纯化及羧化多壁碳纳米管吸附铀的研究

Application of Purified and Carboxylic Multi-Walled Carbon Nanotubes for Uranium(Ⅵ) Ions Adsorptive Removal From Aqueous Solution

对商品多壁碳纳米管(MWNTs)进行纯化及硝酸羧化处理,并对其分别进行热重及红外表征。研究了纯化和羧化MWNTs对溶液中铀的吸附行为,考察了介质酸度、温度、吸附时间、溶液中铀的初始质量浓度对吸附容量的影响。实验结果表明,有质量比约为10%的羧基成功接枝于MWNTs,羧化MWNTs比纯化MWNTs表面更为粗糙,且出现羧基的特征红外波数为2 913cm-1及1 641cm-1。在pH=3.0～6.0范围内,2种MWNTs对铀的吸附量随着pH和平衡浓度的增大而升高,反应时间与温度对吸附容量的影响不大。2种MWNTs的等温吸附及热力学模型研究表明,吸附反应符合Freundlich和Langmuir方程,在最佳条件下,静态平衡吸附量分别为47.81mg/g和89.09mg/g。

Commercial multi-walled carbon nanotubes（MWNTs） were of purified and carboxylated, and characterized by thermogravimetric analysis（TGA） and infrared spectroscopy（IR）. The two nanomaterials were applied for the adsorption of uranium ion. The effects of acidity, temperature, time, and uranium initial mass concentration of the solution on the adsorption capacity were studied. The results show the grafted carboxyl group account for 10% of the carboxylated MWNTs mass, and the specific surface of carboxylic MWNTs is higher than the purified MWNTs, and the characteristic absorption peak V_asyn （1 641 cm^-1） of the carboxyl group is observed in the latter IR spectrum. In the pH value range of 3.0-6.0, the adsorption capacity of uranium on the two materials increases with the increase of the pH and equilibrium concentration, and is little influenced by reaction time and temperature. The adsorption isotherm and thermodynamic model of two materials were investigated. The results show that the adsorption can be described by with Freundlich and Langmuir equation, and the largest theoretic adsorption capacity are 47.81 mg/g and 89.09 mg/g, respectively.