Showing papers on "Aluminium hydroxide published in 1998"

Carbohydrate decomposition in beech litter as influenced by aluminium, iron and manganese oxides

Abstract: Although carbohydrates are one of the most degradable groups of soil organic matter compounds, they can accumulate in soil horizons containing strongly humified organic matter. It is therefore assumed that stabilization reactions exist, which may be related to the presence of particular mineral compounds in soils. An incubation experiment was made to investigate the influence of selected oxides (ferrihydrite, aluminium hydroxide, birnessite) on the decomposition of polysaccharides in beech litter. pH changes and the dynamics of total organic carbon, cellulosic and non-cellulosic polysaccharides, and potential cellulase activity were recorded. Carbon loss during incubation was promoted by 10% in the presence of birnessite, which acts as an oxidizing agent. Polysaccharide decomposition was hardly affected by birnessite. On the other hand, ferrihydrite and aluminium hydroxide reduced the decomposition of bulk organic matter by 12 and 65%, respectively. These mineral phases resulted in a reduction of carbohydrate decomposition by 15 and 50%, respectively. In the presence of aluminium hydroxide, there was no significant cellulose decomposition after 90 d. Nevertheless, throughout the experiment, potential cellulase activity was higher in this treatment than in the presence of birnessite. Therefore we assume that organic matter stabilization is caused by toxic effects, or by adsorption to the oxides or hydroxides, especially to aluminium hydroxide, or by both. This process tends to lower the microbial availability of organic matter and therefore to inhibit the decomposition.

Crystal Structure and Formation of the Aluminium Hydroxide Chloride [Al13(OH)24(H2O)24]Cl15 · 13 H2O

Abstract: A basic aluminium chloride with high chlorine content (basicity 1.85) has been crystallized from a concentrated aqueous solution. Its crystal structure has been determined by X-ray structure analysis. The structure contains tridecameric cations of a novel type consisting only of interconnected AlO6 octahedra. The formation of these polycations is discussed.

Effect of aluminium hydroxide and meningococcal serogroup C capsular polysaccharide on the immunogenicity and reactogenicity of a group B Neisseria meningitidis outer membrane vesicle vaccine.

Abstract: Three different formulations of an outer membrane vesicle (OMV) vaccine against group B meningococcal disease have been prepared and tested for immunogenicity and reactogenicity in adult volunteers. The vaccines were prepared with or without aluminium hydroxide and serogroup C-polysaccharide (C-ps). Doses from 12.5 to 100 micrograms protein were given twice at a six weeks' interval. All three formulations were well tolerated and highly immunogenic, inducing bactericidal and opsonizing antibodies in humans. Adsorption of OMVs to aluminium hydroxide reduced the pyrogenicity in rabbits. The differences in immunogenicity between the formulations were relatively small, but after the second dose a stronger booster response was observed when the vaccines were adsorbed. Thus, a formulation with OMVs and C-ps represents a safe and highly immunogenic vaccine, even without aluminium hydroxide.

Structure and the point of zero charge of magnesium aluminium hydroxide

Abstract: Positively charged magnesium aluminium hydroxide sol has been prepared by coprecipitation. The structure and properties were studied using X-ray diffraction (XRD), thermogravimetry (TG), differential thermal analysis (DTA), transmission election microscopy (TEM), FTIR and potentiometric titration (PT). The structure was shown to be hydrotalcite-like; the lattice constants a and c both increased with decreasing mole fraction of Al, x=[Al]/([Al]+[Mg]); the highest value of x was 0.332. Three weight loss peaks were detected by TG–DTA of the sol particles. IR spectroscopy showed that the position of the OH-stretching vibration peak shifted to high frequency and the peaks broadened with decreasing x. PT showed that the sol particles bore positive charges; the point of zero charge (pzc) and the amount of permanent positive charge both increased with increasing x.

Flameproof polymer moulding material

Abstract: The invention relates to salt mixtures of aluminium phosphinates, aluminium hydroxide and/or aluminium phosphonates and/or aluminium phosphates which are thermally stable and are suitable as flame-retardant agents for polymer moulding materials, especially for polyester and polyamides. The use of said salt mixtures is more economical and more effective than the use of aluminium phosphinates.

