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Showing papers on "Aluminium hydroxide published in 1994"


Journal ArticleDOI
TL;DR: In this paper, the effect of different exposures to soluble phosphate was investigated using 27Al and 71P solid-state magic-angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy.
Abstract: Summary The sorption of phosphate on amorphous aluminium hydroxides was investigated using 27Al and 71P solid-state magic-angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy, following the effect of different exposures to soluble phosphate. The spectra obtained were compared with the spectrum of amorphous aluminium phosphate. Aluminium in the unreacted hydroxide had a 100% octahedral co-ordination. When dried at 200°C and exposed to soluble phosphate, very little (maximum 0.1%) amorphous aluminium hydroxide transformed to a tetrahedral co-ordination (A1 bound by oxygen bridges to four P atoms), even after 120d. The tetrahedral co-ordination exists in aluminium phosphate gel, although most of its A1 atoms exhibit an octahedral co-ordination. For the aluminium hydroxide dried at 200°C, no formation of aluminium phosphate in which aluminium is in octahedral co-ordination could be detected, not even when the aluminium hydroxide was exposed to a phosphate solution for 120 d. We concluded that the formation of aluminium phosphate is restricted to the surface of the hydroxide. Most of the phosphate which is bound to the aluminium oxide however may not have formed a ‘bulk solid’ aluminium phosphate, but is adsorbed on the internal and external surface of the oxide. The same amorphous aluminium hydroxide, dried at 70°C instead of 200°C, is converted much more rapidly to aluminium phosphate when exposed to soluble phosphate. We propose a P-induced weathering mechanism to describe P sorption on amorphous aluminium hydroxides at high P concentrations. In addition to NMR, phosphate adsorption experiments conducted on aluminium hydroxides dried at different temperatures produced evidence that the porosity of the aluminium hydroxide aggregated particles can also be a factor controlling the rate of phosphate uptake from solution, if the aggregate is stable (is not resuspended) in solution.

67 citations


Journal ArticleDOI
01 Jan 1994-Vaccine
TL;DR: The physicochemical properties of the antigen-adjuvant complex and not the adjuvant alone should be considered during vaccine preparation.

66 citations


Journal ArticleDOI
TL;DR: The clinical significance of increased drug absorption is not clear, however, accelerated and enhanced absorption of analgesic drugs may be beneficial when rapid pain relief is desired and an unexpectedly increased hypoglycaemic or anticoagulant effect may be potentially dangerous.
Abstract: Antacids are widely used for many disorders. The potential of antacids to interact with other concomitantly ingested drugs is well recognised. These interactions usually result in reduced or delayed absorption of the affected drug. However, this is not always the case. In contrast to aluminium hydroxide, magnesium hydroxide and sodium bicarbonate can enhance the absorption of some drugs. For example, magnesium hydroxide can increase the rate and sometimes even the extent of absorption of certain nonsteroidal anti-inflammatory drugs (e.g. tolfenamic acid, mefenamic acid and ibuprofen), sulphonylurea antidiabetic agents [e.g. glipizide, glibenclamide (glyburide) and tolbutamide] and the oral anticoagulant dicoumarol (bishydroxycoumarin). These weakly acidic drugs are nonionised at gastric pH, but are sparingly water soluble. Elevation of the gastric pH by administration of magnesium hydroxide or sodium bicarbonate increases the solubility and absorption of such sparingly water soluble agents. Chelate formation may be involved in the increased absorption of dicoumarol by magnesium hydroxide. In combination antacids containing both aluminium hydroxide and magnesium hydroxide, the absorption enhancing effect of magnesium hydroxide seems to be counterbalanced by the opposing effects of aluminium hydroxide. The clinical significance of increased drug absorption is not clear. However, accelerated and enhanced absorption of analgesic drugs may be beneficial when rapid pain relief is desired. In contrast, an unexpectedly increased hypoglycaemic or anticoagulant effect may be potentially dangerous. Therefore, a knowledge of the potential effect of antacids on the absorption of other drugs is clinically important.

