Showing papers on "Aluminium hydroxide published in 1999"

Powder coating compositions

Abstract: A powder coating composition of the invention comprises a film-forming polymeric component having a d(v,50) in the range of from 25 to 50 microns or a d(v,70) in the range of from 25 to 70 microns, which composition incorporates by dry-blending at least one appearance-modifying additive component and a further component comprising wax-coated silica or consisting of alumina together with aluminium hydroxide. The appearance-modifying additive may be a gloss-reducing component, a texturing component, a metallic or mica component, a colouring pigment, or a further film-forming polymeric material compatible with the first film-forming polymeric material and differing in colouration therefrom, and the further additive may be alumina together with aluminium hydroxide or wax-coated silica together with alumina and/or with aluminium hydroxide or wax-coated silica. Preferably, no more than 70 % by volume of the particles in the film-forming polymeric material are less than 50 microns. A kit of the invention comprises the individual additive components prior to mixing. The kit allows for the flexibl production of a variety of finishes from a gloss powder coating composition, for example a matt or textured or metallic or sparkle finish or a matt textured finish, a matt metallic finish, an antique finish or a contrast texture or metallic sparkle finish.

Aluminium in drinking water: An overview

Abstract: Aluminium (Al) is one of the trace inorganic metals present in drinking water. In addition to the naturally occurring Al in raw waters, use of Al-based coagulants especially Al 2(SO4)3 (alum) often leads to an increase in treated water Al concentrations. A high (3.6 to 6 mg/l) concentration of Al may precipitate as aluminium hydroxide giving rise to consumer complaints. Al is also a suspected causative agent of neurological disorders such as Alzheimer’s disease and presenile dementia. During conventional water treatment processes, Al undergoes various transformations (also called ‘speciation’ of Al) which are influenced by factor s such as pH, turbidity, temperature of water source, and the organic and inorganic ligands present in water. Chemical precipitat ion, reverse osmosis, electrodialysis and cation exchange methods are efficient in Al removal from water. This paper gives an overvi ew of the presence of Al in drinking water with reference to its speciation, removal (treatment methods), water supply and health problems, and the regulation of its levels in drinking water.

Preparation and properties of some filled poly(vinyl chloride) compositions

Abstract: Different samples of filled poly(vinyl chloride) (PVC) compositions were formulated from PVC, a polar plasticizer mixture consisting of dioctylphthalate (DOP) and a chlorinated paraffin, and variable proportions of a white filler such as barite, calcium carbonate, kaoline, quartz, or talc; a conductive filler such as High Abrasion Furnace (HAF) carbon black; or a hydrated mineral filler such as aluminium hydroxide, magnesium hydroxide, or calcium hydroxide. Epoxidized soybean oil as a heat stabilizer and sandorin red (BRN) pigment were added. Electrical and mechanical studies show that the incorporation of white fillers produces a plasticized PVC of good electrical insulation character whereas the addition of HAF carbon black produces a sample with some electrical conductivity; both of them have good mechanical properties. Of the hydrated fillers studied aluminium hydroxide has been found to impart the best fire retardancy and good electrical properties for electric wires and cables. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2657–2670, 1999

The synthesis and modification of aluminium phosphonates

Abstract: Two synthetic approaches to the preparation of mixed aluminium phosphite-phosphonate solids have been made. First, the hydrothermal reaction of aluminium hydroxide (gibbsite) with mixtures of phosphorous and methylphosphonic acids under conditions that give microporous aluminium methylphosphonate-β (AlMePO-β) when methylphosphonic acid alone is used, and secondly, the reaction of AlMePO-β with increasing amounts of molten phosphorous acid. Under hydrothermal conditions there is no evidence that AlMePO-β can be prepared with phosphite groups randomly replacing methylphosphonate groups. Rather, the products are dominated over the intermediate phosphite/phosphonate compositional range by a novel phase that is thought, on the basis of 27 Al and 31 P MAS NMR and FTIR spectroscopies, to contain differing amounts of phosphite and methylphosphonate groups. Reaction of AlMePO-β with levels of molten phosphorous acid at 40% or more of the methylphosphonate content gives mixtures of AlMePO-β and a new phosphite phase, whereas reaction using lower amounts of the molten acid leaves AlMePO-β as the only X-ray visible phase. Extension of the melt method to the separate reaction of gibbsite with methylphosphonic and phosphorous acids yields, respectively, single crystals of a new aluminium methylphosphonate [Al(O 3 PCH 3 )(HO 3 PCH 3 )·H 2 O] and a known aluminium phosphite [Al 2 (O 3 PH) 3 ·4H 2 O], the structure of which had only been solved from powder diffraction data. Single crystal diffractometry improved the accuracy with which the structural parameters of the phosphite are known and enabled structure solution of the new aluminium methylphosphonate [Pnma, a=19.075(6) A, b=5.117(2) A, c=8.439(2) A], which is made up of layers that contain isolated, octahedrally coordinated aluminium linked by methylphosphonate groups.

