No abstract available

[en] A method has been developed for the production of alumina for Advanced Ceramics through the synthesis of ammonium aluminum sulphate. A concentrated commercial ammonium hydroxide were used. The yield of the synthesis process was determined by the titration curves. The characterization of the synthesis products was carried out by X-ray diffraction, differential thermal analysis and particle size distribution. After the calcination of ammonium aluminum sulphate and the obtainment of alumina, test bodies were made, sintered at 1650 deg C, and then their ceramical properties were determined and compared against those of reference commercial alumina. (author)

[en] An investigation was made of the effects of modulation frequency and rf ENDOR power on the single and double quantum ENDOR spectral lines of ⁵³Cr³⁺ ions in single crystals and powders of CsAl sulfate alum. Measurements were made of the linewidths and intensities in the single crystals and of the linewidths in the powders. It was found in the single crystals that a factor of 2/1 exists for the ratio of single/double quantum linewidths at the limit of zero ENDOR power and modulation frequency. Interpretation of the line intensity results with the results of lineshape theory indicates that the ENDOR lines are of Lorentzian form, at least for low values of ENDOR power. (auth)

[en] The efficiency of aluminium sulphate obtained from venezuelan bauxite as coagulant for water treatment was studied. The results show an average 15% aluminium content expressed as Al₂O₃ and 1.4% iron content as Fe₂O₃. The efficiency was similar to that of an iron free analytical grade aluminium sulphate. The significant content of iron found means an additional component that can participate in the coagulation flocculation process; hence the known coagulation properties of iron as a metallic coagulant. The results obtained confirm the iron role in the process and further research, using higher iron contents in the order of 2 percent and more, are proposed to obtain a quantitative evaluation of the participation of this element in the coagulation process. The results can contribute to evaluate the current regulations concerning quality control of the product for use in drinking water

[en] It is well known that sulphuric acid decomposition of aluminosilicate ores produces sulphate compounds of aluminium, iron, calcium, sodium and others. In the case of nepheline syenites, a multicomponent system Al₂SO₄-Na₂SO₄-K₂SO₄-Fe₂(SO₄)₃-H₂O can be considered. In the case of nitric acid decomposition, the system Al(NO₃)₃-NaNO₃-KNO₃-Fe(NO₃)₃-H₂O is considered. These systems are not fully studied due to their multi-component nature.

[en] Crystalline Al₂(SO₄)₃ x 9 H₂O has been synthesized by thermal dehydration of a higher hydrate at a constant total water vapor pressure of one atmosphere. X-Ray diffraction analysis shows the compound to be identical to its only previous preparation by crystallization from solution. The pentahydrate of aluminum sulfate was also synthesized using the dehydration technique. Its X-ray diffraction pattern has been determined for the first time. Doubt is cast upon the existence of the hexahydrate. The rate of vapor rehydration for both Al₂(SO₄)₃ x 9 H₂O and Al₂(SO₄)₃ x 5 H₂O was measured. Al₂(SO₄)₃ x 9 H₂O is metastable under the conditions employed. (orig.)

[en] Monodisperse aluminum hydroxide coated polystyrene (PS) microspheres and their array in large scale was prepared at one step in aqueous solution. The coated PS microsphere arrays are highly ordered and have remarkable structural stability. The arrays can be in plate form and hollow sphere form, depending on the concentration of aluminum sulfate. Hollow aluminum hydroxide shell arrays can be also obtained with calcination

[en] Yellow mini-chrysanthemums were irradiated in a Cobalt-60 Gammacell at the dose of 900 Gy (467 Gy/h) one day after harvest. Samples of 50 flowers, partially opened buds were used to estimate the flower viability. Aluminum sulfate and 8-hydroxyquinoline sulfate were used as two preservative solutions aiming to protect the cut flowers. Our results indicated that the stem immersion in the preservative solutions before and after the irradiation treatment was an efficient procedure, stimulating the flowers development and maintaining the vase-life almost as long as the controls. The present work concludes that it would be possible to use preservative solutions to minimize the damaging effects of the ionizing radiation on chrysanthemum cut flowers, maintaining at the same time the disinfestation action of radiation processing. (author)

[en] In this chapter the chemical and technological bases of processes based on three- and multi-component systems with participation of aluminum, iron and other compounds are considered, which is the basis for the development of individual stages of the technological process of processing aluminum-containing ores.

[en] The article presents a comparative assessment of coagulating ability of aluminum sulfate with a mixed alumina-iron-containing coagulant obtained by the interaction of kaolin clays of the Chashma-Sang deposit with hydrochloric acid. (author)