50 citations



Journal ArticleDOI
TL;DR: In this paper, an electrolytic method for the synthesis of an alumina barrier on stainless steel with strong interfacial bonding is described for a Fe-17%Cr alloy, which was laid down electrochemically after a specific conversion treatment by chemical oxidation of the substrate in acid solution.
Abstract: An electrolytic method for the synthesis of an alumina barrier on stainless steel with strong interfacial bonding is described for a Fe-17%Cr alloy. The deposit was laid down electrochemically after a specific conversion treatment by chemical oxidation of the substrate in acid solution. The conversion coating was very porous and had excellent adhesion at the substrate interface. Alumina was obtained by thermal dehydration of aluminium hydroxide deposited from an aqueous solution of an aluminium salt, according to a two-step mechanism: generation of hydroxyl ions at the cathodic substrate by reduction of H2O or dissolved oxygen and a precipitation reaction forming aluminium hydroxide. Thermal treatment induced interfacial reactions between aluminium oxide and conversion coating compounds which led to spinel formation beneath the superficial alumina layer. The coating presented chemical composition gradients suitable for strong adhesion. Thermal oxidation resistance was studied in air at 1000° C.

44 citations


Journal ArticleDOI
TL;DR: Although in this study aluminium hydroxide was given at doses higher than those usually consumed by pregnant women, no signs of maternal or developmental toxicity were observed when the compound was given alone or concurrently with high doses of ascorbic acid.
Abstract: The present study was conducted to assess if the concurrent ingestion of high doses of aluminium hydroxide and ascorbic acid might result in maternal and developmental toxicity in mice. Three groups of pregnant Swiss mice were given by gavage daily doses of aluminium hydroxide (300 mg/kg), ascorbic acid (85 mg/kg), or aluminium hydroxide (300 mg/kg) concurrent with ascorbic acid 85 (mg/kg) on gestational days 6-15. A fourth group of animals received distilled water and served as control group. Dams were killed on gestation day 18 and foetuses were examined for external, internal, and skeletal abnormalities. The reproductive data did not show embryotoxic or foetotoxic effects in any group. No gross, internal, or skeletal malformations or variations related to the different treatments were found. There were no significant differences between control and treated groups on the aluminium levels in maternal liver and bone as well as in whole body foetuses, whereas aluminium concentrations were significantly higher in placenta and kidney of dams receiving aluminium hydroxide and aluminium hydroxide plus ascorbic acid than in those from the control group. Although in this study aluminium hydroxide was given at doses higher than those usually consumed by pregnant women, no signs of maternal or developmental toxicity were observed when the compound was given alone or concurrently with high doses of ascorbic acid.

31 citations


Journal ArticleDOI
01 Aug 1994-Gut
TL;DR: The fresh perfusate was shown by ultrafiltration to contain largely particulate/colloidal aluminium-hydroxide, and this probably adhered to intestinal mucus which may be an important barrier to the gastrointestinal absorption of aluminium.
Abstract: An aluminium (93 microM) sulphate solution freshly adjusted to pH 7.0 was perfused through the rat small bowel to mimic the reported physiological conditions that follow dietary aluminium ingestion. One third of this aluminium was taken up from the perfusate, but > 90% of this was then recovered from the intestinal mucus/mucosa and most (> 70%) from the distal third of the small bowel. The fresh perfusate was shown by ultrafiltration to contain largely particulate/colloidal aluminium-hydroxide, and this probably adhered to intestinal mucus which may be an important barrier to the gastrointestinal absorption of aluminium.

24 citations


Journal ArticleDOI
TL;DR: In this article, an improved method for removal of fluorine from ground water and chromium simultaneously from industrial waste waters is presented, which consists of two stages, first iron(II) and calcium hydroxide solutions are added and the sediment is separated.

24 citations


Journal ArticleDOI
01 Jan 1994-Vaccine
TL;DR: Studies of protein adsorption using bovine serum albumin as a model protein revealed a direct relationship between the albumin adsorptive capacity and the width at half height (WHH) of the (020) reflection in the X-ray diffraction pattern.

