Showing papers on "Aluminium hydroxide published in 1991"

Invertase β-fructosidase): Effects of montmorillonite, AL-hydroxide and AL(OH)x-montmorillonite complex on activity and kinetic properties

Abstract: The effects of a montmorillonite (M), a non-crystalline aluminium hydroxide (AL) and an Al(OH)2-montmorillonite complex (a montmorillonite partially coated with OH-Al ions; AM) on the adsorption, residual activity and kinetic properties of invertase were determined. In the range of pH 3.0–9.0 the ability of the clay minerals to adsorb protein molecules was in the order M > AM > AL and was influenced by the nature of the buffer solution. Adsorption resulted in a significant reduction of invertase activity (more than 85% at pH 4.65). the extent of which depended on clay mineral (AL > AM > M) and on pH. The free and immobilized enzyme showed maximum activity in the range of pH 4.5–5.5 and both states obeyed Michaelis-Menten kinetics. The Vmax, and Km values indicated a partial non-competitive inhibition of the clay minerals. Invertase adsorbed on AM and AL was more stable to thermal deactivation than was free enzyme, whereas invertase held on M was much less stable. In contrast, invertase adsorbed on M was more stable to the action of protease than free enzyme or that adsorbed on AM or AL.

Adsorption of heavy metals by clay - aluminum hydroxide complexes.

Abstract: In the clay fraction of soils, (hydr)oxides of Fe, Al and Mn are common. These hydroxides may differ considerably in particle size, purity, and crystallinity from the ‘model (hydr)oxides’ used frequently in laboratory studies. They may occur as discrete particles, having hardly any contact with the clay surface, and as coatings on, or as interlayers between clay mineral surfaces. Jenne (1968) suggested that the reactivity of hydroxide coatings would be considerably higher than the reactivity of free hydroxides, especially with respect to heavy metal adsorption. Since then, several authors have investigated the effect of the removal of hydroxides from soil clays on heavy metal adsorption, but their results are not unambiguous.

Influence of oral co-administered metallic drugs on ofloxacin pharmacokinetics.

Abstract: Following recent concern over probable interactions between the 4-quinolones and metal ions, the effect of co-administered drugs--sodium bicarbonate, potassium citrate, ferrous sulphate, magnesium trisilicate, calcium carbonate and aluminium hydroxide--on the saliva and urine pharmacokinetics of ofloxacin in healthy human volunteers has been investigated. The Cmax and AUC0-9 in saliva were generally in the range 1.05-1.40 mg/L and 4.89-6.16 mg.h/L, respectively, and were unaffected (P less than 0.05) by the metallic drugs, except aluminium hydroxide which lowered these values. Again, only aluminium hydroxide modified the Ka of ofloxacin, resulting in a slower absorption rate. However, none of the metallic drugs altered the T1/2 beta of the 4-quinolone in saliva. In-vitro studies using simulated gastric fluid showed that ferrous sulphate, aluminium hydroxide and calcium carbonate reduced ofloxacin availability to 67.4%, 69.3% and 73.8%, respectively. This effect was ascribed to the formation of complexes between ofloxacin and the metal ions concerned. Substantial correlation between in-vitro and in-vivo availability data was demonstrated in all cases except for ofloxacin combinations with ferrous sulphate and calcium carbonate. In general, there was also good correlation between the saliva and urine data.

Fire-proofing composition comprising metallic hydroxyde and magnesia-binders and its use

Abstract: of EP0485867The invention relates to a fire-proofing composition comprising a mixture of a water-eliminating hydroxide, especially aluminium hydroxide, with a magnesia binder, in particular a mixture of magnesium oxide and magnesium sulphate. This fire-proofing composition can be used for the manufacture of fire-proofing elements - for example as a fire-protection layer (3) in inserts (1) of fire-proof doors - and for direct fire-inhibiting filling of hollow profiles of metal, which are used, for example, as a wall part or drawer part of a fire-proof cabinet or cassette. The fire-proofing agent according to the invention especially permits easy and inexpensive manufacture of fire-proofing elements based on mineral wool.

Differential effects of sodium bicarbonate and aluminium hydroxide on the absorption and activity of glipizide.

