Bartelt-Hunt Shannon L, Burns Susan E, Smith James A
Program of Interdisciplinary Research in Contaminant Hydrogeology, Department of Civil Engineering, University of Virginia, P.O. Box 400742, Charlottesville, VA 22904-4742, USA.
J Colloid Interface Sci. 2003 Oct 15;266(2):251-8. doi: 10.1016/s0021-9797(03)00617-9.
Sorption of three nonionic organic solutes (benzene, trichloroethene, and 1,2-dichlorobenzene) to hexadecyltrimethylammonium bentonite (HDTMA bentonite) and benzyltriethylammonium bentonite (BTEA bentonite) was measured as a function of total organic-carbon content at quaternary ammonium cation loadings ranging from 30 to 100% of the clay's cation-exchange capacity. Sorption of all three solutes to HDTMA bentonite was linear and sorption of all three solutes by the HDTMA bentonite increased as the organic-carbon content of the clay increased. 1,2-Dichlorobenzene sorbed most strongly to HDTMA bentonite, followed by benzene and TCE. The stronger sorption of benzene to HDTMA bentonite compared to TCE was unexpected based on a partition mechanism of sorption and consideration of solute solubility. LogK(oc) values for all three solutes increased with organic-carbon content. This suggests that the increased organic-carbon content alone may not explain the observed increase in sorption capacity. Sorption of the three solutes to BTEA bentonite was nonlinear and solute sorption increased with decreasing organic-carbon content, with a peak in the magnitude of solute sorption occurring at an organic-carbon content corresponding to 50% of CEC. Below 50% of CEC, sorption of all three solutes to BTEA bentonite decreased with decreasing organic-carbon content. Surface area measurements indicate that the surface area of both organobentonites generally decreased with increasing organic-carbon content. Since nonionic organic solute sorption to BTEA bentonite occurs by adsorption, the reduced sorption is likely caused by the reduction in surface area corresponding to increased organic-cation loading.
在季铵阳离子负载量为粘土阳离子交换容量的30%至100%范围内，测量了三种非离子有机溶质（苯、三氯乙烯和1,2-二氯苯）对十六烷基三甲基铵膨润土（HDTMA膨润土）和苄基三乙基铵膨润土（BTEA膨润土）的吸附情况，该吸附情况是总有机碳含量的函数。所有三种溶质对HDTMA膨润土的吸附都是线性的，并且随着粘土有机碳含量的增加，HDTMA膨润土对所有三种溶质的吸附量也增加。1,2-二氯苯对HDTMA膨润土的吸附最强，其次是苯和三氯乙烯。基于吸附的分配机制和溶质溶解度的考虑，苯对HDTMA膨润土的吸附比三氯乙烯更强是出乎意料的。所有三种溶质的LogK(oc)值都随着有机碳含量的增加而增加。这表明仅有机碳含量的增加可能无法解释观察到的吸附容量的增加。三种溶质对BTEA膨润土的吸附是非线性的，溶质吸附量随着有机碳含量的降低而增加，在有机碳含量相当于阳离子交换容量的50%时，溶质吸附量达到峰值。在阳离子交换容量的50%以下，所有三种溶质对BTEA膨润土的吸附量随着有机碳含量的降低而降低。表面积测量表明，两种有机膨润土的表面积通常随着有机碳含量的增加而减小。由于非离子有机溶质对BTEA膨润土的吸附是通过吸附发生的，吸附量降低可能是由于有机阳离子负载量增加导致表面积减小所致。
