Lenhardt Katharina R, Breitzke Hergen, Buntkowsky Gerd, Reimhult Erik, Willinger Max, Rennert Thilo
Fachgebiet Bodenchemie mit Pedologie, Institut für Bodenkunde und Standortslehre, Universität Hohenheim, Emil-Wolff-Str. 27, 70599, Stuttgart, Germany.
Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt, Alarich-Weiss-Str. 8, 64287, Darmstadt, Germany.
Sci Rep. 2021 Feb 18;11(1):4207. doi: 10.1038/s41598-021-83643-w.
We report here on structure-related aggregation effects of short-range ordered aluminosilicates (SROAS) that have to be considered in the development of synthesis protocols and may be relevant for the properties of SROAS in the environment. We synthesized SROAS of variable composition by neutralizing aqueous aluminium chloride with sodium orthosilicate at ambient temperature and pressure. We determined elemental composition, visualized morphology by microscopic techniques, and resolved mineral structure by solid-state Si and Al nuclear magnetic resonance and Fourier-transform infrared spectroscopy. Nitrogen sorption revealed substantial surface loss of Al-rich SROAS that resembled proto-imogolite formed in soils and sediments due to aggregation upon freezing. The effect was less pronounced in Si-rich SROAS, indicating a structure-dependent effect on spatial arrangement of mass at the submicron scale. Cryomilling efficiently fractured aggregates but did not change the magnitude of specific surface area. Since accessibility of surface functional groups is a prerequisite for sequestration of substances, elucidating physical and chemical processes of aggregation as a function of composition and crystallinity may improve our understanding of the reactivity of SROAS in the environment.
我们在此报告短程有序铝硅酸盐（SROAS）与结构相关的聚集效应，这些效应在合成方案的开发中必须予以考虑，并且可能与SROAS在环境中的性质相关。我们通过在室温和常压下用原硅酸钠中和氯化铝水溶液来合成组成可变的SROAS。我们测定了元素组成，通过显微镜技术观察了形态，并通过固态硅和铝核磁共振以及傅里叶变换红外光谱解析了矿物结构。氮吸附显示富铝SROAS存在大量表面损失，这类似于土壤和沉积物中形成的原伊毛缟石，是由于冷冻时的聚集所致。在富硅SROAS中这种效应不太明显，表明在亚微米尺度上对质量空间排列存在结构依赖性效应。低温研磨有效地破碎了聚集体，但没有改变比表面积的大小。由于表面官能团的可及性是螯合物质的先决条件，阐明作为组成和结晶度函数的聚集物理和化学过程可能会增进我们对SROAS在环境中反应性的理解。
