlayer H-bond network among the citrate ions, water, and -OH groups of the hydroxide layers. The changes in the orientation of citrate molecules with progressive hydration are also intimately related to its preference to accept hydrogen bonds from water.     

Speciation of phenyltin(IV) compounds using high‐performance liquid chromatography: Part 1. The direct analysis of mixed standard solutions of tetraphenyltin,triphenyltin chloride,triphenyltin hydroxide and triphenyltin acetate

A rapid speciation high‐performance liquid chromatography (HPLC) method has been developed for the simultaneous determination of phenyltin compounds. The commercially important products of triphenyltin‐chloride, ‐acetate, ‐hydroxide and tetraphenyltin were separated by reversed‐phase HPLC on a Waters Spherisorb S5W ODS‐2 (octadecylsilica) column using an isocratic mixture of 90:10 (v/v) acetonitrile:water as the mobile phase at a flow rate of 1 ml min^?1. The phenyltin compounds were detected by UV detection at 254 nm and the total elution time is 8 min. The elution order is triphenyltin‐chloride, ‐acetate, ‐hydroxide and tetraphenyltin. Detection limits were 0.01 ppm for each of the triphenyltin compounds and 0.02 ppm for tetraphenyltin. Spiked water samples containing the three biocidal triphenyltin compounds could also be analysed simultaneously by the above method without the need for any prior derivatization, following extraction with toluene. The versatility of the method in sensing substituent group variations on the phenyl ring was also demonstrated by the successful resolution of the hydroxides, tris(p‐chlorophenyl)tin hydroxide, diphenyl(p‐chlorophenyl)tin hydroxide and triphenyltin hydroxide. Copyright © 2002 John Wiley & Sons, Ltd.     

Nucleophilic substitution by a hydroxide ion at a vinylic carbon: ab initio and density functional theory studies on methoxyethene, 3-methoxypropenal, 2,3-dihydro-4H-pyran-4-one, and 4H-pyran-4-one.

Nucleophilic substitutions by a hydroxide ion at vinylic carbons of methoxyethene (system A), 3-methoxypropenal (system B), 2,3-dihydro-4H-pyran-4-one (system C), and 4H-pyran-4-one (system D) were calculated by Becke's three-parameter hybrid density functional-HF method with the Lee-Yang-Parr correlation functional (B3LYP//B3LYP) and the second-order M?ller-Plesset theory (MP2//B3LYP) using the 6-31+G(d) and AUG-cc-pVTZ basis sets. In addition, bulk solvent effects (aqueous solution) were estimated by the polarized continuum (overlapping spheres) model (PCM-B3LYP//B3LYP) and the polarizable conductor PCM model (CosmoPCM-B3LYP//B3LYP). The mechanisms as well as the influence of resonance, cyclic strain, aromatic, and polar effects on the reactivity of the calculated systems were determined. In the gas phase the rate-determining step of nucleophilic vinylic substitutions by a hydroxide ion may be either addition of hydroxide ion at the vinylic carbon (systems A and B) or elimination of the leaving group (systems C and D). In aqueous solution, for all four systems investigated, addition of hydroxide ion at the vinylic carbon is rate determining.     

Facile Synthesis,Characterization, and Catalytic Behavior of a Large‐Pore Zeolite with the IWV Framework

Large‐pore microporous materials are of great interest to process bulky hydrocarbon and biomass‐derived molecules. ITQ‐27 (IWV) has a two‐dimensional pore system bounded by 12‐membered rings (MRs) that lead to internal cross‐sections containing 14 MRs. Investigations into the catalytic behavior of aluminosilicate (zeolite) materials with this framework structure have been limited until now due to barriers in synthesis. The facile synthesis of aluminosilicate IWV in both hydroxide and fluoride media is reported herein using simple, diquaternary organic structure‐directing agents (OSDAs) that are based on tetramethylimidazole. In hydroxide media, a zeolite product with Si/Al=14.8–23.2 is obtained, while in fluoride media an aluminosilicate product with Si/Al up to 82 is synthesized. The material produced in hydroxide media is tested for the hydroisomerization of n‐hexane, and results from this test reaction suggest that the effective pore size of zeolites with the IWV framework structure is similar to but slightly larger than that of ZSM‐12 (MTW), in fairly good agreement with crystallographic data.     