A double-layered hydroxide, 3CaO.Al2O3.CaI2.10H2O

Abstract: The title compound, calcium oxide-dialuminium trioxide-calcium iodide hydrate (3/1/1/10), also formulated as Ca 2 Al(OH) 6 I.2H 2 O (dicalcium aluminium hydroxide iodide dihydrate), belongs to the AFm family of phases, which are hydrated products commonly encountered in cement paste. It also belongs to the more general category of compounds called lamellar double hydroxides (HDL). Its structure can be considered very close to that of the equivalent disordered sulfate compound, with the ordered I - anions replacing the disordered SO 2- 4 groups. It consists of positively charged main layers, [Ca 2 Al(OH) 6 ] + , and negatively charged interlayers, [I - ,2H 2 O], where I and O atoms occupy ordered sites. Al 3+ and Ca 2+ cations are six- and seven-coordinate, respectively, and all water molecules are bonded to Ca 2+ cations to assume the seventh coordination position. I - anions are surrounded by ten H atoms, six from hydroxyl groups and four from water molecules. These anions are therefore connected to the main layers by ten I-H hydrogen bonds, six of 3.10 (4) A and four of 2.78 (8) A, where the donors are hydroxyl groups and water molecules, respectively.

Solid-State Interaction of Aluminium Hydroxide with Lithium Salts

Abstract: The solid-state synthesis of [LiAl2(OH)6]Cl · mH2O at room and elevated temperatures from powdered solid reagents, lithium chloride and gibbsite, is described. The synthesis is performed with the help of different devices including a laboratory mixer, large-scale laboratory arm mixer, and planetary centrifugal mill. The interaction of the components depends on both the dispersity of Al(OH)3 and the nature of lithium chloride. At the initial stage, the interaction is limited by the rate of lithium chloride diffusion through the layer of the product formed. Activation energy, calculated according to the Valency–Carter equation, is 53 ± 5 kJ/mol.

Nucleation and growth of zeolite A under reagent controlled conditions. Part II

Abstract: Broad differences in the synthesis kinetics and the morphology of zeolite A from two silicate sources (soluble silicate and Ludox colloidal silica) and two different aluminium sources (aluminium isopropoxide and freshly prepared aluminium hydroxide) are reported. The differences are attributed to different rate limiting steps in the syntheses. The reactions have been followed by small angle X-ray scattering from the time of first mixing of the constituents until the final separation of zeolite A crystals. The soluble silicate and Ludox/aluminium hydroxide syntheses produce excellent cubic crystals in the 300 nm–1 µm size range. The products of the first synthesis have an interesting texture on the scale of nanometres but with aluminium isopropoxide as the aluminium source, the resulting zeolite A has a spherical morphology of size ca. 100 nm. Possible reasons for the development of these morphologies are discussed.

Process for preparing a low tfm detergent bar composition

Abstract: A low total fatty matter content detergent bar composition comprising a surfactant 25-70% total fatty matter, 9-16% by weight colloidal aluminium hydroxide and 12-52% water. The invention also comprises a process for preparing a detergent bar comprising a surfactant, 25-70% total fatty matter, 0.5-20% colloidal aluminium hydroxide and 15-52% water, comprising the steps of reacting one or more fatty acids or fats with sodium aluminate with a solid content of 20-55% wherein the Al2O3 to Na2O ratio is in the region 0.5-1.55:1 to obtain a mixture of aluminium hydroxide and soap at a temperature of between 40°C and 95°C, adding a predetermined amount of water to the mixture of aluminium hydroxide and soap, adding any further minor additives, and converting the product into bars.

