Showing papers on "Aluminium hydroxide published in 1982"

Chemical and colloidal stability of sols in the Al2O3-Fe2O3-SiO2-H2O system: their role in podzolization

Abstract: Summary Concentrations of dialysable silica in equilibrium with Al2O3-SiO2-H2O sols at pH 4.5–5.0 confirm the formation of a poorly ordered non-dialysable proto-imogolite species with an Al : Si ratio near 2, close to that of imogolite. Sols with Al : Si>2 give nearly constant levels of free silica in solution in the range 2–6 μg/cm3, indicating equilibrium between proto-imogolite and aluminium hydroxide species. These findings indicate that imogolite-like precipitates in acid soils will buffer silica in solution to within this range during leaching episodes. Imogolite is more stable than a previous estimate suggested, and a revised value for its free energy of formation is proposed: ΔG0f(298.15) = -2929.7 kJ/mol. In Fe2O3-SiO2-H2O sols, the Fe : Si ratio of the non-dialysable species varies smoothly from 11 to 3 as free silica in solution ranges from 4 to 35 μg/cm3. Such sols are much less colloidally stable than hydroxyaluminium silicate sols, but mixed Al2O3—Fe2O3—SiO2—H2O sols are almost as stable as iron-free sols up to a Fe : Al ratio of 1.5. Thus migration of Al and Fe as mixed hydroxide sols can account for the almost constant ratio of Al to Fe with depth in oxalate extracts from Bs horizons of podzols.

Aluminium hydroxide granulomas: light and electron microscopic studies and X-ray microanalysis.

Abstract: SUMMARY Three children are described in whom painful subcutaneous nodules developed 1–2 years after the injection of adsorbed diphtheria, tetanus and pertussis vaccine. The diagnosis of aluminium hydroxide granuloma was established by ultrastructural examination with X-ray microanalysis.

The effect of oral aluminium therapy on plasma aluminium levels in patients with chronic renal failure in an area with low water aluminium.

Abstract: In a low water aluminium area ( less than or equal to 04 micromoles/1) plasma aluminium levels were normal in 31 non-dialyzed and 7 peritoneally-dialyzed patients unless oral aluminium hydroxide was prescribed Plasma aluminium levels were above normal in 26 patients on maintenance hemodialysis, but when aluminium hydroxide intake stopped there was a decrease in pre-dialysis plasma aluminium Poor compliers (indicated by plasma phosphate levels) showed no change Oral aluminium hydroxide can make a major contribution to plasma aluminium levels in patients with renal failure and should be treated with the same caution as high dialyzate aluminium Post-dialysis plasma aluminium levels were always higher than pre-dialysis levels both on and off aluminium therapy despite the low dialyzate aluminium concentration This rise may be due to tissue redistribution

Effect of aluminium hydroxide on serum ionised calcium, immunoreactive parathyroid hormone, and aluminium in chronic renal failure.

Abstract: According to the Bricker-Slatopolsky theory, secretion of parathyroid hormone (PTH) is switched on in chronic renal failure by hypocalcaemia due to phosphate retention. In an attempt to reverse this process 20 patients in preterminal renal failure (plasma creatinine 569 +/- 195 mumol/l) were given aluminium hydroxide, 3.8 g daily. They were studied for four weeks and all measurements were made at the start and weekly, except measurements of serum aluminium concentration, which were made at the start and at the end of the fourth week. Mean serum phosphate fell from 1.89 to 1.47 mmol/l (5.9 to 4.6 mg/100), mean serum calcium rose from 2.07 to 2.24 mmol/l (8.3 to 9.0 mg/100 ml), and serum ionised calcium rose from 1.07 to 1.20 mmol/l (4.3 to 4.8 mg/100 ml), but serum immunoreactive PTH did not fall. Thirteen patients had initial serum immunoreactive PTH concentrations at or near to normal and 11 were taking beta-blockers but even in those with neither explanation, PTH concentrations did not fall. Serum aluminium concentrations rose from 0.4 to 1.02 mumol/l (10.9 to 27.4 microgram/l). Aluminium hydroxide corrects serum phosphate, total calcium, and ionised calcium at the price of a rise in serum aluminium concentration; in this study it did not affect serum immunoreactive PTH. The Bricker-Slatopolsky theory still needs verification in studies of patients with chronic renal failure.

