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Aluminium Sulphate

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Bruno Delvaux – 1st expert on this subject based on the ideXlab platform

  • direct evidence of basic Aluminium Sulphate minerals in an s impacted andosol
    European Journal of Soil Science, 2005
    Co-Authors: Thomas Delfosse, Francoise Elsass, Bruno Delvaux

    Abstract:

    The formation of basic Aluminium Sulphate (BAS) minerals [(K,Na)(n)Al-x(OH)(y)(SO4)(z)] has often been invoked to explain Sulphate retention in soils. These minerals have not yet, however, been directly observed in the soil. We extracted the clay fractions of Andosols intercepting large inputs of volcanogenic sulphur dioxide and acids (HCl, HF), simply by dispersing clays with Na+-resins in deionized water without any other chemical treatment. Clay fractions concentrate 39-63% of total sulphur content of soil. Transmission electron microscopy coupled with energy-dispersive analysis revealed the presence of BAS particles, appearing as nodules and spheres. These particles have an equivalent diameter smaller than 0.2 mu m. They have an Al:S ratio close to 2.2 and 3.8 and are possibly amorphous aluminite or basaluminite, respectively. They seem to have been formed in microenvironments enriched in Sulphate, but also in fluoride anions. Their formation seems to have been enhanced by the combination of large inputs of acids and SO2 and an effective Al supply from weathering of volcanic glass.

Geoffrey M Evans – 2nd expert on this subject based on the ideXlab platform

  • effect of Aluminium Sulphate on interactions between silica surfaces studied by atomic force microscopy
    Water Research, 2007
    Co-Authors: Bogdan C Donose, Anh V Nguyen, Geoffrey M Evans

    Abstract:

    Surface interaction forces between different types of silica surfaces (pure silica beads, borosilicate glass beads polished silicon wafers and fused silica slides) were measured by atomic force microscopy y (AFM) in solutions of Aluminium Sulphate (alum) in order to understand the role ol hydrated Aluminium species on the coagulation of negatively charged oxide colloids n drinking water treatment. The alum coagulant concentration used in this study wa 3 150 mu M Aluminium. The alum solutions were prepared from analytical grade Al-2(SO4 (3) center dot 16H(2)O. It was found that the presence of Aluminium Sulphate at a concentration close to the values typically used in industrial scale water treatment applications generally induced strong, long-range repulsive forces between the various types of surfaces studies d. At this alum concentration streaming potential measurements indicated reversal in the sign of the surface charge. It was also found that whenever borosilicate glass beads were used, the interaction force became strongly attractive when the AFM cell was flushed with deionised water. It was argued that this attraction occurred because of the charge nonuniformity of the Aluminium hydrates adsorbed at the glass surface. A mechanism was proposed to explain the observed interaction phenomena based on the deduced micros ructure of the adsorbed surface layers and to rationalise the new findings for application in drinking water treatment. (C) 2007 Elsevier Ltd. All rights reserved.

Anh V Nguyen – 3rd expert on this subject based on the ideXlab platform

  • effect of Aluminium Sulphate on interactions between silica surfaces studied by atomic force microscopy
    Water Research, 2007
    Co-Authors: Bogdan C Donose, Anh V Nguyen, Geoffrey M Evans

    Abstract:

    Surface interaction forces between different types of silica surfaces (pure silica beads, borosilicate glass beads polished silicon wafers and fused silica slides) were measured by atomic force microscopy y (AFM) in solutions of Aluminium Sulphate (alum) in order to understand the role ol hydrated Aluminium species on the coagulation of negatively charged oxide colloids n drinking water treatment. The alum coagulant concentration used in this study wa 3 150 mu M Aluminium. The alum solutions were prepared from analytical grade Al-2(SO4 (3) center dot 16H(2)O. It was found that the presence of Aluminium Sulphate at a concentration close to the values typically used in industrial scale water treatment applications generally induced strong, long-range repulsive forces between the various types of surfaces studies d. At this alum concentration streaming potential measurements indicated reversal in the sign of the surface charge. It was also found that whenever borosilicate glass beads were used, the interaction force became strongly attractive when the AFM cell was flushed with deionised water. It was argued that this attraction occurred because of the charge nonuniformity of the Aluminium hydrates adsorbed at the glass surface. A mechanism was proposed to explain the observed interaction phenomena based on the deduced micros ructure of the adsorbed surface layers and to rationalise the new findings for application in drinking water treatment. (C) 2007 Elsevier Ltd. All rights reserved.