Showing papers on "Aluminium hydroxide published in 1997"

Synthesis, Structure and Hydrolysis Studies of Dimethyltris(Trimethylsilyl)Methylmetallanes of Aluminium and Gallium†

Abstract: The reactions of [(Me3Si)3CLi2thf] with Me2MCl (M = Al, Ga) afford the mixed trialkylmetallanes [(Me3Si)3-CAlMe2·thf] (1) and [(Me3Si)3 CGaMe2·thf] (2) in high yields. The coordinated THF molecule of compound 2 can be removed by sublimation in vacuo to yield the solvent-free product [(Me3Si)3-CGaMe2] (3). Hydrolysis of compound 2 with one equivalent of water at 0°C gives the trimeric hydroxide [{(Me3Si)3CGaMe(μ-OH)}3] (4), while the reaction with two equivalents of water at room temperature yields the unusually stable gallium hydroxide-water complex [{(Me3Si)3CGaMe(OH)(μ-OH)MeGaC(SiMe3)3) H2O·2thf] (6). On heating, compound 6 is converted to the hydroxide [{(Me3Si)3C}4Ga4(μ-O)2(μ -OH)4] (5), which has a heteroadamantane-like core. The hydrolysis of compound 1 with one equivalent of water at − 25°C gives the dimeric hydroxide [{(Me3Si)3CAlMe(μ-OH)}2·2thf] (7), while the reaction with two equivalents of water results in the formation of the novel hydroxide [{(Me3Si)3C}4Al4(μ-O)2 (μ-OH)4] (8), which is isostructural to the gallium compound 6 with the adamantane-like structure. The molecular structures of compounds 1, 2, 4, 5·3THF, 6, 7 and 8·0.5 THF have been determined by X-ray structure analysis. Compound 7 is the first structurally characterised aluminium hydroxide containing methyl groups, and 8 is the smallest structurally characterised galloxane hydroxide described in literature.

Phosphinic acid aluminium salts

Abstract: The invention concerns aluminium salts of phosphinic acids or diphosphinic acids with alkyl and/or aryl substituents, obtained by heating an ester of the corresponding phosphinic acids or diphosphinic acids with aluminium hydroxide at a temperature of more than 150 °C under pressure in the presence of water. These salts are characterized by a particular crystal structure and are suitable as flame-proofing agents for plastics.

Monohydroxy aluminium oxide (Boehmite, AlOOH) as a reactive binder for extrusion of alumina ceramics

Abstract: Monohydroxy aluminium oxide (Boehmite, AlOOH) has been used as an extrusion aid along with α-alumina and γ-alumina particulates. Extended ball milling of the mixture using alumina grinding media imparts nucleating seeds to boehmite for an early conversion to α-alumina. The boehmite-γ-alumina mixture appears to result in a denser alumina ceramic accompanied by an enhanced grain growth indicating the higher reactivity at higher temperatures compared to the boehmite-α-alumina system. The reason for this novel behaviour is probably the coating of nanosize boehmite containing nucleating sites on the porous γ-alumina powders resulting in enhanced diffusion reactions. The present study therefore provides scope for low temperature alumina ceramics using boehmite binder along with partly dehydroxylated aluminium hydroxide.

Porous alumina as a support for catalysts and membranes. Preparation and study

Abstract: Porous alumina as single tubes and as a multihole structure with controlled properties has been prepared. It is shown that the porous structure of these supports can be controlled without burning out additives but by a variation of the ratio between the main alumina component (α-Al2O3) and aluminium hydroxide (binder) in the extrusion masses and thermal treatment conditions. Gas permeability measurements have been used for the characterization of the supports. The properties of the ceramics are shown to satisfy the requirements of membrane supports.

Intestinal absorption of trace amounts of aluminium in rats studied with 26aluminium and accelerator mass spectrometry

Abstract: 1. Until recently studies of intestinal aluminium absorption used pharmacological amounts of stable 27Al. 2. To examine the intestinal absorption of trace amounts of different chemical compounds of aluminium, in the present study we have employed the long half-life isotope of aluminium, 26Al, and accelerator mass spectrometry. Trace amounts of 26Al (2.7-12.1 ng) as the hydroxide, citrate, citrate plus 1 mmol/kg sodium citrate, or maltolate respectively, were administered to four groups of rats (n = 9 per group) by gavage. Blood and urine samples were collected for 5 h and the 26Al content (as a percentage of the administered dose) determined by accelerator mass spectrometry. 3. The 5 h urinary 26Al excretion amounted to 0.1 +/- 0.02, 0.7 +/- 0.2, 5.1 +/- 1.5 and 0.1 +/- 0.1% of administered dose in the four groups respectively. There was a strong positive correlation between peak plasma 26Al (r = 0.98) and urinary 26Al excretion in individual animals (P < 0.001). 4. We conclude that the fractional intestinal absorption of trace oral doses of aluminium hydroxide is at least 0.1% (compared with the previous estimate of 0.01% using large 27Al oral loads). Absorption of aluminium citrate given alone is significantly greater (0.7%) and is further increased to 5% by the accompanying sodium citrate, consistent with an enhancing effect of added citrate upon mucosal aluminium permeability. Aluminium maltolate absorption approximates that of aluminium hydroxide (0.1%).