Rapid screening and confirmation of amphetamine, methamphetamine, methadone, and methadone metabolite in urine by gas/thin layer chromatography.

A method suitable for large scale screening and confirmation of urine speciments for amphetamine, methamphetamine, methadone, and its primary metabolite (2-ethylidene-1,5-dimethyl-3,3-diphenlypyrrolidine) is described. The drugs are extracted from alkaline urine into an organic solvent. The amphetamine drugs are then back-extracted into a small volume of acid and identified by gas chromatography both as free bases on a 10% Apiezon L-10% KOH column and as their trifluoracetamide derivatives on a 3% OV-17 column. The organic layer, which still contains methadone and its primary metabolite, is analyzed by split-sample thin-layer chromatography using two solvent systems: ethyl acetate: methylene cloride: concentrated ammonium hydroxide (90:10:0.7) and methanol: chloroform: concentrated ammonium hydroxide (74:25:0.8). These solvent systems separate methadone from its primary metabolite without interference from other drugs or urinary substances.     

Comparison of the base catalytic activity of MgO prepared by thermal decomposition of hydroxide,basic carbonate,and oxalate under atmospheric conditions

Research on Chemical Intermediates - To obtain highly active solid base catalyst of magnesium oxide (MgO) under atmospheric conditions, hydroxide (Mg(OH)2), basic carbonate...     

Electrophoretic analysis of amines using reversed-phase,reversed-polarity,head-column field-amplified sample stacking and laser-induced fluorescence detection

This paper describes the use of reversed-phase, reversed-polarity head-column field-amplified sample stacking (HCFASS) for on-line sample concentration in conventional capillary electrophoresis. The effective stacking efficiency was determined as a function of sodium hydroxide concentration in the sample matrix. Results concur with theoretical predictions where stacking efficiency depends on the conductivity (electric field strength) and electrophoretic mobility in the sample matrix solution. Fluorescein isothiocyanate-derivatized aniline and 2,4-dimethylaniline were dissolved in sodium hydroxide (800 microM), separated in a phosphate running buffer (0.05 M, pH 9.0) and detected utilising laser-induced fluorescence. The use of reversed-phase, reversed-polarity HCFASS with laser-induced fluorescence detection yielded sensitivity improvements with respect to normal injection schemes in excess of three orders of magnitude, and a limit of detection as low as 10(-13) M.     

Generation and Applications of the Hydroxide Trihydrate Anion, [OH(OH2)3]−, Stabilized by a Weakly Coordinating Cation

The reaction of a strongly basic phosphazene (Schwesinger base) with water afforded the corresponding metastable hydroxide trihydrate [OH(OH₂)₃]^? salt. This is the first hydroxide solvate that is not in contact with a cation and furthermore one of rare known water‐stabilized hydroxide anions. Thermolysis in vacuum results in the decomposition of the hydroxide salt and quantitative liberation of the free phosphazene base. This approach was used to synthesize the Schwesinger base from its hydrochloride salt after anion exchange in excellent yields of over 97 %. This deprotonation method can also be used for the phosphazene‐base‐catalyzed preparation of the Ruppert–Prakash reagent Me₃SiCF₃ using fluoroform (HCF₃) as the trifluoromethyl building block and sodium hydroxide as the formal deprotonation agent.     