Mulita a partir de hidróxido de alumínio e de sílica da casca de arroz

Abstract: Mullite was synthesised from aluminium hydroxide, Al (OH)3, previously purified from industrial rejects, and silica from acid-treated rice hulls burned at 500 oC. Although mullite synthesis started at 1300 oC, the reported experiments were performed at 1600 oC with 8.0 hours of soaking time. The apparent densities of the pure and yttria doped mullite were, respectively, 2.70 g/cm3 and 2.84 g/cm3, Yttria doped mullite microstructure shows few needle like grains as large as 30 m m. EDS analysis shows that yttria was incorporated in the mullite grains.

Method of preparing polymerization aluminium chloride

Abstract: A process for preparing polymerized aluminium chloride (PAC), especially the method for regulating its basicity features that under the pressurization aluminium hydroxide is immersed in hydrochloric acid, the extract liquid as semi-finished product is collected, and natural calcite (20-200 meshes) is used to regulate its basicity at 0-100 deg.C to obtain finished PAC liquid used to purify water. Its advantages are high purifying effect to water.

Chemical bonding of silicon carbide

Abstract: The effect of several variables such as the type of binder and additive, the temperature, time, furnace atmosphere, particle size and forming pressure, on the strength of chemically bonded SiC specimens was studied. It was shown that the highest compressive strength (43·67 MPa at 500°C) can be obtained by using optimum amounts of orthophosphoric acid and aluminium hydroxide as binder and additive respectively. Various stages in the structural development were followed by DTA, XRD and SEM/EDX analysis. It was shown that by using aluminium hydroxide and kaolin additives, phosphate bonding could be preserved at the specimen surfaces up to 1450°C. ©

Process for the manufacture of coarse aluminium hydroxide

Abstract: A process for the manufacture of coarse aluminum hydroxide via the Bayer Process The process involves the decomposition of a supersaturated alkaline aluminate liquor in a two stage precipitation process having an agglomeration stage and a growth stage The agglomeration stage takes place in agglomeration tanks, where the liquor is seeded with fine aluminum hydroxide to induce precipitation and formation of a suspension, followed by a growth stage, where the suspension is seeded with a coarse aluminium hydroxide Typically, the feed of the supersaturated alkaline aluminate liquor is split over a first agglomeration tank at a higher liquor temperature of 70° to 100° C and a second agglomeration tank or one or more of a series of second agglomeration tanks at a lower liquor temperature of 50° to 80° C

Densification study of attritor milled magnesium aluminate spinel

Abstract: Pre-synthesization of magnesium aluminate spinel was done by mixing magnesium hydroxide and aluminium hydroxide in a molar ratio of MgO: Al2O3 = 1:1 and then calcining the mixture at temperatures between 900° and 1600°C. X-ray diffraction patterns confirmed that only spinel phase was present above 1400°C. Pre-synthesized spinels were then attritor milled up to 6 h and the extent of milling was characterized by surface area measurement. Milled and unmilled materials were isostatically pressed at 175 MPa and sintered between 1550° and 1650°C for 2 h and studied for densification. A maximum of 99% densification was achieved at a sintering temperature of 1650°C.

Nuevos avances en la carbonatación del cemento aluminoso : hidrólisis alcalina

Abstract: The carbonation process of aluminous cement in presence of high alkali content is studied. In this work, the formation of a compound which formula is close to K 4 Al 6 (CO 3 ) 11-x (OH) 2x (H 2 O) y is shown for the studies samples. The aluminous cement carbonation in alkali presence take place, at least, in two stages. In a first stage the aluminium and potassium carbonate hydrate joint to CaCO 3 is formed. Later, that aluminium potassium carbonate hydrate is developed toward the aluminium hydroxide formation.

Intercalation Method for the Synthesis of Fine Aluminium Hydroxide

Abstract: A new method to synthesize fine low-alkaline aluminium hydroxide from technical-grade gibbsite has been proposed. This method is based on carrying out the cycle of intercalation–deintercalation of lithium salts within gibbsite. In order to improve the intercalation process, which requires substantial consumption of water, the electrodialysis method is proposed.

Fire-fighting high flame-proofing protective layer material

Abstract: The present invention discloses a protective layer for electric cable with high-effective fire-proof inflaming retarding function. It is mainly formed from (wt%) 68-70% of aluminium hydroxide, 22-24%of cured resin, 2.5-4.5% of epoxy resin and 2.0-3.5% of red phosphorus. The aluminium hydroxide is heated, and can be decomposed into aluminium oxide and water so as to produce the oxygen-insulating and temp.-lowering action, so that the inflamed cable can be extinguished. Said invention can provide a safety cable.