Interactions between citrate and montmorillonite-Al hydroxide polymer systems.

Abstract: Summary Citrate forms strong complexes with A1 ions and may thus influence the stability and formation of Clay-A1 hydroxide polymer systems (CAIHO). We studied the adsorption of citrate to CAIHO and the influence of citrate on the stability and formation of CAIHO at different A1:clay and A1:citrate ratios and pH values and at a total salt concentration of 0·01 M monovalent anions. The amount of citrate sorbed to the aged CAIHO was independent of the A1 fixed to the clay as A1 hydroxide polymers (AIHO) at 5 < pH < 6·6. The added citrate seemed not to sorb to the AIHO but only to the edges of the clay. As the citrate: Al ratio increased from 15–1:l at pH 6, more of the AIHO of the aged CAMO systems dissolved. The change in the CEC of the clay indicated that the nature of the remaining AIHO is independent of the amount of A1 dissolved. Citrate influenced the formation of CAIHO systems as measured at pH 6·6, to an extent which depended on the citrate: Al ratio. At a small ratio (1:5), AIHO formed and all citrate was incorporated in the AIHO, probably leading to a coprecipitate. The amount of citrate incorporated depended linearly on the amount of AIHO present. Co-precipitation of AIHO and citrate probably led to the formation of a separate phase, which was only weakly bound to the clay particles. At a large citrate: Al ratio (1:1) soluble Al-citrate complexes became dominant, and only a small part of the added A1 was present as AIHO.

Value improvements of clays

Abstract: A process which allows the conversion of clay minerals of the kalonite group, to a relatively pure form of alumina and silica respectively comprising the steps of (a) heating the kaolinite group minerals to greater than 500° C., which causes dehydroxylation of the crystallographic lattice and formation of an intermediate meta-kaolin; (b) reacting the intermediate with only one of a selection of reagents including acids, alkalines or metalliferous compounds followed by heating of the mixture to form an aluminium salt in solution and residue of silica; (c) separation of the aluminium salt solution from the residue of silica by filtration and further treatment of the silica residue to produce a relatively pure form of fine particled silica; (d) formation of an alum by addition of ammonium sulphate in solution to the aluminium salt solution and further treatment of the alum to produce a relatively pure form of aluminium hydroxide.

Process for producing potassium sulfate and its by-product using potassium ore

Abstract: A process for producing potassium sulfate and its by-products from potassium ore comprises grinding potassium ore and lime stone, mixing, high-temp sintering, acidifying, settling, filtering, evaporating and crystallizing the supernatant to obtain potassium sulfate, and separating the settled sludge to obtain aluminium hydroxide, iron hydroxide, plaster stone and silicic acid.

Methods for producing corundum at low temperatures

Abstract: The goal of this study is to produce corundum at low temperatures, in order to eliminate sintering processes during its production. Two methods were used. One involved the production of an aluminium hydroxide sol made from aluminium alcoholate, that was then seeded with various amounts of hematite crystals (α-Fe 2 O 3 ). The development of the conversion temperatures to corundum and the achievable α-Al 2 O 3 amounts related to the seed crystal amount was examined. The method of seeding aluminium chlorohydrate with α-Al 2 O 3 crystals and the subsequent calcination of the powder at temperature of ca. 700°C proved to be the more promising way to produce finely dispersed corundum powder.

Expandable styrene polymers containing halogen-free flame retardants

Abstract: Expandable styrene polymer (EPS) particles (I) containing a volatile blowing agent (II) and at least 12 wt% fire retardant (III) consisting of a mixture of (A) a phosphorus compound and (B) a water-releasing metal hydroxide. Also claimed are (i) processes for the production of (I), (ii) a process for the production of polystyrene (PS) foam particles by foaming (I), and (iii) PS foam particles with a particle size of 2-10 mm and a density of 10-50 g/l, containing 12-30 wt% mixture (III). Preferably component (B) is magnesium or aluminium hydroxide, and (A) is red phosphorus or an organic or inorganic phosphate, phosphite or phosphonate, especially triphenyl phosphate, diphenyl cresyl phosphate, ammonium polyphosphate or diphenyl phosphate. Wt. ratio (B):(A) = (1:1)-(1:5). (I) contains 3-10 wt% (II), preferably a 4-6C aliphatic hydrocarbon.