16 citations


Journal ArticleDOI
TL;DR: In this article, small-angle X-ray scattering (SAXS) measurements made at various stages of the aging process showed that, in addition to fractal aggregation, there is a second process active in the solutions that leads to the break up of the fractal structure and formation of nonfractal particles, which are probably Al13 ions, [AlO4Al12Al12(OH)24(OH2)12]7+.
Abstract: Aluminium hydroxide particles, created by hydrolysis of aluminium nitrate solutions with sodium carbonate, aggregate rapidly to form mass fractal structures for which the fractal dimension varies from 1.7 to 2.1 depending on the OH/Al-ion ratio of the solution. This system has been studied by small-angle X-ray scattering (SAXS). The OH/Al ratios for the solutions were 1.5, 2.0 and 2.15. The maximum radius of gyration of the aggregates of about 50 A is found in the solutions having the highest OH/Al ratio. SAXS measurements made at various stages of the aging process show that, in addition to fractal aggregation, there is a second process active in the solutions that leads to the break up of the fractal structure and formation of nonfractal particles, which are probably Al13 ions, [AlO4Al12(OH)24(OH2)12]7+. This process, which is strongly temperature dependent, is governed by an activation energy of approximately 162 kJ mol−1.

10 citations


Patent
17 Mar 1994
TL;DR: In this paper, the composite panels with high fire-proofing capacity have two outer layers and a core that features a core mixture containing aluminium hydroxide in compacted form.
Abstract: Composite panels with high fire-proofing capacity have two outer layers and a core that features a core mixture containing aluminium hydroxide in compacted form, lightweight fillers, in some cases fine grained or splintery aluminium hydroxide, as desired magnesium hydroxide and polymer-based binding agents. The composite panels are suitable e.g. as facade panels for building constructions.

Journal ArticleDOI
TL;DR: In this paper, the processing of alumina ceramics using the sol-gel technique was investigated, and the progress of the reactions occurring at various stages of the process was studied using pycnometry, TG-DSC, XRD, SEM, MIP and TEM techniques.
Abstract: The processing of alumina ceramics using the sol-gel technique was investigated. Alumina sols were prepared by precipitation-peptization of aluminium hydroxide obtained from aluminium nitrate and aluminium oxyhydroxide obtained from aluminium isopropoxide. Sols cast on Teflon substrate were gelled by controlled dehydration at near-ambient temperature. Gels were converted to ceramics through processes of drying, calcination and sintering in the temperature range 773–1473 K. Ceramics derived from both the sols retained a porosity of 35–45% even after sintering at 1273 K. However, at 1473 K densification was drastically enhanced and bodies could be sintered to about 90–93% of theoretical density (TD) and was accompanied by theϑ-to-α transformation. The progress of the reactions occurring at various stages of the process was studied using pycnometry, TG-DSC, XRD, SEM, MIP and TEM techniques.

Journal ArticleDOI
TL;DR: In this paper, the influence of the addition of boron, calcium, magnesium, zirconium and zinc compounds on the physicochemical properties of alumina supports has been studied.
Abstract: The influence of the addition of boron, calcium, magnesium, zirconium and zinc compounds on the physicochemical properties of alumina supports has been studied. Dopants were introduced during aluminium hydroxide precipitation. It was concluded that the effect of dopant incorporation depends on the type of additive and its concentration in the precipitated slurry. Aluminas doped with boron and magnesium showed the best physicochemical properties as hydrorefining catalyst supports. The obtained results are discussed on the basis of the open literature results.

Patent
16 Dec 1994
TL;DR: In this paper, a process for the production of plastic sanitary articles based on polymethyl methacrylate having improved thermal properties by the casting resin process is described, in which a suspension of the liquid, polymerisable, organic precursor is transferred into a shaping mold and cured in a manner known per se and subsequently demoulded, characterised in that the particulate filler FS is selected from the group consisting of aluminium oxide, aluminium hydroxide, aluminium oxide hydrate, aluminium dioxide hydrate and silicon dioxide, with the proviso that the average particle size of the
Abstract: The invention relates to a process for the production of plastic sanitary articles based on polymethyl methacrylate having improved thermal properties by the casting resin process, in which a suspension of the liquid, polymerisable, organic precursor is transferred into a shaping mould and cured in a manner known per se and subsequently demoulded, characterised in that the particulate filler FS is selected from the group consisting of aluminium oxide, aluminium hydroxide, aluminium oxide hydrate, magnesium hydroxide and silicon dioxide, with the proviso that the average particle size of the filler particles FS is in the range from 20 to 60 mu m, and that the particles have been silanised by means of a non-ethylenically unsaturated silanising reagent.

