Abstract

The mechanism of montmorillonite modification with sodium metasilicate for inversing its ion-exchange characteristics has been studied. The blockage of the interlayer space in montmorillonite by amorphous silicon–oxygen clusters, which are formed as a result of sodium metasilicate hydrolysis, hinders the access of ions to the internal negatively charged surface of the mineral and increases the strength of bonding between aluminosilicate layers. As a result, adsorption becomes possible only on the outer surface of particles, namely, on active silanol and aluminol groups. This fact has been confirmed by the high rate of the process, as well as by the appearance of the ability to adsorb anions only after the reversal of montmorillonite surface charge. The value of the adsorption of Cr(VI) oxoanions by modified montmorillonite has appeared to be 0.26–1.05 mg/g depending on the synthesis conditions of the samples.

中文翻译：

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蒙脱石离子交换特性的反演

摘要

研究了用硅酸钠改性蒙脱土使其离子交换特性逆转的机理。蒙脱石中的层间空间被偏硅酸钠水解而形成的非晶硅-氧簇阻塞，阻碍了离子进入矿物内部带负电荷的表面，并增加了铝硅酸盐层之间的结合强度。结果，仅在颗粒的外表面上，即在活性硅烷醇和铝醇基团上吸附成为可能。该过程的高速率以及仅在蒙脱石表面电荷反转之后才出现吸附阴离子的能力已证实了这一事实。改性蒙脱石吸附Cr（VI）含氧阴离子的值似乎为0。