Method of producing an aggregating agent for better environment

Abstract: PURPOSE: A method of producing an aggregating agent for better environment is provided, which is characterized in the aggregating agent can make dried powder with wastewater containing heavy metals and paint and leachate by using adsorption and make biodegradable. CONSTITUTION: A method of producing an aggregating agent for better environment proceeds to the following steps: a mixing process with 0.01-20wt% of spiculisporic acid derivatives and 0.01-20wt% of absorbent polymers; and a coating process for the surface of metal-oxides or hydroxides with the mixed liquid. The metal-oxides are such as zinc oxide, aluminium oxide, potassium oxide, titanium oxide and iron oxide and the hydroxides are such as calcium hydroxide, aluminium hydroxide, zinc hydroxide and magnesium hydroxide. The absorbent polymers are a sort out of poly acrylic acid or sodium displacers, poly meta acrylic polymers and polymers of anhydrous malein acid and acrylic acid.

Method for producing the body of a catalytic converter and body of a catalytic converter

Abstract: The aim of the invention is to produce a body of a catalytic converter. To this end, an aluminium hydroxide and a metallic aluminium (4) are simultaneously and separately, thermally sprayed onto a support body (1), whereby the aluminium hydroxide is thermally converted into an aluminium oxide (3). Furthermore, an aluminium silicon composition is thermally sprayed onto the support body (1) simultaneously with and separately from the metallic aluminium (4) and a metallic active ingredient is added. A body of a catalytic converter which is produced by the thermal spraying is especially useful for decomposing harmful substances within a temperature range of more than 400° C.

Spinellisation of Magnesium and Aluminium Hydroxides with Pressure and Temperature

Abstract: An attempt has been made to study the effects of pressure and temperature on spinellisation of magnesium aluminate aggregate. The starting materials, magnesium hydroxide and aluminium hydroxide, were first characterized and then mixed for stoichiometric spinel composition. The mixed powder was then fired as loose powder and as briquettes (pressed at 1000 kg.cm−2), between 900° and 1600°C. The amount of spinellisation has been determined by X-ray diffraction method after comparing with a standard spinel sample. The results show that the briquettes have much higher spinel content and almost complete spinellisation has been obtained at 1600°C, whereas only 82.5% spinellisation was observed for the powders at the same temperature. Densification study of the briquetted samples also supports the trend of spinellisation.

Non-hygroscopic thermally stable aluminium hydroxide

Abstract: A non-hygroscopic thermally stable aluminium hydroxide is described which is particularly useful for the preparation of thermally stable and fire retardant laminates for printed circuit boards.

表面処理したスラグウールによる超微粒シリカの分離 ＊ ―界面特性を利用した超微粒子希薄懸濁液の迅速固液分離 (第 2 報) ―

Abstract: The rapid separation of fine silica particles (mean diameter of 200 nm) deposited from geothermal water were investigated by using a column bed packed with ferro-nickel slag wool. If repulsive double-layer interaction prevented particle adhesion on collector wool surface, collection efficiency greatly improved by modifying the slag wool surface with ferric hydroxide, aluminium hydroxide or aluminium silicate. In the experimental results, silica collection in 1 mM KNO3 electrolyte at pH 5 reached 17 % at dimensionless time 2 by Fe-Ni slag wool collector. On the other hand, silica recovery prominently increased up to 80 % by ferric hydroxide modification wool, 100 % by aluminum hydroxide modification wool and 85 % by aluminum silicate modification wool. These results were interpreted by the heterocoagulation theory, estimating surface interaction energy between silica particle and collector surface.

Étude de l'adsorption des hydrocarbures aromatiques polycycliques sur l'hydroxyde d'aluminium par chromatographie liquide à haute pression

Abstract: A study by high performance liquid chromatography of adsorption isotherm of HAP in toluene on Al(OH)3 heated between 25 and 700°C shows that the rate of adsorption is maximal on the Al(OH)3 heated at 300°C. The measurement of electrokinetic potential and the surface area of adsorbants approve this result. The determination of adsorption enthalpies of different HAP on the aluminium hydroxide has shown the existence of physical adsorption. The adsorbing power of Al(OH)3 heated at 300°C is compared with that of other materials known or suspected very carcinogens.Key words: adsorption isotherm of HAP, aluminium hydroxide.