Patent
13 May 1994
TL;DR: Barium-stabilised alumina has a specific surface of greater than 40 (pref. greater than 45) sq.m/g, after calcination at 1200 deg.C for 4 hours.
Abstract: Novel barium-stabilised alumina has a specific surface of greater than 40 (pref. greater than 45, esp. greater than 50) sq.m./g, after calcination at 1200 deg.C for 4 hrs.. Prepn. of the above stabilised alumina, from an alumina powder produced by rapid dehydration of an aluminium hydroxide or oxyhydroxide, involves subjecting the powder to maturation and then heat treatment, the novelty being that maturation is carried out in the presence of one or more barium cpds. as stabilising agents. USE/ADVANTAGE - Claimed uses of the stabilised alumina are as (i) a catalyst support, esp. in treatment of i.c. engine exhaust gases; and (ii) a catalyst, esp. in fluid catalytic cracking. The stabilised alumina has good thermal stability, maintains a high specific surface at high temp. and contains uniformly distributed barium.

Journal ArticleDOI
TL;DR: In this article, aluminium hydroxide was prepared from aluminium sulfate solutions of varying concentration in order to check the possibility of higher yield and the Sintering behaviour of this alumina powder has been studied and 99% theoretical density was achieved in 3 h at 1600°C without MgO or grain growth inhibitor.

Patent
30 Nov 1994
TL;DR: In this paper, the dearsenicating agent for hydrocarbons is prepared by mixing aluminium hydroxide whose monohydrated alundum content is greater than 65% with the one whose apeture was greater than 1000A, shaping, calcining to obtain gamma-Al2O3 carrier, immersing the carrier in dipping solution prepared from Ni salt and ammonia water, drying and calcining.
Abstract: The dearsenicating agent for hydrocarbons is prepared by mixing aluminium hydroxide whose monohydrated alundum content is greater than 65% with the one whose apeture is greater than 1000A, shaping, calcining to obtain gamma-Al2O3 carrier, immersing the carrier in dipping solution prepared from Ni salt and ammonia water, drying and calcining. Its Ni content is 12-40 wt.%. The carrier has high strength and higher arsnic-carrying capacity to gasoline, naphtha, or raw gas.

Journal ArticleDOI
TL;DR: A rapid and sensitive spectrophotometric method has been developed based on the extraction of the ionassociation complex formed between ICl2− and Rhodamine 6G+ into benzene as discussed by the authors, which is formed through iodine which is liberated during the oxidation of iodide by the selenium(IV) present in sulfuric acid medium.
Abstract: A rapid and sensitive spectrophotometric method has been developed based on the extraction of the ion-association complex formed between ICl2− and Rhodamine 6G+ into benzene The ICI2− is formed through iodine which is liberated during the oxidation of iodide by the selenium(IV) present in sulfuric acid medium The method is sensitive and down to 01 μg selenium could be determined in an aqueous phase volume of 10 ml The extracted Rhodamine 6G+–ICl2− complex has a molar absorptivity of 48 × 105 dm3 mol−1 cm−1 at 535 nm Beer’s law is obeyed over the range 01 to 09 μg of selenium The relative standard deviation is 24% The method is made more sensitive and selective by adopting the aluminium hydroxide collection procedure The interference of few ions such as Fe3+, VO3−, TeO32− and Sb5+ which were collected along with selenium on aluminium hydroxide, were overcome by adding proper masking agents The method was applied to the determination of selenium in environmental ash sample, copper ore, bark sam

Patent
04 Mar 1994
TL;DR: In this paper, the authors proposed composite panels having high fire protection performance and comprising two outer layers and a core, with the core containing a core mixture and the core mixture containing aluminium hydroxide in compacted form.
Abstract: Composite panels having high fire protection performance and comprising two outer layers and a core, with the core containing a core mixture and the core mixture containing aluminium hydroxide in compacted form, light fillers, if appropriate finely divided or splintery aluminium hydroxide, if desired magnesium hydroxide and binder based on polymers. The composite panels are suitable, for example, as facing panels for above-ground buildings.