In situ synthesis of porous ceramics with a framework structure of aluminium borate whisker

Abstract: New porous ceramics with a framework structure of aluminium borate (9Al2O3 · 2B2O3) whiskers, in which the whiskers are distributed uniformly and randomly, can be synthesized in situ by firing of a green powder compact of a mixture of aluminium hydroxide, boric acid and an additive of nickel oxide above 1100°C. During firing, the whiskers of aluminium borate grow in situ in the compact, and are bonded together by sintering. The porous aluminium borate consists solely of whiskers, has a porosity of 85%–50%, which corresponds to a volume fraction of whiskers of 15%–50%, and a flexural strength of 2.2–56.1 MPa. Because the whiskers are strongly bonded to other whisker(s), the problem of whiskers scattering, that can be an inhalation hazard, is solved. The aluminium alloy matrix composite using this porous aluminium borate as reinforcement was fabricated by the squeeze-casting method. The tensile strength of the composite material with a whisker volume fraction of 20% can be improved by up to about 90% compared with the unreinforced matrix alloy at 350°C. © 1998 Chapman & Hall

Preparation process of alumina

Abstract: First, seed crystal aluminium hydroxide is produced through simultaneous and continuous adding of aluminium compound and acid or alkali solution, controlling pH value in certain value in the range 6-11 and producing colloid in cocurrent flow. Then, noncrystalline aluminium hydroxide and fine particle are dissolved by adding acid or alkali solution to regulate pH value to greater than 11 or lower than 4; and finally, both dissolved and newly added aluminium ions re-precipitate under the action of seed crystal by re-adding acid or alkali solution to regulate pH value to 6-11. Repeating the above said steps for 1-20 times and through ageing, washing, filtration, drying, forming and roast, alumina product is produced.

Production of aluminium hydroxide coated glass microspheres

Abstract: A process for the coating of glass microspheres with an aluminium hydroxide is described which comprises the hydrothermal treatment of a suspension of complexed Al3+-ions with glass microspheres. The aluminium hydroxide coated glass microspheres can be applied in the production of light weight glass-reinforced plastic materials e.g. for use in mass transportation.

Cryosol Synthesis of Nanocrystalline Alumina

Abstract: In the present research we employed the newly developed cryosol technique for the preparation of nanocrystalline Al(OH)3. The technique yields sols of aluminum hydroxide stable under a wide range of pH values and concentrations. Freeze-drying of the sols results in the formation of aluminum hydroxide powders with extremely low density and small particle size. Thermal behavior and phase evolution of the cryosol-derived aluminum hydroxide has been studied. According to X-ray diffraction data, annealing of cryosol-derived aluminum hydroxide results in amorphous alumina stable up to 800 °C. However DTA, electron diffraction, and 27Al NMR studies indicate that the samples amorphous to X-ray diffraction are composed of crystalline nanoparticles. The thermal stability of nanocrystals is supposed to be due to the high uniformity of the particles size distribution, the latter resulting from the synthetic method employed.

Alkyl-1-alkoxyethylphosphinous acid aluminium salts

Abstract: Alkyl-1-alkoxyethylphosphinous acid aluminium salts are produced in that alkyl-1-alkoxyethylphosphinous acids are reacted with aluminium hydroxide with a molar ratio from 3:1. The thus obtained aluminium phosphinates are used as flame-proofing agents in thermoplastic polymers, in particular polyesters.

Aluminium salts of alkylhydroxymethylphosphinic acids

Abstract: Aluminium salts of alkylhydroxymethylphosphinic acids are prepared by reacting phosphonic acids with aluminium hydroxide, paraformaldehyde, trioxane or mixtures of the same under pressure in water at 110 to 250 °C. The thus obtained aluminium phosphinates are incorporated into polymers, in particular polyesters, in which they have a fire-proofing effect.

Thermally stable aluminum hydroxide

Abstract: Printed circuit board laminates which have improved thermal stability. The improved properties are attributed to the use of a novel aluminium hydroxide which is described by the molecular representation: Al2O3·nH2O where n>2.6 and <2.9.

Process for preparing catalyst for hydrogenation of aromatic hydrocarbon

Abstract: A process for preparing hydrogenation catalyst used for hydrogenating reaction of aromatic hydrocarbon includes such steps as extruding aluminium hydroxide powder to become strips; after activating at 350-550 deg C, immersing in solution containing SiF62-; activating at 550-750 deg C to obtain carrier; and then bearing active components Ni and W to obtain catalyst Said catalyst contains NiO (10-50 wt%), WO3 (150-350 wt%), F (05-60 wt%), SiO2 (03-50 wt %) and gamma-Al2O3 (rest) features high hydrogenating activity and good hydrosaturating and hydroisomerizating performance

Catalyst and method for production of carbon and hydrogen of methane

Abstract: FIELD: production of carbon and hydrogen of hydrocarbons. SUBSTANCE: catalyst comprises, mas.%: nickel oxide, 69-74; copper oxide, 9.5-12; aluminium hydroxide, 9.5-12; iron oxide, 2-12. Catalyst is able to process methane or methane-hydrogen mixture at temperature 651-800 C, degree of utilization is 70-80 %. EFFECT: improved quality of product, improved efficiency of the method. 4 cl 1 tbla

Heat-swellable material

Abstract: A heat-swellable material, and a method for its preparation, which afford a significant increase in fire resistance temperatures are provided by phosphates of metals selected from magnesium, calcium and aluminium, in which the molar ratio of phosphorus to metal is at least 2.0:1 and the phosphate is modified by an aluminium salt or aluminium hydroxide. The proportion of water in the material is preferably in the range of 10 to 45 % by weight. The material is primarily intended for use in laminated glazing panels.

