Showing papers on "Aluminium hydroxide published in 1980"

Kinetics of decomposition of hydrogen peroxide on Fe(III)−Al(III) hydroxide-oxide systems

Abstract: The kinetics of decomposition of hydrogen peroxide have been studied on mixed Fe(III)−Al(III) hydroxide and oxide catalysts. While iron hydroxide possesses considerable catalytic activity, aluminium hydroxide has very little activity. The rate of decomposition on mixed hydroxides increases with increasing concentration of aluminium hydroxide up to about 1.5 mol% and decreases thereafter. The mixed oxides possess negligible activity compared to the corresponding hydroxides. The energy of activation, as calculated from the Arrhenius equation, is 10.1 kcal/mol for sample S4, containing 1.52 mol% of alumina. The rate of decomposition of S4 increases with increasing pH up to 6.8 and decreases thereafter. The rate is first order in all these cases. A suitable mechanism is suggested.

Die Bildung von kristallinem Böhmit in gemeinsam gefällten AlFe(III)-Hydroxiden unter hydrothermalen Bedingungen

Abstract: Under mild hydrothermal conditions originally amorphous aluminium hydroxide coprecipitated with iron(III)ions as Al0,5Fe0,5(OH)3 transforms into aluminium hydroxide crystalline phases which are not observed in products of ageing of pure aluminium hydroxide. By X-ray diffraction analysis, IR spectroscopic studies and microscopic observations it has been found that due to the presence of iron(III) hydroxide it is possible to stabilize the trihydoxide of aluminium i.e. bayerite until 130–140°C. Moreover, with increasing temperature well crystallized boehmite is obtained instead of the usually formed pseudoboehmite. Experiments revealed that the formation of crystalline boehmite does not take place as a process of pseudoboehmit crystallites growth but only as a result of bayerite→boehmite transformation.

Comparison of the effects of cholestyramine and aluminium hydroxide on the biliary bile acid excretion in rats. An experimental model for the depletion of bile acids in bile.

Abstract: Bile flow and biliary excretion of dihydroxy- and trihydroxy-bile acids have been determined in control, cholestyramine (250--2000 mg/kg p.os)- and aluminium hydroxide (250--2000 mg/kg p.os)-pretreated rats. Cholestyramine proved to be a more potent bile acid depleting agent than aluminium hydroxide. The depressing effect of cholestyramine on bile flow was also more significant than that of aluminium hydroxide. Cholestyramine-pretreatment seemed to be a suitable experimental model for the depletion of bile acids in rat bile.

Method of producing crystalline sodium aluminum phosphate

Abstract: In the production of SALP tetrahydrate wherein sodium carbonate and aluminium hydroxide are added to aqueous phosphoric acid, the viscous reactive mixture is agitated with water to free the SALP tetrahydrate crystals from the gelatinous matrix. The crystals are recovered by filtration or centrifugation.

Effects of aluminium hydroxide on restraint-induced and restraint delay-induced gastric ulceration in rats

Abstract: Rats given aluminium hydroxide after cold-restraint stress but before the ‘post-stress delay’ period, ulcerated significantly less severely and less frequently than rats given the drug before cold-restraint stress or those given water at either time period. Both aluminium hydroxide treated groups exhibited less ulceration than non-drug groups. These data suggest profound parasympathetic and hence, gastric acid, involvement in restraint delay-induced ulceration in rats.

Die durch die Anwesenheit von Eisen(III)-ionen bedingten Phasengleichgewichte kristalliner Aluminiumhydroxide des Nordstrandits, Hydrargillits und Bayerits

Abstract: The investigation of ageing processes of coprecipitated aluminium and iron hydroxides—Al0,5Fe0,5(OH)3, initially amorphous, reveals the major influence of Fe3+-ions on the transformation steps among the aluminium hydroxides. By combined X-ray and IR examination it has been found that the ageing of amorphous aluminium hydroxide in the presence of iron ions leads to the surprising coexistence of all known, well defined crystalline trihydroxide species of aluminium, namely nordstrandite, gibbsite and bayerite. Iron ions for their part transform from amorphous stage of hydroxide at the beginning into hydrohematite. The change in temperature orpH conditions of the milieu, or the change of both the parameters results in only one or two modifications from those aluminium hydroxides mentioned above.

Preparation of adsorbent and absorbent agent

Abstract: PURPOSE:To obtain an adsorbent and absorbent agent which simultaneously adsorbs or adsorbs and oxidizes heavy methals or organic substance such as various dyestuff and the like contained in liquid by sintering the reaction product which is obtained by mixing potassium hydroxide into aluminium containing sulferic acid solution. CONSTITUTION:An aqueous potassium hydroxide solution is blended to an aluminium containing sulfuric acid solution and the pH is adjusted to 4.5-9.0 to prepare simultaneously potassium sulphate and aluminium hydroxide, thereafter the reaction product is sintered at a temperature above 100 deg.C after molding or without molding. Further, if an electrolyte substance is simultaneously blended to, preferably at a pH between 3.5-5.5, and thereafter potassium hydroxide is blended at the time when potassium hydroxide is blended to an aluminium containing sulfuric acid solution or firstly aluminium containing sulfuric acid solution is partly neutralized by an alkaline solution other than potassium hydroxide and thereafter potassium hydroxide is blended to prepare the reaction products before molding and sintering, a high strength adsorbent and absorbent agent is obtained.

Thermal Transformation of Aluminium Hydroxide to Alumina

Abstract: The thermal transformation of crystalline and gelatinous aluminium hydroxide by thermogravimetry (TG), differential thermal analysis (DTA), X-ray diffraction study and infrared spectrophotometry.

Preparation of solutions of basic aluminium nitrate

Abstract: A process for the preparation of stable, liquid aqueous solutions of basic aluminium nitrate (aluminium oxynitrate) suitable for spinning into fibres, if desired after incorporation of a polymeric spinning aid, which process comprises reacting an aluminium oxide with nitric acid at below 25° C. to form aluminium hydroxide, optionally washing the precipitate to remove undesirable ions, e.g. sodium ions, and digesting the precipitate in nitric acid or aluminium nitrate. Preferably the solution contains aluminium ions and nitrate ions in the molar ratio 1.6:1 to 2:1. Silica may be incorporated in the solution by reacting it with the nitric acid, together with the aluminium oxide, in the first step of the process.

A method of obtaining alumina from clay and other alumino-silicates and alumina obtained by this method

Abstract: A method of obtaining alumina from clay or other alumino-silicate comprises the step of reacting the clay or other aluminium silicate with a salt of an alkali metal or ammonia, the reaction being carried out in the dry state at a temperature between 300-750°C and for a time between 45 and 120 minutes to produce a double salt of aluminium-alkali or aluminium-ammonium. The double salt is then separated from the reaction product by dissolution, and thereafter the aluminium is precipitated as aluminium hydroxide, which is calcined to give crystalline alumina.