Wu Zhijian, You Laijiang, Xiang Hong, Jiang Yan
Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, China.
J Colloid Interface Sci. 2006 Nov 15;303(2):346-52. doi: 10.1016/j.jcis.2006.08.018. Epub 2006 Aug 17.
Without using any templating agents, mesoporous hybrid gels were prepared using mixtures of tetraethoxysilane (TEOS) with n-propyltriethoxysilane (PTES), bis(trimethoxysilyl)hexane (TSH), or bis(trimethoxysilylpropyl)amine (TSPA) as precursors. Fourier transform infrared (FTIR), N2 adsorption/desorption, thermogravimetry (TG), point of zero charge (PZC), and water vapor adsorption measurements were used to characterize the gels. The adsorption of methyl orange (MO), methyl red (MR), bromocresol purple (BP), phenol red (PR), neutral red (NR), and brilliant blue FCF (BBF) by the gels in both 0.01 M HCl and 0.01 M NaOH solutions was compared comprehensively. The gel derived from TEOS/TSH (with -(CH2)6- groups, Gel 2) has the largest specific surface area (695 m2 g(-1)), the smallest pore volume (0.564 cm3 g(-1)), and the smallest average pore size (3.7 nm). The gels derived form TEOS/PTES (with -(CH2)2CH3 groups, Gel 1), and TEOS/TSPA (with -(CH2)3NH(CH2)3- groups, Gel 3) have similar textual properties. The PZC of Gels 1, 2, and 3 was estimated to be 6.28, 6.20, and 6.88, respectively. Gel 3 has the highest PZC due to the presence of -NH- groups. In general, Gel 2 shows the highest dye adsorption among all the gels in both acidic and basic solutions. All the dyes except NR have much lower adsorption in basic solutions than in acidic solutions. In acidic solutions Gels 1 and 2 have similar adsorption trends for the dyes, except for BP, with NR having the highest adsorption, and PR the lowest adsorption. Gel 3 presents a different trend from Gels 1 and 2, with BBF having the highest adsorption, and MR the lowest adsorption. In basic solutions the order of dye adsorption by all the gels is shown to follow the sequence NR>>MR approximately BBF>MO>BP approximately PR. The adsorption results can be explained by considering the textural properties of the gels and the interactions between the gel surfaces and the dyes, which include hydrogen bonding, electrostatic, and hydrophobic interactions.
在不使用任何模板剂的情况下，以四乙氧基硅烷（TEOS）与正丙基三乙氧基硅烷（PTES）、双（三甲氧基硅基）己烷（TSH）或双（三甲氧基硅基丙基）胺（TSPA）的混合物为前驱体制备了介孔杂化凝胶。采用傅里叶变换红外光谱（FTIR）、N₂吸附/脱附、热重分析（TG）、零电荷点（PZC）和水蒸气吸附测量等方法对凝胶进行了表征。全面比较了凝胶在0.01 M HCl和0.01 M NaOH溶液中对甲基橙（MO）、甲基红（MR）、溴甲酚紫（BP）、酚红（PR）、中性红（NR）和亮蓝FCF（BBF）的吸附情况。由TEOS/TSH（含-(CH₂)₆-基团，凝胶2）衍生的凝胶具有最大的比表面积（695 m² g⁻¹）、最小的孔体积（0.564 cm³ g⁻¹）和最小的平均孔径（3.7 nm）。由TEOS/PTES（含-(CH₂)₂CH₃基团，凝胶1）和TEOS/TSPA（含-(CH₂)₃NH(CH₂)₃-基团，凝胶3）衍生的凝胶具有相似的结构性质。凝胶1、2和3的PZC分别估计为6.28、6.20和6.88。由于存在-NH-基团，凝胶3具有最高的PZC。总体而言，在酸性和碱性溶液中，凝胶2在所有凝胶中表现出最高的染料吸附量。除NR外，所有染料在碱性溶液中的吸附量均远低于酸性溶液。在酸性溶液中，凝胶1和2对染料具有相似的吸附趋势，但BP除外，其中NR的吸附量最高，PR的吸附量最低。凝胶3呈现出与凝胶1和2不同的趋势，BBF的吸附量最高，MR的吸附量最低。在碱性溶液中，所有凝胶对染料的吸附顺序为NR>>MR≈BBF>MO>BP≈PR。吸附结果可以通过考虑凝胶的结构性质以及凝胶表面与染料之间的相互作用来解释，这些相互作用包括氢键、静电和疏水相互作用。