Production of high purity silicon metal, aluminium, their alloys, silicon carbide and aluminium oxide from alkali alkaline earth alumino silicates

Abstract: The present invention concerns a procedure for production of high purity metals, their alloys and other species from feldspars and feldspar containing rocks. Silicon 'metal' (Si) and aluminium oxide (Al2O3) are produced by electrolysis. High purity Si produced from electrolysis is leached and refined by water which forms sodium hydroxide (NaOH), aluminium hydroxide (Al(OH)3) and hydrogen (H2). Si is then refined by using acids, and melted above 1410 °C. High purity silumin (AlSi alloys) is produced by alloying high purity Al and high purity Si from residual Si and Si(IV) in cryolite (Na3AlF6)/Al2O3 mixtures at about 970 °C. High purity silicon carbide (SiC) is produced by melting Si and adding cathodic and leached purified graphite (C) above 1410 °C.

Preparation of reforming platinum-rhenium catalyst

Abstract: Nitric acid in 0.1-5.0 wt% of aluminium hydroxide, acetic acid in 1.0-10.0 wt% and citric acid in 2.0-10.0 wt% are mixed and compounded into aqueous solution as peptizer, which is mixed with aluminium hydroxide powder containing 0.1-4.0 wt% sesbania powder. Then, the mixrure is kneaded, extruded, dried and roasted to obtain gamma-Al2O3 carrier strip, and Pt in 0.10-0.80 wt% of dry Al2O3, Re in 0.10-1.50 wt% and Cl in 0.5-2.0 wt% are loaded to produce the said catalyst. The said catalyst is suitable for use in the reforming of gasoline with distillation range of 60-210 deg.C produced through coking and cracking of naphtha or mixed oil.

Microstructure evolution in chelated partially hydrolysed alumina sols during sonogelling

Abstract: Optically transparent alumina sonogels with optical transmittance of over 90% have been prepared by chemically modifying a partially hydrolysed aluminium sec-butoxide precursor with ethyl acetoacetate. Chelating the alkoxide in a 1:2 molar ratio has permitted an enhanced control over microstructural changes during the sol to sonogel synthesis. Particle size and morphology changes during controlled sonogelling indicate that the sol to sonogel evolution in chelated alkoxides occurs by a dissolution-nucleation process in which the chelated species dissolves and aluminium hydroxide nucleates. The chelated agglomerates break down with increasing amount of water, and finally dissolve into the alcohol rich medium. The breakdown of chelated agglomerates is accompanied by the formation of nanosized aluminium hydroxide particles which grow with water addition into aggregated micron sized, spherical species. The chelated agglomerates evolve from a spherical geometry to a cylindrical morphology to a tapelike structure with a preferred orientation, and finally to a wavy sheet-like matrix. The nano-aluminium hydroxide particles increase in size at every water addition and grow to about 1 μm at the sonogel point.

Bath article composition

Abstract: PROBLEM TO BE SOLVED: To obtain a bath article composition having a good solubility in water for bathing, providing a refreshing feeling during or after taking a bath and causing no floating material when carbonic acid gas is generated by blending a specific component. SOLUTION: This bath article composition preferably comprises an amphoteric hydroxide such as aluminium hydroxide, an acid such as succinic acid and a carbonate such as sodium carbonate. The amount of the amphoteric hydroxide to be used in the composition is >=0.1wt.% of the total amount of the composition, further, the amounts of the acid and the carbonate are regulated so that the pH of water for bathing dissolving the bath article composition may become 5-7.

Wood imitation material and production technology thereof

Abstract: A wood-imitation material is made by using straw, seed husk as base material, and adding modified sodium silicate made from sodium silicate and sodium fluosilicate and condensed aluminium phosphate made from phosphoric acid and aluminium hydroxide through disintegrating, mixing, agitating and forming. Said invention has the advantage of no poisoness and harm, free from heating and pressurization while forming, fire-retardant, anti-pressure, water-resistant, anti-wear, anti-ageing, smooth surface and wood-feel, which is suitable for polishing, coating film etc..

High temperature resisting adhesive for steel plates, production and use thereof

Abstract: A refractory adhesive steel plates is prepared through such steps as mixing aluminium hydroxide with water, adding phosphoric acid, stirring while heating to boil, and mixing with bauxite, kaolinite and silicate sol until it becomes paste. It can be used to block leakage and repair of high-temp metal pipeline (such as the one in boiler) with high adhesion.