Abstract: The effects of sodium bicarbonate and aluminium hydroxide on the absorption and activity of glipizide have been studied in healthy volunteers in two randomized cross-over trials. After an overnight fast, 5 mg glipizide was given either with 150 ml water or with water containing 3.0 g sodium bicarbonate or 1.0 g aluminium hydroxide. Sodium bicarbonate significantly increased the AUC of plasma glipizide from 0 to 0.5 h, 0 to 1 h, and from 0 to 2 h (six-, four- and twofold, respectively). The time to peak concentration (tmax) fell from 2.5 h during the control phase to 1.0 h during the sodium bicarbonate phase. The absorption half-life (t1/2a), lag time and mean residence time (MRT) were also significantly decreased. No significant change in peak plasma concentration (Cmax), total AUC or elimination half-life (t1/2) was noted. The decremental plasma glucose areas from 0 to 1 h and 0 to 2 h were significantly larger (80% and 50%, respectively) than during the control phase. The maximal decrease in glucose was 50% greater during the sodium bicarbonate phase, and the time to reach it was reduced by 35 min. Aluminium hydroxide had no significant effects on the rate or extent of absorption of glipizide, and the glucose response also remained unaffected. It is concluded that the concomitant ingestion of sodium bicarbonate and glipizide may result in accelerated absorption of glipizide and an increased effect on glucose. A common dose of aluminium hydroxide did not appear to affect the absorption of glipizide.

Effect of precipitation and aging on porous structure of aluminium hydroxide. I. Statistical treatment of experimental data

Abstract: The analysis of variance (ANOVA) was used to test the effect of changes of temperature and pH of precipitation, the time of aging and the addition of surfactants on the porous structure of dried aluminium hydroxide (containing sulphate ions). Changes in precipitation temperature effect the structure of samples, the most pronounced effect being observed in the region of large and small pores. The less distinct effect is exerted by pH of precipitation which affects especially small pores. The time of aging up to 48 h has little effect; it affects the volume of large and medium pores. The addition of surfactants during precipitation and washing leads to the increase of large and medium pores volume. Surfactants eliminate relatively efficiently the effect of aging time. Cationic and nonionic surfactants act similarly, but with different intensity, affecting the porous structure of aluminium hydroxide.

Adsorption d'acides humiques sur flocs d'hydroxydes daluminium: Influence de la taille des flocs et du sel d'aluminium

Abstract: The purpose of this study is to show that the ability of prebuilt aluminium hydroxide flocs to adsorb humic acids is function of experimental jartest conditions. The results indicate that : I/ The size of the preformed flocs is depending of the slow mixing time and of the gradient velocity mixing values. 2/ The adsorption capacity depend of the size of the floes showing that the electrostatic and ionic exchange mechanisms are mainly effective at the area of the adsorbent material. The efficiency of aluminium salts to remove humic acids are, in decrease order : WAC, aluminium sulphate, aluminium chloride, aluminium nitrate.

Calcium carbonate as a phosphate binder in dialysis patients: evaluation of an enteric-coated preparation and effect of additional aluminium hydroxide on hyperaluminaemia.

Abstract: Calcium carbonate has been successfully used as a phosphate binder in patients with chronic renal failure; however, a high frequency of hypercalcaemia has been reported. To study the effects of calcium carbonate preparations with different dissolution characteristics on the incidence of this side effect, we conducted a double-blind, crossover trial in 21 patients undergoing chronic haemodialysis. Aluminum hydroxide therapy was replaced with calcium carbonate. The subjects then randomly received either an enteric-coated or a gastric-coated preparation. Calcium carbonate (3.1-3.6 g/d) controlled serum phosphate concentrations as effectively as aluminium hydroxide (2.9 g/d). Concurrently, there was a significant rise in mean serum calcium and a fall in serum concentrations of both parathyroid hormone and osteocalcin, the latter suggesting a decrease in bone turnover. Overall, hypercalcaemic episodes developed in 9 patients (43%) and occurred at a considerable frequency (33 episodes per 100 patient-months) during treatment with the gastric-coated formulation. Following conversion to enteric-coated calcium carbonate (3.6 g/d) patients had fewer occurrences of hypercalcaemia (12 episodes per 100 patient-months, P less than 0.05) and, as compared to the gastric-coated preparation, increases in serum calcium greater than 3.00 mmol/l were not observed at all. Hyperaluminaemia was regressive during therapy with calcium carbonate, but addition of small doses of aluminium hydroxide caused a large rise in serum aluminium concentrations after infusion of desferrioxamine, indicating an enhanced rate of absorption or aberrant compartmentalization of aluminium. We conclude that calcium carbonate can control hyperphosphataemia in dialysis patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Process for the preparation of a catalyst for reforming naphtha

Abstract: Process comprising the operations consisting in acidifying aluminium hydroxide in a certain concentration between 60 and 250 DEG C in a vapour atmosphere for 2 to 15 hours and then forming and calcining the aluminium hydroxide formed between 450 and 700 DEG C to form a gamma-alumina support which is supported by Pt, Re and Ti and by halogen, the contents of the said metals and of halogen being 0.075 to 0.80 of Pt, 0.075 to 1.50 of Re, 0.00 to 0.40 of Ti, and 0.50 to 2.00 of halogen, on the basis of the % by weight of dry alumina.

