单宁为模板水热合成纳米TiO2及其对铀的吸附

Hydrothermal Synthesis of Nano-TiO2 Using Tannins as Templates and Its Adsorption Performance for Uranium

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FTIR、XRD、BET、SEM、TEM对合成的T-NTO的结构及形貌进行表征,并考察其对铀的吸附性能。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;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318 K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+、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。

Nano-titanium dioxide(T-NTO)was prepared by hydrothermal synthesis using different tannins as templates.The structure and morphology of the samples were characterized by FTIR,XRD,BET,SEM and TEM.Its adsorption performances for uranium were investigated.The results showed hydrothermal synthesis using tannin as template obviously improved the specific surface area and adsorption capacity of T-NTO.It was found that T-NTO had a strong adsorption capacity for uranium,and the adsorption capacity of the T-NTO samples prepared using different tannins as templates for uranium(UO22+)was significantly different.The nano-titanium dioxide(BT-NTO)prepared using bayberry tannin as template had the smallest particle size and its specific surface area was up to 96.61 m2/g.Further more,the adsorption process of uranium by T-NTO was described by Langmuir isothermal model,and the adsorption capacity of BT-NTO to uranium reached 0.7054 mmol/g at 318 K.The adsorption kinetics followed the pseudo-second-order kinetic equation.In addition,coexisting ions,including Zn2+,Mg2+,Pb2+,Mn2+,Na+,Cl–,SO42–and CO32–had little effect on the adsorption capacity of uranium by BT-NTO,while F–had greater effect.However,the influence of F–could be reduced by introducing Al3+.The BT-NTO could be regenerated with 0.1 mol/L HNO3 solution,and it could be reused many times without obvious decrease of adsorption capacity.