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International Journal of Soil Science
  Year: 2007 | Volume: 2 | Issue: 4 | Page No.: 247-257
DOI: 10.3923/ijss.2007.247.257
 
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Adsorption of Water on Nano-Ball Allophane as Affected by Dry Grinding

Hamayoon Khan, Naoto Matsue and Teruo Henmi

Abstract:
Water adsorption is one of the important physicochemical properties of clays and nano-ball allophane has extremely high water adsorption capacity due to its high specific surface. The water vapor adsorption on two nano-ball allophane samples with low and high Si/Al ratios (0.67: KyP; 0.99: KnP), under various Relative Humidities (RHs), generally decreased with dry grinding treatment. For KyP sample, water vapor adsorption at monolayer level on the nano-ball (RH≤0.45) decreased by 2 h grinding, but capillary water condensation between the nano-ball (RH≥0.6) was not affected. The little effect of the grinding on the capillary water condensation means no change in water vapor accessibility of outer surface in the hollow spherical allophane structure. On the other hand, decrease in water vapor adsorption at monolayer level indicates decrease in water vapor accessibility of the rest of total surface, i.e., pore region and inner surface of the hollow sphere. In case of KnP sample with higher Si/Al ratio, water vapor adsorption at monolayer level showed little change with the grinding, but capillary water condensation decreased. These results indicates that, with the grinding, allophane nano-balls in the KnP sample became more closer each other, but small space is still remained allowing monolayer water adsorption on the outer surface, pore region and inner surface. The small space remained is presumed to be due to accessorily attached silicate tails projected outward of the nano-ball, which prevented direct contact between nano-balls. The nano-ball in the KyP sample with few tails tended to contact directly even before the grinding and the grinding might caused connection between nano-balls via pore region which decreased water vapor accessibility to pore region and inner surface.
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How to cite this article:

Hamayoon Khan, Naoto Matsue and Teruo Henmi , 2007. Adsorption of Water on Nano-Ball Allophane as Affected by Dry Grinding. International Journal of Soil Science, 2: 247-257.

DOI: 10.3923/ijss.2007.247.257

URL: https://scialert.net/abstract/?doi=ijss.2007.247.257

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