Polymerization of Silicic Acid Adsorbed on Aluminium Hydroxide

Abstract: Factors controlling the absorption of silicic acid on aluminium hydroxide from aqueous solution and the polymerization of adsorbed silicic acid were studied. Measurements included the amount of silicic acid adsorbed on aluminium hydroxide, the amount and size distribution of the polysilicic acid formed, and the differential thermal analysis curve of aluminium hydroxide which had adsorbed silicic acid. The adsorption and the polymerization of silicic acid are affected by pH, the relative amounts of silicic acid and aluminium hydroxide, the reaction time between monosilicic acid and aluminium hydroxide, and the formation of amorphous aluminosilicate. The amount of adsorbed silicic acid and the rate of its polymerization are maximum at pH 9.0–9.5. A part of adsorbed monosilicic acid reacts with aluminium hydroxide to form an aluminosilicate. In an early stage of the polymerization of the adsorbed silicic acid, the polymerization mainly proceeds by the reactions between monosilicic acids and between monosilic...

The use of buccal partitioning as a model to examine the effects of aluminium hydroxide gel on the absorption of propranolol.

Abstract: 1 A buccal partitioning model showed no absorption interaction between propranolol and aluminium hydroxide gel in three volunteer subjects. 2 The previously reported in vivo interaction is therefore not due to propranolol adsorption to, or complexation with the antacid but is more probably due to a decreased gastric emptying rate caused by the antacid. 2 Buccal partitioning has proved useful in the examination of the mechanism of the propranolol/aluminium hydroxide absorption interaction and may also be a suitable in vivo bioavailability screening model for other drugs which can be partitioned in the buccal membranes.

Effect of food on antacid neutralizing capacity in man.

Abstract: In order to estimate their in-vivo reactivity two antacids of equal theoretical neutralizing capacity (approximately 3.9 mol/l at pH 3.5) but of different chemical composition were employed as intragastric titrant (pH 3.5) following a liquid protein meal (oxo) in two groups of five volunteers each. The two antacids chosen (alucol and Camalox) contain different amounts of aluminium hydroxide, magnesium hydroxide and Camalox in addition contains calcium carbonate. The intragastric consumption of these two antacids was much higher than their respective theoretically available neutralizing capacity (Alucol 3.9 times, Camalox 2.4 times). In-vitro studies demonstrated that interaction with oxo reduced the neutralizing capacity of the two antacids at pH 3.5 from 3.9 mol/l to 1.7 mol/l (Alucol) and 2.5 mol/l (Camalox). This potency loss was related to the aluminium hydroxide content of the two antacids. This study indicates that the neutralizing capacity of antacids is not predictable from their reactivity in aqueous solution and is markedly reduced by protein-containing foods.

A method for recovering useful products from waste products obtained when manufacturing aluminium fluoride

Abstract: The invention relates to a method for recovering useable products from waste products deriving from the manufacture of aluminium fluoride on the basis of aluminium hydroxide and fluosilicic acid. Silica contaminated with fluorine and aluminium and obtained in the manufacture of aluminium fluoride is dissolved with a strongly basic hydroxide, whereafter the first solution obtained is mixed with a second solution, obtained by dissolving aluminium hydroxide with a strongly basic hydroxide, and with waste mother liquor and optionally also washing water from the manufacture of aluminium fluoride, in such proportions that the pH-value of the mixture is from about 10-14. The silicate content of the waste products supplied is precipitated as a silicoaluminate, which is separated off, preferably by filtration, for optional further treatment or for direct use, whereafter fluorine, when present in the waste products, is recovered from filtrate by further precipitation, and whereafter the filtrate is passed to a recipient or utilized, for example, as process water in other processes. The fluorine content can be recovered from the filtrate by adding thereto an aluminium compound in an amount sufficient to precipitate out substantially all the fluorine contained in the filtrate as a fluoroaluminate respectively, which is then separated off.

Manufacture of antacid substance

Abstract: The present invention provides a process for the preparation of an antacid material based upon magnesium aluminium hydroxide, wherein magnesium hydroxide and/or magnesium oxide is reacted in an atomic ratio of magnesium to aluminium of 1:1 to 3:1 with an aqueous solution of aluminium sulphate until the pH of the reaction mixture is from 4.0 to 8.0, whereafter water-soluble components are removed from the mixture in known manner and this is isolated and, if desired, dried. The present invention also provides pharmaceutical compositions containing an antacid material prepared by this process, in admixture with a conventional pharmaceutical adjuvant. Furthermore, the present invention provides a method of combating hyperacidity and gastrointestinal diseases, which comprises administering an antacid material prepared by the above process.

