Aqueous Solution Of Boric Acid Research Articles

Chemical modification of polymers to improve flame retardance—I. The influence of boron-containing groups

Samples of a linear polystyrene have been boronated, predominantly in the para-positions on the phenyl rings, by reaction first with mercuric tri-fluoroacetate and then with catechol borane, and the products then hydrolysed to give the polymeric boronic acids. Flame-retardant effects of these modifications have been assessed by measurements of limiting oxygen indices (LOI), and of weight losses and char yields on heating in air. The boron modified polymers have increased LOI values and give greater yields of char in comparison with those of the unmodified polystyrene. The surface modification of films of poly(vinyl alcohol) and of poly(ethylene-co-vinyl alcohol) with alkali metal borates has also given some encouraging results. Increases in LOI values and char yields can be optimised by adjusting the concentrations of the aqueous solutions of boric acid and sodium hydroxide used to effect the modifications.

Swelling/shrinking kinetics of chemically cross-linked poly(vinyl alcohol) gels in the presence of borate ions

The swelling/shrinking kinetics of chemically cross-linked poly(vinyl alcohol) (PVA) gels with borate ions has been studied by measuring the gel size as a function of time. The experimental process consisted of two steps, i.e., (I) immersion of a gel in a mixture of NaOH and boric acid aqueous solutions, and (II) subsequent immersion in deionized water or in a NaOH solution without borate ions. In step I, the gel swelled or shrank depending on the borate ion concentration and reached individual equilibrium values within 5000 min. After equilibration, the gel was transferred to the second bath and step II was initiated. When a gel was immersed in deionized water, the gel swelled considerably and then deswelled gradually to the original size. On the other hand, when a gel was dipped in a bath containing NaOH, a reverse process of step I took place and the gel size gradually reduced to the original size. The diffusion coefficients in these steps are discussed in conjunction with those obtained by dynamic light scattering.

Volumetric properties of aqueous electrolytes at high temperature. II. B(OH)3 and B(OH)3?NaB(OH)4?NaOH mixtures up to 523 K

The densities of boric acid aqueous solutions and sodium hydroxide-sodium borate mixtures were measured as a function of concentration, between 375 and 523 K at pressures close to saturation. The partial molar volumes of boric acid were obtained and it was found that they are almost independent of the concentration. The partial molar volumes of the sodium hydroxide-sodium borate mixtures were fitted to the Pitzer equation for mixtures using the known parameters for NaOH. Thus, the partial molar volume at infinite dilution and the Pitzer parameters of sodium borate could be obtained by assuming ideal mixing.

Volumes and heat capacities of H 3BO 3(aq) at temperatures from 298.15 K to 705 K and at pressures to 35 MPa

The densities and heat capacities of aqueous solutions of boric acid have been measured at temperatures from 298.15 K to 705 K and at pressures up to 35 MPa. The results are in reasonable agreement with the previous measurements at temperatures of 600 K and below. At temperatures and pressures in the neighborhood of the critical point of water, the results show the expected dependence of partial molar volume and partial molar heat capacity of H 3BO 3(aq) on temperature and density. The boric acid molecules have strong enough attractive interactions with water that the apparent molar volume and the apparent molar heat capacity of H 3BO 3(aq) show behavior with the same sign as of aqueous NaCl, although the magnitude is much less.

Effect of boric acid on the severity of vapor explosions in pure water and surfactant solutions

Four different dilute aqueous solutions of boric acid and surfactant/boric acid were tested to determine the impact of these coolant additives on the severity of vapor explosions in small-scale experiments with molten tin. Twelve grams of molten tin at 800°C were dropped into 6 l of coolant solution at room temperature; for each solution, the experiment was repeated 20 times. The coolants examined were pure water, 500 wppm boric acid solution, 2000 wppm boric acid solution, 5 wppm of a non-ionic surfactant (nonylphenol polyethylene glycol ether) in a 500 wppm boric acid solution, and 5 wppm of an ionic surfactant (dodecylbenzene sulfonate sodium salt) in a 500 wppm boric acid solution. Pressure and impulse data suggest that the presence of boric acid up to 2000 wppm concentration did not significantly affect the severity of the interactions. Particle size analysis, however, indicates that enhanced fragmentation took place at the higher concentration (2000 wppm). The data indicate that the presence of boric acid negates the potentially mitigating effects of the surfactant additives previously reported in experiments where the surfactants were added to pure water.

Enantioselective Distribution of Amino-Alcohols in a Liquid-Liquid Two-Phase System Containing Dialkyl L-Tartrate and Boric Acid.

Racemic amino-alcohols such as pindolol, propranolol, alprenolol and bucumolol enantiomers exhibited different distribution behaviors in a two-phase system consisting of a chloroform solution of didodecyl L-tartrate and an aqueous solution of boric acid. It seemed that a borate complex of the 1, 2-diol group of the tartrate and the amino-alcohol was formed in the system. In the case of pindolol, one enantiomer was preferentially extracted into the organic phase (×2.20) at equilibrium.

