N2-BET specific surface area of bentonites

被引:132
作者
Kaufhold, S. [1 ]
Dohrmann, R. [1 ,2 ]
Klinkenberg, M. [3 ]
Siegesmund, S. [4 ]
Ufer, K. [5 ]
机构
[1] BGR, D-30655 Hannover, Germany
[2] LBEG, D-30655 Hannover, Germany
[3] Forschungszentrum Julich, Inst Energieforsch Sicherheitsforsch & Reaktortec, IEF 6, D-52425 Julich, Germany
[4] Univ Gottingen, Geowissensch Liches Zentrum, D-37077 Gottingen, Germany
[5] TU Bergakad Freiberg, Inst Mineral, D-09596 Freiberg, Germany
关键词
Bentonite; Specific surface area; Smectites; CATION-EXCHANGE CAPACITY; COMPLEXES; CLAYS; WATER; ION;
D O I
10.1016/j.jcis.2010.05.018
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The specific surface areas (SSA(N2BET)) of 36 different bentonites had larger values for Ca2+/Mg2+ bentonites than for Na+ bentonites. This trend could not be explained by the different d(0 0 1) values nor by the different microstructures. The investigation of Cu-triene-exchanged smectites, which on drying at 105 degrees C still had a d(0 0 1) value accounting for approximately 13 angstrom, proved that the SSA(N2BET) of low-charged smectites increased more than that of high-charged smectites. This could be explained by: (i) more space between the permanent charge sites in the case of low-charged smectites and (ii) the fact that the layers of Cu-triene smectites do not collapse at 105 degrees C. In contrast the SSA(N2BET) of Ca2+-exchanged bentonites could not be related to the layer charge density (LCD) as in the case of the Cu-triene-exchanged bentonites which is probably due to the varying number of collapsed layers. In conclusion, the SSA(N2BET) of bentonites which is known to be largely variable is probably determined by microporosity resulting from the quasi-crystalline overlap region and accessible areas of the interlayer. The number of layers per stack and the microstructure are supposed to play a subordinate role. The larger SSA(N2BET) of Ca/Mg bentonites compared to Na bentonites probably can be explained by the larger space between the charges in the case of the presence of divalent cations.(C) 2010 Elsevier Inc. All rights reserved.
引用
收藏
页码:275 / 282
页数:8
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