HYDROPHOBICITY OF SILOXANE SURFACES IN SMECTITES AS REVEALED BY AROMATIC HYDROCARBON ADSORPTION FROM WATER
HYDROPHOBICITY OF SILOXANE SURFACES IN SMECTITES AS REVEALED BY AROMATIC HYDROCARBON ADSORPTION FROM WATER
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DOI：
10.1346/ccmn.1991.0390412
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发表时间：
1991-08-01
影响因子：
2.2
通讯作者：
BOYD, SA
中科院分区：
文献类型：
--
作者：
JAYNES, WF;BOYD, SA
通过测量有机粘土对水中芳香烃的吸附，研究了蒙脱石中硅氧烷表面的性质。 有机粘土是通过用小的疏水性有机阳离子三甲基苯铵（TMPA）取代一系列蒙脱石的亲水性无机交换阳离子来制备的。 使用不同电荷密度的蒙皂石，导致有机粘土中的 TMPA 含量不同。 TMPA-蒙脱石对水中苯、烷基苯和萘的吸附等温线表明，吸附与 TMPA 含量成反比。 等温线的朗缪尔形式表明芳香族化合物吸附到粘土表面。 TMPA-蒙脱石中可能的吸附位点仅限于 TMPA 阳离子和硅氧烷氧表面。 由于吸附随着层电荷和 TMPA 含量的减少而增加，因此有机化合物必须吸附到硅氧烷表面。基于吸附化合物单层（通过将吸附数据拟合到 Langmuir 方程来估计）和每种 TMPA-粘土的 N2 比表面积的计算表明，每个吸附分子占据的表面积随着有机化合物的平面面积的增加而增加。 分子增加。 这强烈表明化合物的平面直接吸附到粘土表面。 显然，TMPA 阳离子的作用是保持蒙脱石夹层开放。 相对的层间粘土表面上的 TMPA 阳离子的苯基之间的相互作用可能会增加吸附区域的尺寸。 这些结果表明，如果亲水性无机交换阳离子被小的疏水性有机阳离子取代，蒙脱石的硅氧烷表面可以有效地从水中吸附芳香烃。 疏水性有机分子从水中的强烈吸附证明了蒙脱石中硅氧烷表面的疏水性。
The nature of the siloxane surface in smectites was investigated by measuring the adsorption of aromatic hydrocarbons from water by organo-clays. The organo-clays were prepared by replacing the hydrophilic, inorganic exchange cations of a series of smectites with the small, hydrophobic organic cation, trimethylphenylammonium (TMPA). Smectites with a range in charge densities were used that resulted in different TMPA contents in the organo-clays. Adsorption isotherms of benzene, alkylbenzenes, and naphthalene from water by the TMPA-smectites indicated that sorption was inversely related to TMPA content. The Langmuir form of the isotherms suggests that the aromatic compounds adsorb to the clay surface. Possible adsorptive sites in TMPA-smectites are limited to the TMPA cations and the siloxane oxygen surfaces. Because sorption increased as layer charge and TMPA content decreased, the organic compounds must adsorb to the siloxane surfaces.Calculations based on an adsorbed compound monolayer, which was estimated by fitting adsorption data to the Langmuir equation, and the N2 specific surface area of each TMPA-clay, indicate that the surface area occupied by each adsorbed molecule increases as the planar area of the molecule increases. This strongly indicates that the planar surfaces of the compounds adsorb directly to the clay surface. Apparently, the TMPA cations function to keep the smectite interlayers open. Interactions between the phenyl groups of TMPA cations on opposing interlayer clay surfaces may act to increase the size of the adsorptive regions. These results show that the siloxane surfaces of smectites can effectively adsorb aromatic hydrocarbons from water if the hydrophilic, inorganic exchange cations are replaced with small, hydrophobic organic cations. The strong adsorption of hydrophobic organic molecules from water demonstrates the hydrophobicity of the siloxane surfaces in smectites.