Value improvement of clays

Abstract: A process which allows the conversion of clay minerals of the kalonite group, to a relatively pure form of alumina and silica respectively comprising the steps of: (a) heating the kaolinite group minerals to greater than 500 °C, which causes dehydroxylation of the crystallographic lattice and formation of an intermediate meta-kaolin; (b) reacting the intermediate with only one of a selection of reagents including acids, alkalines or metalliferous compounds followed by heating of the mixture to form an aluminium salt in solution and residue of silica; (c) separation of the aluminium salt solution from the residue of silica by filtration and further treatment of the silica residue to produce a relatively pure form of fine particled silica; (d) formation of an alum by addition of ammonium sulphate in solution to the aluminium salt solution and further treatment of the alum to produce a relatively pure form of aluminium hydroxide.

Method of preparing fine crystalline corundum

Abstract: synthesis of inorganic materials, more particular manufacture of light-translucent ceramic material and leucosapphire. SUBSTANCE: thermocouple treatment of aluminium hydroxide is carried out at temperatures from 380 to 420 C and pressures from 50 to 300 atm in the presence of lower saturated alcohols methyl, ethyl, propyl or butyl in amount of 0.06-1 wt % with respect to weight of aluminium hydroxide, or with carbamide additive in amount of 0.05- 0.5 wt % with respect to weight of aluminium hydroxide. The resulting corundum samples correspond to optical class of crystals with respect to purity and are useful for facing monocrystals o leucosapphire and light-translucent ceramic material. EFFECT: pure fine crystalline corundum comprising total amount of 12 elements. 2 ex, 1 tbl

Funnel and gate subsoil contamination barrier

Abstract: The novelty is that: (b) a tenside-barrier compound uses sub-soil as a reaction face and/or water seal within the earth, or as a filter; (b) the barrier or face is creased on-site by the sequential or simultaneous action of aqueous tenside solution and iron salts and/or humins and/or aluminium salts; (c) the barrier coating is created within fluid-permeable soil or rock cavities, or on a filter or particle surface; (d) the barrier is formed by a number of layers of particles deposited by the suspended solids, which adsorb and act as catalysts, which are also biologically active and/or reactive; (e) the layers are formed by tensides and ochre, and/or humins and/or aluminium hydroxide.

Process for production of nm. alumina

Abstract: A process for preparing nm. alumina comprises impregnating kaolinite and aluminium hydroxide in circulating solution of hydrochloric acid, purification by salting out, pyrogenetic decomposition of high-purity aluminium chloride at 150-400 deg.C, activating by the addition of distilled water to obtain alumina sol, the addition of starch while heating to 80-90 deg.C to obtain alumina gel, calciningat 700-800 deg.C and phase transfer at 1100 deg.C or more.

Positive-charge charged silica-gel-granular absorption filtering material

Abstract: The silica-gel granular adsorbing-filtering material carrying positive charge is composed of aseptic granular silica-gel and aluminium hydroxide with weight ratio of 1:00023-00094 Said invented adsorbing-filtering material can adsorb virus particles in water, and its virus-adsorbing rate can be up to 986%, and its application is convenient

Bayerite: Electrochemical Synthesis and Mechanism of Formation

Abstract: A novel method of synthesis is reported for the preparation of pure and well crystallised bayerite, an aluminium hydroxide generally not obtained alone. The technique used is based on electrolysis with a cation exchange membrane between the anolyte and the catholyte. The obtained compound is then characterised using seven different techniques, namely XRD, SEM, ICP, laser diffraction, BET area, density and TGA. Our study of the kinetics of Al(OH)3 precipitation in aqueous alkali solution and theoretical calculations1 allowed us to propose a reactional mechanism for the nucleation process of crystallised Al(OH)3 and also for formation of an alumino-gel. The existence of an intermediate aluminate species in solution as a precursor of bayerite is shown in this work. Referee I: R. Kniep

Spacer for layer insulation systems of metal foils

Abstract: The spacer is formed of a pasty mass of water glass base which is applied on a foil. In an increased temperature, the pasty mass froths into a firm, foamed material. A hardener and/or thickener is added to the water glass. Aluminium hydroxide or an aluminium phosphate is used as water glass hardener, and precipitating silicic acid or pyrogenic silicic acid is used as thickener. The temperature for frothing the mass lies between 100 and 200 degrees C.

Process for producing iron-free liquid aluminium sulfate

Abstract: A process for preparing Al2(SO4)3.XH2O with 342.15 of molecular weight features the one-step reaction of aluminium hydroxide with sulfuric acid, and has the advantages of simple process flow and low cost. Obtained Al2(SO4)3.XH2O can be used as optimal sizing agent in production of high-grade white print paper.

Waterproof additive for construction material

Abstract: Waterproof additive is white powder produced with lime, stearic acid, ferrous sulfate, aluminium hydroxide, copper sulfate, alum, high-strength gypsum and animal oil and through water dissolution, heating dissolution and evaporation. With excellent waterproof and anticorrosive property, the said waterproof additive is mixed into concrete and other construction material.