硅藻土原位负载网状纳米结构硅酸镁及其对Cr(Ⅵ)吸附性能

In-Situ Growing Nanostructured Magnesium Silicate on Diatomite: Adsorption Properties of Cr(Ⅵ)

采用MgCl_2·6H_2O作为镁源,NH_3·H_2O作为沉淀剂,十六烷基三甲基溴化铵(CTAB)作为模板剂,以水热法在硅藻土表面原位生长纳米花状Mg(OH)_2,随反应时间增加,转变成单斜晶系网状结构Mg_3Si_4O_(10)(OH)_2纳米花。采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)、氮气吸附-脱附测试、傅里叶红外光谱(FT-IR)、X射线光电子能谱(XPS)等测试手段对样品进行了表征,结果显示:反应时间为0.5～2.0 h时硅藻土表面以生长Mg(OH)_2为主,样品的比表面积为180 m^2·g^(-1);反应时间至3h时,硅藻土表面Mg(OH)_2转化成网状结构Mg_3Si_4O_(10)(OH)_2,样品比表面积增大到350 m^2·g^(-1),此复合结构对Cr(Ⅵ)最大吸附量可达570 mg·g^(-1)。

The nanostructured Mg3Si4O10(OH)2 in situ grown on diatomite were first synthesized via a hydrothermal route.Moreover,Mg(OH)2 nanoflowers were first grown on the surface of diatomite after hydrothermal treatment for 0.5~2 h,these nanoflowers obtained the surface areas of 180 m2·g-1.As the hydrothermal reaction time increasing to 3 h,the Mg(OH)2 nanoflowers were completely transformed to lattice-like structure Mg3Si4O10(OH)2 which possessed the higher surface area of 350 m2·g-1.Mg3Si4O10(OH)2/diatomite composite structure showed a well adsorption performance of 570 mg·g-1 for Cr(Ⅵ).It is firmly believed that the adsorbent has a great significance of removing heavy metal ions in wastewater.