Repellency of Aqueous Solutions of Boric Acid and Polybor 3 to House Flies (Diptera: Muscidae)

Mixed-sex 3- to 5-d-old adult house flies, Musca domestica (L.), were exposed in nonchoice, choice, and consumption tests to increasing levels of boric acid and polybor formulated in 10% sucrose to test for repellent effects. Results of nonchoice and choice tests suggested repellency to high levels of both borates. Consumption decreased at levels >2.25% boric acid and 3.0% polybor, with approximate intake of 0.102 and 0.161 mg of boron, respectively. Our results indicate that 2.25% boric acid and 3.0% polybor are optimal treatment levels.

Thermodynamics of mixture of boric acid with lithium borate and chloride

AbstractThe first thermodynamic dissociation constants of boric acid in aqueous solution of lithium chloride with borate at five different temperatures from 278.15 to 318.15 K were evaluated from ernf values of the cell without liquid junction potential with the improved extrapolation and polynomial approximation on the basis of Pitzer's theory. Values obtained from both methods are in good agreement with each other. Pitzer's parameters β(0) and β(1) of LiB(OH)4 and other thermodynamic quantities of dissociation process of boric acid are obtained. Results have been discussed.

Compositional and thermal effects on chemically processed AlN–BN nanocomposite powders

Powders of nanocrystalline aluminum nitride (AlN) and boron nitride (BN) were prepared via a chemical route. Precomposite gels, which were obtained from ammonolysis of aqueous solutions of boric acid, urea, and aluminum chloride hexahydrate, were thermally processed to produce AlN-BN nanocomposite powders with a wide range of compositions. These powders were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The structure, morphology, and crystallite size of the powders are correlated with the compositions and processing temperature. Normal and abnormal grain growth are discussed.

Effect of the substitution of boron for aluminium in the β-eucryptite LiAlSiO4 structure

Abstract The substitution of B for Al in the β-eucryptite structure was examined along the compositional series described by the stoichiometry LiAl (1− x ) B x SiO 4 with x ranging from 0 to 1. These samples were prepared according to a sol-gel route which employs prehydrolysed tetraethylorthosilicate (TEOS), Al and Li nitrates and boric acid in aqueous solution. Two different monophasic fields were found with the β-eucryptite and the β-spodumene structure, respectively, with 0 ≤ x ≤ 0.40 and 0.60 ≤ x ≤ 0.80; their relative stability is discussed in terms of averaged ionic radius of B, Al and Si ions and of lithium content.

Solubility of boric acid in aqueous solutions of chloride salts

Solubility of boric acid in aqueous solutions of sodium chloride, potassium chloride and of both sodium and potassium chlorides was measured in a wide range of salt concentrations at temperatures from 303–373 K. These data, together with solubility data of chloride salts in aqueous solutions of boric acid, are used to parameterize a general thermodynamic model which uses the Wilson equation, along with contributions from Debye-Huckel and a Born term, in order to express the activity coefficients. The model, which contains only binary interaction parameters, can be used to correlate and predict thermodynamic properties of multicomponent aqueous systems containing boric acid along with both sodium and potassium chlorides.

Solubility of boric acid in aqueous solutions of sulfate salts

Solubility of boric acid in aqueous solutions of sodium sulfate, potassium sulfate and of both sodium and potassium sulfates and solubility of sulfate salts in aqueous solutions of boric acid were measured in a wide range of salt concentrations at temperatures from 303–373 K. The experimental data have been correlated by a thermodynamic model which uses the Wilson equation along with contributions from Debye-Huckel and a Born term in order to express the activity coefficients. The predictive capability of this model, which contains only binary interaction parameters, has been verified on multicomponent systems in the whole range of the process operating conditions.

Comparative Toxicity of Aqueous Solutions of Boric Acid and Polybor 3 to House Flies (Diptera: Muscidae)

LC50s and LT50s of boric acid and polybor formulated in water and 10% sucrose were determined for 3- to 5-d-old adult house flies, Musca domestica (L.), of mixed sex. Differences between boric acid and polybor toxicities were significant in 10% sucrose, but not in water. However, borates formulated in water had significantly lower LC50s than those formulated in 10% sucrose. Rate of kill for formulations in water was fairly uniform over time, whereas mortality from sucrose formulations was not observed until 17 h after treatment. Reasons for differences in the manifestation of mortality and possibilities for practical application are discussed.