Patent
Legat Werner1
22 Sep 1994
TL;DR: In this article, a process for separating off CO2 from exhaust gases is described, in which the absorption proceeds in the presence of basic substances such as NaCl, KCl, FeCL3, AlCl3, and AlCl 3.
Abstract: A process is described for separating off CO2 from exhaust gases. The absorption proceeds in the presence of basic substances sodium hydroxide solution, potassium hydroxide solution, iron hydroxide or aluminium hydroxide by means by CaCl2 from the Solvay soda process. The CaCO3 formed as well as the reaction products formed from the basic substances, e.g. NaCl, KCl, FeCL3, AlCl3, are reusable raw materials.

Patent
09 Mar 1994
TL;DR: In this article, a preparation method of catalyst-cracking-catalyst using aluminium collosol as the adhesive, kaolin as filling agent, and ZSM-5 molecular sieve as active ingredient was described.
Abstract: The present invention relates to a preparation method of catalyst-cracking-catalyst. It uses aluminium collosol as the adhesive, kaolin as filling agent, Y-type molecular sieve or ZSM-5 molecular sieve as active ingredient. It is characterized by that the described aluminium collosol adhesive is a basic aluminium chloride prepared by using clay mineral, bauxite, coal gangue, crystalized aluminium hydroxide or aluminium dust as raw materials.

Journal ArticleDOI
TL;DR: In this article, the effect of the medium of aluminium hydroxide precipitation composition on the thermal behavior of the respective alumina has been invesitgated and the effects of ion present in the medium have been investigated.
Abstract: Effect of the medium of aluminium hydroxide precipitation composition on the thermal behavior of the respective alumina has been invesitgated. Ions present in the medium of precipitation of aluminium hydroxide affect the recrytallization and thermal stability of surface area and the pore structure of the resulting alumina.


Journal Article
TL;DR: In this article, the dynamics of some components of the liquid phase during consecutive acidic extractions from organogenic and podzolic horizons of Podzolic soils were investigated to revel the basic mechanisms of the interaction groups of organic acids.
Abstract: The dynamics of some components of the liquid phase during consecutive acidic extractions from organogenic and podzolic (eluvial) horizons of Podzolic soils were investigated to revel the basic mechanisms of the interaction groups of organic acids was found to be the most significant reaction between acid and acid organogenic horizons of Podzolic soils. The activity of Al 3+ in the liquid phase can be adequately calculated from the precipitation-dissolution reaction of aluminium hydroxide with correction for hydrolysis with the formation of monomeric and polymeric compounds

Journal ArticleDOI
TL;DR: In this article, it was shown that the added fluoride influences the process of polymorphous transformation of the formation of α-Al2O3 from Al(OH)3, in the range of 0. 1 to 10 percent.
Abstract: The aim of this work was to check the possibility that by use of infrared spectroscopy the influence of fluorides on the calcinations process of aluminum hydroxide can be followed. The DTA method shows it clearly. It was, namely, found that the added fluoride influences the process of polymorphous transformation of the formation of α-Al2O3 from Al(OH)3. According to DTA, IR, and X-ray analyses, it was found that the added fluoride lowers the temperature of the mentioned transformation for some 300 degrees. For this purpose recorded were IR spectra and X-ray difractograms of pure AI(OH)3 as well as of such samples with added fluoride, in this case of AlF3, in the range of 0. 1 to 10 per cent. The samples were examined in the temperature range of 298 to 1673 K in different time intervals.

Patent
19 Apr 1994
TL;DR: In this article, caesium aluminium alum is reacted with an amount of calcium hydroxide which is equimolar with the aluminium and with a calcium salt readily soluble in water.
Abstract: In the method proposed, caesium aluminium alum is reacted with an amount of calcium hydroxide which is equimolar with the aluminium and with an amount of a calcium salt readily soluble in water which is equimolar with the caesium in a single flask in the presence of water and the aluminium hydroxide and calcium sulphate which precipitate out are separated off by filtration or centrifugation.

Patent
15 Mar 1994
TL;DR: In this paper, a new crystalline aluminium hydroxide is described, which is especially well suited for flarne-proofing of thermosetting plastics dlat are used in electrical applications.
Abstract: Described is a new crystalline aluminium hydroxide which, because of its high-level purity and its outstanding electrical properties along with good viscosity characteristics, is especially well-suited for flarne-proofing of thermosetting plastics dlat are used in electrical applications.