Solid eutectics and crystalline hydrates of alkali hydroxides as proton-conducting electrolytes in cells with electrodes of graphite,silicon, and tin

Chemically and structurally complex forms of lithium, sodium, and potassium hydroxides (eutectics and crystalline hydrates) made up a new family of inorganic protonics with high conductivity in the range of 250–450 K. The electromotive force and voltammetric characteristics of solid-phase electrochemical cells on their basis point to the possibility of formation of small chemical power sources, e.g., for power supply of microelectronic devices. Therefore, extension of the scope of the studied electrolytes is supplemented by extension of the scope of electrodes capable of forming in contact with hydroxide electrolytes electrochemically active heterostructures. The capability of hydroxide protonics of operating in contact with the electrodes of group IV elements (Si, Sn, Pb) is observed for the first time.     

Potentiometric titration of fulvic acids from lignite, in dimethylformamide and dimethylsulphoxide media

Potentiometric titrations in dimethylformamide and dimethylsulphoxide have been performed in order to differentiate between the acidic groups of fulvic acids. With dimethylformamide as medium the best results have been obtained with potassium hydroxide as titrant, whereas both potassium hydroxide and tetrabutylammonium hydroxide yield good titrations in dimethylsulphoxide. The number of acidic groups differentiated depended on the solvent and titrant used; in the best case four sharp end-points were obtained. Titrations with potassium hydroxide are preferred.     

Ion chromatographic analysis of anions in ammonium hydroxide,hydrofluoric acid,and slurries,used in semiconductor processing

In this study, ion chromatography (IC) with suppressed conductivity detection was used for the determination of trace anions in 29% (w/w) ammonium hydroxide, 49% (w/w) hydrofluoric acid and slurries. For these samples, various sample pretreatment methods were applied to eliminate matrix interferences. For concentrated ammonium hydroxide, an on-line electrochemical neutralizer (SP10 AutoNeutralization module) was used to neutralize the base prior to the IC analysis. For concentrated hydrofluoric acid, a heart cutting technique with an ion-exclusion column was used to separate the anions of interest prior to an IC separation. A method was also developed to analyze chloride in silica slurries by IC.     

Synthesis,optimization, characterization,and potential agricultural application of polymer hydrogel composites based on cotton microfiber

The optimum content of cotton microfiber, initiator, cross-linker, and sodium hydroxide were determined using the central composite design method. Polymer hydrogels (PHGs) were characterized using Fourier-transform infrared (FT-IR), scanning electron microscopy, and thermal gravimetric analysis. A comparison between plain PHG and the polymer hydrogel composite (PHGC) in terms of biodegradation, swelling rate, and re-swelling capacity was carried out. The effect of PHGC on the sandy soil holding capacity, urea leaching loss rate (ULLR), and okra plant growth were evaluated. The highest water absorption capacity was obtained at 1.30 mass %, 0.15 mass %, 13.00 mass %, and 13.50 mass % of the initiator, cross-linker, sodium hydroxide, and cotton microfiber, respectively. Cotton microfiber has a prominent effect on the swelling rate, re-swelling capacity, and biodegradability of PHG. Okra plant growth and ULLR were positively affected by PHGC and the best leaching loss rate of 33.3 mass % was observed for the lowest urea loaded sample.     

Ellipsometry of nickel hydroxide electrodes formed by ex situ chemical precipitation. Potential routine and time effects

Ellipsometric and reflectivity data combined with voltammetric data have been obtained at 546.1 nm for different nickel hydroxide electrodes in 0.01 M NaOH at 25°C. The electrodes were prepared by ex situ chemical precipitation on a polished platinum substrate. The influence of the potential routine applied to the nickel hydroxide electrode on the corresponding optical parameters and time effects for both the oxidized and reduced forms of the active material kept at constant potential have been investigated. The nickel hydroxide layer is described as a mixture of nickel(II) hydroxide, nickel(III) hydroxide and electrolyte—water domains. The kinetic effects are discussed through a complex reaction pathway involving different nickel(II) and nickel(III) hydroxide species, the processes starting preferentially at the borders of the different domains.