ホウ酸水溶液中におけるα‐Ｄ‐グルコースの変旋光

ホウ酸水溶液にα-D-グルコースを添加すると,溶液の電気伝導度がいったん著しく増大し,その後経時的に低下することを認め,これをα-D-グルコースが変旋光によってβ-D-グルコースになり,αホウ酸との錯体形成能が低下することによると説明した。このホウ酸水溶液中におけるα-D-グルコースの変旋光速度を測定し,この速度は一定の飴翫グルコ-ス濃度において,ホウ酸濃度の増加にしたがっていったん増加し,その後極大を経て減少することを認めた。この変旋光速度のホウ酸濃度依存性について,1)ホウ酸はα一D一グルコースのみと錯体を形成する,2)α つ一グルコースとホウ酸との問の錯体形成によって生じたオキソニウムイオソの触媒作用によってα-D-グルコースの変旋光が促進される,および3)錯体を形成したα-D-グルコースは変旋光を行わない,という仮定を置いて変旋光速度を表す理論式を導いた。この理論式による変旋光速度の算出値と実測値を比較し,この理論式がホウ酸水溶液中におけるα-D-グルコースの変旋光速度を近似的に表現していることを確認し,前述の仮定がほぼ正しいものと結論した。

High Field11B and13C Nmr Investigations of Aqueous Borate Solutions and Borate-Diol Complexes

Abstract 11B nuclear magnetic resonance spectra of concentrated aqueous solutions of boric acid and the tetrahydroxyborate B[OH]- 4 ion, or of borax, Na2B4O7, at 128.4 MHz, reveal substantial amounts of triborate species in the pH range 8–10.5 and enable equilibria such as B3O3(OH)4 - + OH- α B3O3(OH)5 -2 and the hydrolytic dissociation of these ions to be studied. Addition of the polyhydroxy-compounds ethane-1,2-diol, propane-1,2-diol, propane- 1,3-diol and glycerol results in the formation of a variety of mono- and bis-chelated complexes, among which are spirocyclic anions with five- and six-membered rings sharing a common boron atom. Complexes in which boron atoms of triborate anions are coordinated by diol ligands are also identified. 11B chemical shifts characteristic of chelated and hydroxylic boron centres in mono- and triborate species are reported, taking into account the trends accompanying a change from trigonal to tetrahedral coordination. 1H and 13C NMR spectra of borale solutions containing ...

Thermodynamics of aqueous solutions of boric acid

Vapor pressures of aqueous solutions of boric acid over a wide range of acid concentrations were measured from 40 to 100°C. The results, together with solubility data taken from the literature, can be described with a thermodynamic model which uses the Wilson equations to express the activity coefficients of water and boric acid. Only three temperature independent adjustable parameters are required; one of these represents the entropy of fusion of boric acid, data which are not available in the literature.

Gradient-index glass rods of PbOK 2OB 2O 3SiO 2 system prepared by the sol-gel process

A glass rod of the PbOK 2OB 2O 3SiO 2 system having a radial gradient of refractive index has been prepared by the sol-gel process using aqueous solutions of lead acetate and potassium nitrate as the sources for index-modifying cations. A gel prepared by gelatinizing a sol from the mixture of tetramethoxysilane, tetraethoxysilane, and the aqueous solutions of boric acid and lead acetate was placed in an aqueous solution of potassium nitrate to form the concentration gradient of modifier cations by diffusion through the micropores of the gel. The glass rod of about 7 mm in diameter obtained by drying and sintering the gel had a refractive index of parabolic profile changing from the center toward the perimeter with a maximum difference of about 0.04.

イリジウム酸化物で被覆した白金極の酸素電極の挙動

Iridium oxide-coated platinum was prepared on the idea that coating of a tetravalent iridium cation will increase the amount of adsorbed oxygen on a Pt electrode because Ir4+ has large electron accepting property. The reversible potential of oxygen electrode reaction has been established on the iridium oxide-coated platinum in dilute aqueous boric acid solutions and observed about one year. The value of the exchange current density is ten times as much as the most active values reported in the literature. XPS observation confirmed that the surface Jr species was IrO2.

Reactivity of the hydrated electron and the hydroxyl radical with boric acid in aqueous solutions

The reactivity of the hydrated electron and the hydroxyl radical with boric acid has been investigated by steady-state and pulse radiolytic techniques. No evidence was found for appreciable reactivity with hydroxyl radicals by either method and an upper limit of 5 × 10 4 dm 3 mol -1 s -1 is estimated for the reaction rate constant. Steady-state irradiations gave no evidence for reactivity with the hydrated electron, but pulse-radiolysis experiments showed the hydrated electron decay rate to be linearly dependent on boric acid concentration but independent of pH. Although superficially suggesting a reaction with boric acid it seems more likely that the enhanced decay is due to an impurity in the boric acid (probably nitrate) and an upper limit of 5 × 10 3 dm 3 mol -1 s -1 is estimated for k(e - aq + H 3BO 3).

Studies of activated charcoal cloth. II. Influence of boron-containing impregnants on the rate of activation in carbon dioxide gas

The influence of aqueous solutions of boron-containing compounds as impregnants of viscose rayon cloths on the subsequent activation of the derived carbonised materials in CO 2 gas at 850°C has been studied. The presence of Na + (or other alkali metal ions) is essential for the enhancement of the rate of activation above that observed for the untreated cloth or for the cloth initially impregnated with aqueous boric acid solutions. However, in terms of the activation rate generated, borax is more effective as an additive to boric acid solutions than sodium chloride. The results are interpreted in terms of the catalytic abilities of various alkali metal ions in the systems studied and the complexity of the borate species generated at different pH values in the aqueous impregnant solutions employed.