Walcarius Alain, Ganesan Vellaichamy
Laboratoire de Chimie Physique et Microbiologie pour l'Environnement Unité Mixte de Recherche UMR 7564, CNRS-Université Henri Poincaré Nancy I, France.
Langmuir. 2006 Jan 3;22(1):469-77. doi: 10.1021/la051916s.
Porous silica spheres functionalized with quaternary ammonium groups have been prepared by co-condensation of N-((trimethoxysilyl)propyl)-N,N,N-trimethylammonium chloride (TMTMAC) and tetraethoxysilane (TEOS) in the presence of cetyltrimethylammonium as a template and ammonia as a catalyst. The physicochemical characteristics of the resulting ion exchangers have been analyzed by various techniques and discussed with respect to the amount of organofunctional groups in the materials. For comparison purposes, both an ordered MCM-41 type mesoporous silica and two silica gels of different pore size have been grafted with TMTMAC. The ion-exchange capabilities were first evaluated from batch experiments (determination of anion-exchange capacities) and then by ion-exchange voltammetry at carbon paste electrodes modified with these hybrid materials. Effective concentration of Fe(CN)(6)(3)(-) species in the anion exchangers was pointed out, while no significant accumulation of Ru(NH(3))(6)(3+) was observed. The preconcentration efficiency was discussed on the basis of the organic group content in the materials as well as their structure and porosity. A second series of materials displaying zwitterionic surfaces was finally prepared and characterized with respect to their physicochemical properties and ion-exchange voltammetric behavior. They consisted of sulfonic acid-functionalized mesoporous silica samples resulting from the oxidation of thiol-functionalized silica spheres obtained by co-condensation of mercaptopropyl-trimethoxysilane (MPTMS) and TEOS, which were then grafted with TMTMAC at various functionalization levels. Possible interactions between the ammonium and sulfonate moieties in the confined medium were pointed out from X-ray photoelectron spectroscopy. The competitive accumulation-rejection of Fe(CN)(6)(3)(-) and Ru(NH(3))(6)(3+) redox probes was finally studied by cyclic voltammetry.
通过在十六烷基三甲基氯化铵作为模板和氨作为催化剂的存在下，使N-((三甲氧基甲硅烷基)丙基)-N,N,N-三甲基氯化铵(TMTMAC)和四乙氧基硅烷(TEOS)共缩合，制备了用季铵基团功能化的多孔二氧化硅球。通过各种技术分析了所得离子交换剂的物理化学特性，并就材料中有机官能团的数量进行了讨论。为了进行比较，将有序的MCM-41型介孔二氧化硅和两种不同孔径的硅胶用TMTMAC接枝。首先通过分批实验(阴离子交换容量的测定)评估离子交换能力，然后通过用这些杂化材料修饰的碳糊电极上的离子交换伏安法进行评估。指出了阴离子交换剂中Fe(CN)(6)(3)(-)物种的有效浓度，而未观察到Ru(NH(3))(6)(3+)的明显积累。根据材料中的有机基团含量及其结构和孔隙率讨论了预富集效率。最后制备了第二系列具有两性离子表面的材料，并对其物理化学性质和离子交换伏安行为进行了表征。它们由磺酸功能化的介孔二氧化硅样品组成，这些样品是由巯基丙基-三甲氧基硅烷(MPTMS)和TEOS共缩合得到的巯基功能化二氧化硅球氧化而成，然后在不同的功能化水平上用TMTMAC接枝。通过X射线光电子能谱指出了受限介质中铵和磺酸根基团之间可能的相互作用。最后通过循环伏安法研究了Fe(CN)(6)(3)(-)和Ru(NH(3))(6)(3+)氧化还原探针的竞争性积累-排斥。
