U(Ⅵ)在偕胺肟基功能化介孔二氧化硅上的吸附

通过嫁接法合成了偕胺肟基功能化修饰的介孔二氧化硅SBA-15-AO和SBA-15-2AO,采用傅里叶红外谱图(FTIR)、X射线粉末衍射(XRD)、透射电镜(TEM)、比表面分析(BET)和元素分析等手段对所合成的样品进行了表征;采用批式法对比研究了U(Ⅵ)在未功能化的SBA-15和偕胺肟功能基含量不同的样品SBA-15-AO和SBA-15-2AO上的吸附行为。结果表明:偕胺肟基的引入未破坏SBA-15的孔结构,其比表面积和孔体积有所减小,但对U(Ⅵ)的吸附能力显著增强;室温下,偕胺肟基团含量较大的SBA-15-2AO对U(Ⅵ)的吸附能力最大,其最大吸附容量约为0.885mmol/g,是未功能化的SBA-15最大吸附容量的4倍;U(Ⅵ)在SBA-15、SBA-15-AO和SBA-15-2AO上的吸附均较迅速,180 min达到吸附平衡,均符合准二级吸附动力学模型;吸附过程受pH影响显著,但离子强度对吸附的影响较小,吸附为放热过程;在一系列干扰离子存在下,偕胺肟基功能化的SBA-15对U(Ⅵ)具有良好的吸附选择性。

Sorption of U(Ⅵ) on Amidoxime-Functionalized Mesoporous Silica

Two amidoxime-functionalized mesoporous silica (SBA-15) materials were prepared by a post-grafting method, and characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), Brunner Emmet Teller (BET) measurements, and elemental analysis. The sorption of U(Ⅵ) on SBA-15 and amidoxime-functionalized SBA-15 was investigated by a batch method. The results indicate that the pore structure of amidoxime-functionalized mesoporous silica is the same as SBA-15, but the pore volume and BET surface area decreases. Compared to SBA-15, the sorption ability of amidoxime-functionalized SBA-15 for U(Ⅵ) is obviously increased. SBA-15-2AO with more amidoxime groups has the highest adsorption capacity of about 0.885 mmol/g for U(Ⅵ), which is 4 times of SBA-15. The sorption process is exothermic and follows a pseudo-second-order type sorption kinetics for all materials. In addition, U(Ⅵ) adsorption depends strongly on pH, but the effect of ionic strength is weak. Amidoxime-functionalized mesoporous silica exhibites high selectivity and a better sorption ability for U(Ⅵ) over a series of competing metal ions.