Aluminiumhydroxyd for its insertion in plastic and process for its preparation

Abstract: It has not been possible to date to achieve degrees of filling of more than 160 parts of hydroxide per 100 parts of synthetic resin using milled hydroxide having an average particle size of 10-15 mu m. It is intended to develop an aluminium hydroxide for flameproofing plastics and processes for its preparation and a flameproofed plastic based on thermosetting plastics, in which the aluminium hydroxide can be incorporated with a degree of filling of more than 160 parts of aluminium hydroxide per 100 parts of synthetic resin and has an advantageous viscosity and results in a smooth surface on the finished part produced therefrom. The milled aluminium hydroxide is characterised in that the upper particle size limit of 63 mu m is limited to max. 0.5%, and that the width W of the particle size distribution, measured as W = 2ROOT d90 - 2ROOT d10, is between 4 and 5. The process for the preparation of an aluminium hydroxide is characterised in that a mill containing ceramic grinding media, such as a ball or drum mill, preferably a vibratory mill, is used. The aluminium hydroxide according to the invention is used for incorporation into plastics of the thermosetting plastic type.

Magnesium aluminate with controlled surface area

Abstract: A method of preparing magnesium aluminate having a controlled and uniform surface area comprises heating a mixture of magnesium and aluminium salts in an aqueous medium containing a nitrogen compound that decomposes slowly under the conditions of the reaction to release ammonia which reacts with said salts to form a gel comprising magnesium hydroxide and aluminium hydroxide, aging the gel, filtering and washing the aged gel, drying the filtered and washed gel, and calcining the dried gel.

Preparation of nuclei for anatase pigments

Abstract: A process for the production of a suspension of nuclei has been developed in which an aqueous mixture of titanium tetrachloride, aluminium ions and hydroxyl ions is cured at at temperature of from 50° to the boiling point. The pH of the suspension before or after curing has a value of from 6.5 to 10.5. The aqueous mixture is prepared by mixing a solution of titanium tetrachloride with a solution of a base, e.g. sodium hydroxide and aluminium hydroxide. When used to nucleate hydrolysis in the "sulphate" process a large crystal size anatase pigment is produced.

Flame-retardant filler for thermoplastic compositions

Abstract: A flame-retardant powdered filler for use in thermoplastic compositions comprises a mixture of powdered aluminium hydroxide at least the majority of which is in the alpha -trihydrate form and powdered hydrated basic magnesium/calcium carbonate. Preferably the powdered filler comprises from 25 to 80 per cent by weight of the powdered aluminium hydroxide and from 75 to 20 per cent by weight of powdered hydrated basic magnesium/calcium carbonate. The powdered filler may be incorporated in a thermoplastic polymeric base material such as ethylene vinyl acetate or ethylene co-octene to produce a flame-retardant thermoplastic composition containing about 60 per cent of the flame-retardant powdered filler.

Aluminium oxide fibres and process for producing them

Abstract: The process disclosed enables aluminium oxide fibres containing up to about 40 wt % of Sio2 to be produced by reacting aluminium hydroxide or aluminium oxide hydrate with oxalic acid in an aqueous medium, optionally in the presence of an acid such as formic acid, to give aluminium oxalate, adding silicic acid and dry-spinning the solution obtained, optionally in the presence of spinning auxiliaries, and finally heating the aluminium oxalate fibres produced.

