单宁为模板水热合成纳米二氧化钛及其对铀的吸附性能

Hydrothermal synthesis of nano-titanium dioxide using tannin as template and its adsorption performances for uranium

摘要:

本文利用单宁可与金属离子形成稳定配合物的性质，以不同的单宁为模板，水热合成了纳米二氧化钛(T-NTO)，用FT-IR，XRD，BET，SEM，TEM对合成的T-NTO的结构及形貌进行表征，并探究其对铀的吸附性能。结果表明，以单宁为模板水热法合成可以明显提高纳米二氧化钛的比表面积，从而提高其吸附容量；所制备的T-NTO对铀有较强的吸附能力，并且以不同单宁为模板制备的T-NTO对铀（UO22+）的吸附容量存在明显差异，杨梅单宁为模板合成的纳米二氧化钛(BT-NTO)粒径最小，比表面积达到96.61 m2／g；T-NTO对铀的吸附等温线符合Langmuir方程，BT-NTO在318K时对铀的吸附容量高达0.7054 mmol／g；而吸附动力学符合准二级动力学方程，吸附速率较快；共存阳离子Zn2+、Mg2+、Pb2+、Cu2+、Mn2+、Na+及共存阴离子Cl-、SO42-、CO32-对BT-NTO吸附铀的影响很小，而F-的影响较大，但可通过引入Al3+来减小F-的影响。解吸实验表明, 0.1 mol／L的HNO3溶液可使吸附的铀解吸下来，BT-NTO可多次重复使用。

Abstract:

In this work, nano-titanium dioxide (T-NTO) was prepared by hydrothermal synthesis using tannins as template. The structure and morphology of T-NTO were characterized by FT-IR, XRD, BET, SEM, TEM, and its adsorption performances for uranium were investigated. The results show that the specific surface area of T-NTO was significantly increased，and the adsorption capacity of the T-NTO exhibits obvious different varying with different tannins as template. It was found that the nano-titaniumdioxide (BT-NTO) prepared using bayberry tannin as template has the smallest particle size and its specific surface area is up to 96.61 m2／g. Furthermore, the adsorption process of uranium by T-NTO can be described by the Langmuir isothermal model and pseudo-second-order kinetic equation, and the adsorption capacity of BT-NTO to uranium is attained to 0.7054 mmol／g at 318K. In addition, the coexisting ions, including Zn2+, Mg2+, Pb2+, Cu2+, Mn2+, Na+, Cl-, SO42- and CO32- have little effect on the adsorption capacity of uranium by BT-NTO. However, the effect of F- is very significantly, but this effect can be greatly reduced by introducing Al3+. It should be noted that the BT-NTO can be regenerated with 0.1 mol／L HNO3 solution, and can be reused many times without obvious decreased of adsorption capacity.