Anti-plating agent for one-side hot-dip plating process

Abstract: Disclosed is an anti-plating agent for use in hot-dip plating process, having the following two kinds of composition. The composition of the first kind includes an alkali silicate; boric acid, and alkali hydroxide, magnesia and/or magnesium hydroxide, titania and/or titanium hydroxide, and at least one compound selected from a group consisting of alumina, aluminium hydroxide and alumina zol. The composition of the second kind includes an alkali silicate, boric acid, alkali hydroxide, magnesia and/or magnesium hydroxide, alumina and/or aluminium hydroxide, and at least one kind of titanium oxide and titanium complex oxide and/or at least one kind of zirconium oxide and zirconium complex oxide. These anti-plating agents have a good anti-plating effect and permit an easy separation of the coating film and, hence, can suitably be used in one-side hot-dip plating of steel sheets.

Process for the preparation of an inorganic liquid aqueous floculating agent.

Abstract: The process serves for the preparation of a liquid, aqueous and inorganic flocculating agent based on aluminium hydroxy chlorides by reaction of an aluminium salt with a basifying reagent. To this end, an aqueous, acidic aluminium chloride solution is mixed with an aqueous aluminium sulphate solution with stirring and this mixture is allowed to stand for 6-12 or 24 hours. Sodium metasilicate and/or an aqueous ammonia solution and/or a 50 % strength sodium hydroxide solution are then added to this mixture at room temperature with vigorous stirring always in such a manner that no aluminium hydroxide is precipitated.

A thermal study of the precipitates formed in ammonia neutralization of acidic solutions of dissolved phlogopite

Abstract: The precipitates containing mainly iron, aluminium and magnesium hydroxides, obtained from phlogopite dissolved in nitric acid by means of the neutralization procedure with ammonia, have been investigated by thermal analysis (TG, DTG and DTA). According to the present study, which is part of a larger investigation into the chemical utilization of Finnish mica minerals, the formation of solid solutions between iron and aluminium hydroxides in silt increases with an increasing neutralization temperature. Nitrogen exists mainly in the form of nitrate in silts, and magnesium forms mixed hydroxides with aluminium, which causes a separation between the iron hydroxide and magnesium aluminium hydroxide phases.

GELS IN THE SYSTEM CaO-Al2O3-SiO2 PREPARATION AND STRUCTURAL EVOLUTION

Abstract: Gels in the system CaO-Al2O3-SiO2 were prepared by the sol destabilization method. Aqueous solutions of calcium and aluminium nitrate were added to a colloidal silica solution. In order to avoid a selective precipitation of calcium and aluminium hydroxide, the gelation was done at definite pH. The ranges of gel formation in the binary systems Al2O3-SiO2 and CaO-SiO2 have been established. They lie from 100 to 75 mole % SiO2 and from 100 to 25 mole % SiO2 respectively. The range of formation in the ternary system CaOAl2O3-SiO2 was displaced towards the compositions rich in calcium and gels containing up to 75 mole % CaO were prepared. The gelation time was reduced by calcium ions while the aluminium ions increased it. The structural evolution of these gels were followed as a function of temperature by X-ray diffraction. Calcium nitrate crystals occured at low temperature and decomposed as the temperature increased. This decomposition was facilited in the composition domain rich in aluminium.

Desorption of atropine sulphate and hyoscyamine hydrobromide by various antacids in vitro.

Abstract: Desorption of atropine sulphate and hyoscyamine hydrobromide by antacids such as magnesium trisilicate, magnesium oxide, aluminium hydroxide an bismuth carbonate was carried out i vitro. This was achieved by preparing a complex of the alkaloids with bromothymolblue and then partitioning th complex between aqueous buffer phase and non-aqueous chloroform phase. The latter was analyzed colorimetrically. The desorption followed the sequence: magnesium trisilicate greater than bismuth carbonate greater than aluminium hydroxide greater than magnesium oxide. The results also show that desorption is dependent on the amount of alkaloid adsorbed and the pH of the medium.