Solid phase control of aluminium activity in an artificial plant growth medium containing hydroxy-Al-montmorillonite

Abstract: Acid deposition is an environmental concern of global importance. One of the major deleterious effects of acid deposition on the lithosphere is aluminium mobilization in the soil environment and consequent aluminium toxicity to terrestrial vegetation and aquatic biota. We applied a sulfuric acid-containing nutrient solution to an artificial plant growth medium which contained Al(OH)3 precipitated on montmorillonite (interlayer-Al(OH)3). We determined pH and total concentrations of Al, Ca, Mg, K, Na, So4, Cl, NO3 and PO4 in leachate solutions and calculated the activity of Al, K, SO4 and other ions with MINTEQA1, a computer speciation program. We found that Al activity was controlled by interlayer-Al(OH)3 when 2pH + pSO4 was less than 12.7, as long as this phase was not depleted. When 2pH + pSO4 was more than 12.7, the Al activity followed a line parallel to crystalline alunite, implying an unknown Al-controlling phase of the same Al/S/K/OH ratio, but more soluble than the crystalline alunite. We propose that this unknown phase is amorphous alunite. The re-examination of several sets of published data for naturally-acidic surface and ground waters, mine waste drainage water, and solutions from acidic soils and sediments revealed that the Al activity in those solutions fell between what would be expected for equilibrium with the proposed amorphous alunite (upper limit) and the crystalline alunite (lower limit). This implies that an alunite-like aluminium sulfate may have controlled Al activity in natural environments that were influenced by sulfate and proton input from either natural or manmade causes.

Process for preparing nickel sulfate

Abstract: This invention relates to a process for preparing nickel sulfate with metal nickel extracted from the catalyst whose activity has lost. It features as follows: Any waste Ni, Al catalysis containing Ni reacts with HsSO4 until pH value is equal to 4-5; The reaction liquor is taken out and reacts with calcium carbonate in an Al removing tank; When pH value is equal to 5.5-6, all of Al and Ca become aluminium hydroxide and calcium sulfate which are educed from solution by deposition. Other steps include removing Fe and Zn, filter, evaporation, crystallization, drying by revolution, chemical examination and package. Its advantages include thorough recovery of nickel (up to 99%), short technological route, simple equipment and operation, and less investment. Its quality meets class 1 national standard.

Mechanism of electrolytic coloring of anodized aluminum

Abstract: La formation d'un gel dans les pores de l'aluminium anodise joue un role important dans le mecanisme de coloration electrolytique.

The Effect of Aluminium Loading on Bones of Mice

Abstract: A number of studies have been carried out on the toxic effect of aluminium on bone mineralization and its relation to calcium and parathroid-hormone metabolism. Exposure to aluminium by the means of either diasylate or ingestion of aluminium hydroxide or both leads to its deposition in tissues, particularly in bone. This deposition blocks incorporation of calcium into osteoids, leading to the osteomalacia characteristic of aluminium-induced bone disease (Drucke 1980; Alfrey 1980; Cournot-Witmer et al 1981; Walker et al 1982; Mayor et al 1980; Cann et al 1979; Cannata et al 1983; Boyce et al 1982). Therefore, the effects of aluminium hydroxide loading on bone of mice were examined. Besides aluminium, the calcium level of the same bone samples were determined and aluminium/calcium ratios were evaluated in this study. The aluminium and calcium measurements have been performed by graphite furnace and flame atomic absorption spectrometry respectively.

Process for production of nuclei for use in titanium dioxide manufacture

Abstract: A process for the production of a suspension of nuclei has been developed in which an aqueous mixture of titanium tetrachloride, aluminium ions and hydroxyl ions is cured at at temperature of from 50° to the boiling point. The pH of the suspension before or after curing has a value of from 6.5 to 10.5. The aqueous mixture is prepared by mixing a solution of titanium tetrachloride with a solution of a base, e.g. sodium hydroxide and aluminium hydroxide. When used to nucleate hydrolysis in the "sulphate" process a large crystal size anatase pigment is produced.

Advantage of Early Initiation of Aluminium Hydroxide Administration for the Prevention of Experimental Progressive Renal Disease

Abstract: Aluminium hydroxide, a phosphate binder, is regarded as a strong candidate to halt the progression of chronic renal disease. In order to determine the most effective time to start treatment, aluminium hydroxide was administered either immediately (ADR-0w), or at 8 weeks (ADR-8w) or 16 weeks (ADR-16w) after repeated injection of Adriamycin (ADR) inducing glomerular sclerosis. In the aluminium hydroxide-untreated group the survival rate at the end of the experiment was 50%, while the early initiation of aluminium hydroxide (ADR-0w) resulted in a greater survival rate of 90%. Serum phosphate concentration and serum calcium-phosphate product were significantly less in the aluminium hydroxide groups (ADR-0w, 8w, 16w) than in the untreated group after week 20. Urinary protein excretion was significantly less in the ADR-0w and ADR-8w groups at week 12 or 16 compared to the aluminium hydroxide-untreated group. Blood urea nitrogen in the aluminium hydroxide groups was significantly less than that in the untreated group at week 34. Histological examination revealed that glomerular sclerosis was less severe in the ADR-0w and ADR-8w groups than in the aluminium hydroxide-untreated group, and glomerular hypertrophy was significantly decreased in the ADR-0w group. We conclude that early treatment with aluminium hydroxide was effective in preventing renal deterioration in focal glomerular sclerosis induced by Adriamycin.

