Showing papers on "Aluminium hydroxide published in 1974"

Osteomalacia due to phosphate depletion from excessive aluminium hydroxide ingestion.

Abstract: therefore result from defective transport of HVA owing to the raised free tryptophan levels rather than to abnormal brain dopamine metabolism. Investigations on brain tissue are required to decide this question. We had hoped that this study would elucidate the arousal effect of levodopa seen in hepatic coma. The results have shown that this cannot be attributed to defective brain dopamine synthesis, but whether it is due to the flushing away of false neurotransmitters accumulating in the brain in liver failure requires further study (Fischer and Baldessarini, 1971). Conceivably the raised plasma free tryptophan levels are important in the mechanism of the cerebral impairment in hepatic encephalopathy in view of the reported toxic effects of tryptophan in the presence of defective liver function.

Studies on recrystallised aluminium hydroxide precipitates

Abstract: Aluminium hydroxide gels were recrystallised in high pH solution for 2–1000 h to give a series of Gibbsite powdersP11/2,P11/8,P1/48,P11/360 andP11/X, consisting of hexagonal platelet crystals; their average platelet lengths (l 0) were 0.03, 0.06, 0.13, 0.26 and 0.45 microns. The dissolution of dilute suspensions of these powders in well-stirred sodium hydroxide solutions were studied at 20–65°C Reaction solid and solution were analysed after different times by chemical and physical methods. Reaction occurred by two-directional dissolution of the platelet crystals. The reactions of GibbsiteP11/X (prepared by prolonged 1000 h crystallisation) were first order w.r.t. powder weight (and second order w.r.t. powder effective surface area); the reactions of the other Gibbsites were first order for the first twenty percent rapid dissolution and then slower. The initial rate constantsk w1 (h−1) and half-lifest 0.5 (h) for reactions ofP11/2,P11/8,P11/48.P11/360 andP11/X with sodium hydroxide solution of unit mean ionic activity at 20°C were 1.70, 0.9; 0.60, 2.2; 0.22, 5.5; 0.07, 14 and 0.02, 38 respectively. Rate constants increased linearly with the mean ionic activity of the hydroxide solution and increased exponentially with reciprocal absolute temperature, four to five times for 15°C temperature rise. Half-lifes decreased in a similar manner. Energies of activation varied from 76–83 kJ/mol. The rates of dissolution are determined by the rate of the chemical reaction between adsorbed hydroxyl ions and adjacent reactive aluminium hydroxide sites on the powder crystal surface.

Crystallisation of gelatinous aluminium hydroxide

Abstract: The gelatinous precipitates from aqueous aluminium chloride solution on the addition of alkalies at various pH have been aged in the mother liquors for a given period of time. The resulting materials have been examined by X-ray diffraction studies. In addition, the changes in the pH value of the mother liquor and the amount of aluminium dissolved in the mother liquor during ageing have been checked under various conditions. As a result, it is found that the freshly precipitated gelatinous aluminium hydroxide exists in an amorphous type independently of the pH value and goes to pseudoboehmite by ageing, but the amount of aluminium dissolved in the mother liquor increases with rising pH value. By further ageing, however, hydrargillite is produced in contact with the aqueous medium at low pH, and bayerite at higher pH. It is concluded that the crystallisation of gelatinous aluminium hydroxide precipitates aged with an aqueous medium occurs in the process and the presence of alkali plays an important role in promoting these transformations.

Process for the recovery of pure alpha-bisabolol

Abstract: α- Bisabolol of plant origin is purified by being treated with alkali hydroxide, alkali alcoholate, alkali carbonate, alkali bicarbonate, alkaline earth hydroxide, alkaline earth oxide or aluminium hydroxide. Preferably activated carbon is also used in the purification. Preferably the α-bisabolol is treated with pure nitrogen gas before the alkali treatment.

The nature of pseudoboehmite and its role in the crystallisation of amorphous aluminium hydroxide

Abstract: Pseudoboehmite samples were prepared by ageing the amorphous hydroxide obtained by the hydrolysis of aluminium s-butoxide using water or aqueous ethanol. Further ageing resulted in the formation of a mixture of crystalline trihydroxides. The two re-crystallisation stages are accompanied by similar but opposite changes in the volume of the aqueous suspension but pseudoboehmite can only be identified by X-ray diffraction in a separated xerogel. Crystallinity of the latter was shown to be enhanced by preparation in 80% ethanol but at concentrations providing only a little more than the water needed for hydrolysis of the alkoxide a new modification of pseudoboehmite was observed. X-ray line broadening and displacement indicated that it possessed an even greater degree of lattice strain than exists in the common form. The composition and specific surface of a number of pseudoboehmite xerogels suggest that the major part of the water, in excess of that in the basic structures AlOOH, is present in a surface monolayer with a minor amount responsible for lattice strain.

水酸化鉄(iii),水酸化アルミニウム沈殿によるヒ素(v),ヒ素(iii),アンチモン(iii)の共沈

Abstract: Coprecipitation behaviors of As(III), (V)and Sb(III)ions onto Fe(III)or aluminium hydroxide in both buffer solutions and sea water have been. studied. lt was found that As(V)and Sb(III)ions are quantitatively. coprecipitated on Fe(III)hydroxide from pH 6 to 9, and As(III)from pH 7 to 9. Coprecipitation Qnto aluminium hydroxide was quantitative for As(V)in the pH range from 5 to 9 b qt not for As(III) In sea water, almost he same behaviors in the buffer solution were obgerved for these three ions, except the fact that the coprecipitation of As(III), (V)became quantitative in the alkalione so1ution( pH 10)where the coprecipitation onto Mg hydrQxide took place. As a conclusion, these three ions tend to be removed into the sediment in the, hyd, rosp. here by the, coprecipitation process.