硅藻土合成片状托贝莫来石及其机理研究

以硅藻土为硅质原料,采用动态水热法合成了具有良好片状结构的托贝莫来石,并研究了原料中铝组分及十二烷基硫酸钠（SDS）对产物形貌的影响及其机理。结果表明：在合成温度为200 ℃、时间为6 h、液固比为20 mL/g、SDS添加量为2.4%、搅拌转速为160 r/min条件下,可以合成出片状结构良好的托贝莫来石产物;以纯二氧化硅为硅源作为对比,当硅藻土作为硅源时,硅藻土中的含铝组分是片状托贝莫来石生成的主要因素之一;铝原子可通过对桥联四面体中硅原子的取代阻碍硅氧四面体双链的生成,进而促使晶体向片状的晶形生长;此外,十二烷基硫酸钠作为一种阴离子型表面活性剂,可与托贝莫来石（001）晶面的H—O发生键合,阻碍晶体在（001）晶面的生长,对片状晶形的生长同样具有促进作用。

Research on synthesis of flaky tobermorite from diatomite and its mechanism

Using diatomatomite as siliceous raw materials,tobermorite with lamellar structure was synthesized by dynamic hydrothermal method.In addition,the influences of the aluminum content in the raw materials and the sodium dodecyl sulfate（SDS） on the morphology of the products were investigated.The results showed that under the conditions of synthesis tempera-ture of 200 ℃,time of 6 h,liquid-solid ratio of 20 mL/g,SDS addition amount of 2.4% and stirring speed of 160 r/min,the tobermorite product with good lamellar structure was prepared. Based on the comparative experiments using pure SiO₂ as the silicon source,it was found that aluminum impurities in the diatomite was one of the main factors for the formation of flakye tobermorite.The substitution of aluminum atoms for silicon atoms in bridged tetrahedra prevented the formation of silicon-oxygen tetrahedron double chained and promoted the growth of crystals into plate-like crystal forms.On the other hand,the sodium dodecyl sulfate,as an anionic surfactant,could bond with the H—O on the（001） crystal plane of tobermorite,hinder-ing the growth of crystals on the（001） crystal plane and promoting the growth of flaky crystal form as well.