Production of readily grindable alumina

Abstract: PURPOSE:To obtain easily grindable alumina by pyrolyzing Bayer's method aluminium hydroxide at a specific temperature-raising rate, calcining the product and further calcining the prepared intermediate calcination alumina containing alpha-alumina as a main component in the presence of a mineralizing agent. CONSTITUTION:Aluminum hydroxide prepared by Bayer's method is pyrolyzed at a temperature-raising rate of <=20 deg.C/min to produce gamma-alumina free from water of crystallization. The gamma-alumina is subjected to an intermediate calcination treatment to prepare intermediately calcined alumina, which is further calcined in the presence of a mineralizer (e.g. aluminum fluoride) preferably at a temperature of 600-1500 deg.C to provide the objective alumina. The grinding of the prepared alumina for a short time permits to provide spherical alumina powder having a narrow fine particle diameter distribution of approximately 1-3mum and suitable as a raw material for ceramics.

Bauxite digestion in ball mill - for simultaneous fine grinding, leaching and silica removal

Abstract: In bauxite digestion by simultaneously leaching and grinding bauxite with caustic soda in a ball mill, the novelty is that (i) the mill is a stirred ball mill; (ii) the charge also contains lime in an amt. corresp. to the stoichiometric amt. of 1-3 (1.8-2.2) mol. CaO per mol. SiO2 which otherwise goes into soln.; and (iii) the mill (or its contents) is heated to 80-98 (88-92) deg.C. ADVANTAGE - Process effects simultaneous fine grinding, leaching and silica removal, without Al2O3 and Na2O losses during silica removal and without red mud formation. After cooling obtd. aluminate liquor, aluminium hydroxide pptn. is induced by stirring so pptn. duration is shortened and hydrated alumina yields are increased.

Process for sizing papers containing calcium carbonate with resinous dispersions.

Abstract: In the sizing of papers containing calcium carbonate with resin size dispersions, the procedure for avoiding decomposition of the calcium carbonate by the solutions, used for the precipitation and fixing of the resin size, of aluminium salts having an acidic reaction, is as follows: An aqueous colloidal solution of homogeneous aluminium hydroxide is prepared, which contains 0.1 to 50 g/litre of aluminium hydroxide and has a pH of 6 to 8. During or immediately after its formation, this colloidal solution is mixed under turbulent flow conditions with the paper pulp or the resin size dispersion. To prepare the colloidal solution, an aqueous solution containing 1 to 40 g/litre of an aluminium salt having an acidic reaction can either be mixed under turbulent flow conditions in the stoichiometric ratio with an aqueous solution which contains 1 to 50 g/litre of at least one substance having an alkaline reaction, or it can be passed over an anion exchanger in the OH form.

Preparation of aluminum hydroxide of short prism type

Abstract: A process for preparing a short-prismatic aluminium hydroxide by decomposing a supersaturated sodium aluminate hydroxide and the use of the product as pigment and filler in the paper industry, as a flame-retardant filler in plastics and as a white pigment in colours and paints.

Process for producing ceramic aluminium oxide articles

Abstract: According to the process of the present invention, an aluminium compound, preferably aluminium hydroxide, boehmite, gamma-aluminium oxide or alpha-aluminium oxide or a mixture thereof is activated by means of additives and sintered in order to obtain shaped, ceramic articles. The process of the present invention comprises adding in each case either yttrium oxide or lanthanum oxide or neodymium oxide or an equivalent amount of a salt thereof which can be converted into the corresponding oxide by heating to separate batches of aluminium compound or aluminium compounds in an amount of at least 0.05% by weight, based on the aluminium oxide content; separately homogenizing the separately obtained mixtures by milling and subjecting them to a thermal treatment at a temperature of at least 1450 degree C so that at least 80% by weight of the additives react with aluminium oxide; subsequently mixing two or three of the activated aluminium oxides obtained in this way, milling the resulting mixture which has a total additive content of from 0.01 to 1.0% by weight in the form of the pure oxides, and subsequently converting the resulting ceramic raw materials into shaped articles by known methods and finally sintering them at a temperature above 1450 degree C.