正丁醇/水混合溶剂中一步合成NO3-LDH的研究

以尿素为沉淀剂,正丁醇/水混合液为溶剂,采用水热法直接合成层状双金属氢氧化物ZnAl-NO₃-LDHs。通过X射线衍射（XRD）、傅里叶变换红外光谱（FT-IR）、扫描电镜（SEM）和元素分析（CHN）等对所得样品进行表征,证明在尿素存在条件下,NO₃^-进入LDHs层间;XRD、SEM结果和丁达尔现象显示所得NO₃-LDHs可在甲酰胺溶液中剥离。对尿素存在条件下形成NO₃-LDH而非CO₃-LDH的机理进行了探讨。以氯化盐和硫酸盐为原料,采用本文方法成功合成了Cl-LDH和SO₄-LDH,此研究结果可为制备不同阴离子插层的LDHs提供一种简单直接的方法。

The synthesis of nitrate-intercalated layered double hydroxides (NO3-LDH) in n-BuOH/water mixed solvents

ZnAl-NO₃-LDHs have been directly synthesized in an n-BuOH/water system using urea as a precipitating agent via a hydrothermal method. The as-prepared samples were characterized by XRD, FT-IR, SEM, TEM and elemental analysis. The results confirmed that NO₃^- ions had been intercalated into the LDHs interlayer galleries even in the presence of urea. The Tyndall phenomenon, XRD and SEM results showed that the obtained NO₃-LDHs could be delaminated in formamide. The mechanism of the formation of NO₃-LDH rather than the expected CO₃-LDH in the presence of urea has been discussed. Using this method, two other types of LDHs with Cl^-and SO₄^2- anions in the interlayer galleries were also successfully synthesized by using metal chloride salts and metal sulfate salts as starting reagents, respectively. Our findings may provide a cheap and direct way to prepare LDHs with the desired anions in the interlayer galleries.