Method for production of granulated active aluminium oxide

Abstract: FIELD: production of granulated active aluminium oxide. SUBSTANCE: aluminium hydroxide is affected by mechanic activation, calcined at 280-550 C and is treated by peptizing agent. The process is followed by granulation and by drying. Polyvinyl alcohol is used as said peptizing agent. EFFECT: improved efficiency. 1 tblr

Method for production of aluminium hydroxide

Abstract: FIELD: production of catalyst carriers, catalysts and ceramics. SUBSTANCE: aluminium hydroxide is prepared by heating of metallic aluminium with aqueous solution of organic base. Ethanolamine having common formula NH n (CH 2 CH 2 OH) 3-n where n=0,1,2 is used as said organic base, molar ratio of aluminium, ethanolamine and water being 1:(0.1-10:(2-50), respectively. EFFECT: decreased cost of the process and decreased its toxicity. 3 clg

Dry barrel polishing inorganic media

Abstract: PROBLEM TO BE SOLVED: To enable even rough finish polishing by dry barrel polishing by sintering a mixed material of argillaceous particulates, abrasive particles and aluminium hydroxide particulates as a small grain shape. SOLUTION: In dry barrel polishing inorganic media by sintering a mixed material of argillaceous particulates and abrasive particles as a binding material, aluminium hydroxide is added to and mixed in the mixed material. By the aluminium hydroxide, the media can be formed not only as a cutting quality maintenance preferential type and but also can be formed as a wear-tear restraint preferential type by adjusting its adding quantity, but when 5wt.% or more is contained, a shape of the media largely collapses by sintering, and since the media having a desired shape is hardly obtained, it is desirable that 5wt.% or less be contained for a general use.

Method of preparing aluminium oxide powder to manufacture transparent ceramic products

Abstract: FIELD: building industry, more particularly preparation of aluminium oxide powder. SUBSTANCE: aluminium oxide powder is prepared by liquid phase hydrolysis carried by mixing aluminium alkoxide with aqueous solution of one or more organic polymers, at least one of which is insoluble in alcohol resulting from hydrolysis. Said aqueous solution also contains sealing additive in dissolved form. The resulting mixture is stirred. Water to aluminium alkoxide molar ratio is from 2.5 to 5.0. Total amount of said organic polymers is 3- 30 wt % of equivalent content of aluminium oxide. Alcohol and water remnants are removed from the resulting hydrolysate till hydrolysate is converted to fragile state (xerogel). When removing alcohol and water remnants from hydrolysate, hydrolysate temperature should not exceed 200 C. The resulting aluminium hydroxide xerogel is ground to particle size of not greater than 50 mcm. Ground xerogel is heat treated in the air or in other oxidative medium at 1100-1350. EFFECT: increased specific efficiency of equipment and lower power consumption. 6 cl, 1 tbla

Process for making an insulation foam and insulation foam thus produced

Abstract: In the production of an insulating foam with an ash-containing matrix, a binder and a hardener, the binder is an acid-reacting binder, especially mono-aluminium phosphate. The binder may contain an added setting accelerator, such as ammonium fluoride, magnesium oxide, aluminium hydroxide and/or talc, and the insulating foam may contain a foaming agent with added setting accelerator, selected from group VII or VIII metal compounds such as iron oxide, manganese dioxide and iron(III) sulphate. Also claimed is an insulating foam with an ash-containing matrix, a binder, a hardener and a foaming agent, the binder being an acid-reacting binder, especially mono-aluminium phosphate. Preferably, the hardener is magnesium oxide and/or fused alumina cement, optionally with monoaluminium phosphate, and the matrix contains an aluminium compound (especially the hydroxide or oxy-hydrate) and/or flyash.

Process for the preparation of aluminium hydroxychloride

Abstract: Invention belongs to aluminium oxychloride manufacturing technology that may be used for wastewater treatment. The aluminium oxychloride is being produced by mixing aluminium hydroxide with salt acid at 1/4-4.5 ratio and sulphur acid is being used as reaction initiator, amount of which is 1.5-2 per cent of the non-reacting substance total mass. Before introducing initiator into reaction it is being dissolved in salt acid and substance containing aluminium is being introduced into reactor at a solvent temperature not less than as 40 degrees by Celsius. Letting steam of 100-110 degrees by Celsius temperature through water over barboter and maintaining pressure in the reactor at 1-1.03 ata. Mixing is provided by oxygen containing gases, air, for instance. Using this production method of aluminium oxychloride does not release hydrogen and there is no blast danger.