短孔道介孔二氧化硅SBA-15对铀的吸附性能

Adsorption of uranium(Ⅵ)on silica mesoporous material SBA-15 with short channels

以短孔道介孔二氧化硅SBA-15为铀吸附剂,考察吸附时间、初始液pH、初始浓度对吸附性能的影响,并分析了吸附动力学和吸附等温线以及吸附前后红外光谱变化。结果表明,初始液pH对吸附具有重要的影响,最佳吸附的pH值为6;吸附在30min即可达到平衡;当初始浓度为100mg·L-1时,饱和吸附量为311mg·g-1;吸附量随铀溶液初始浓度的增大而增大,而吸附百分数则相反;吸附等温线符合Langmuir和Freundlich吸附模型,吸附动力学符合准二级动力学方程;吸附过程中起主要作用的基团是Si—OH和Si—O—Si。

SBA-15 with short channels was employed as adsorbent for uranium ions.Different factors including contact time,initial pH value and initial concentration of solution were examined to investigate their effects on adsorption of uranium by SBA-15 with short channels.Adsorption kinetics,adsorption isotherms and changes of FT-IR spectra of SBA-15 with short channels before and after adsorption were also studied.According to the experiment,uranium adsorption on SBA-15 is strongly pH-dependent and the maximum adsorption occurs at pH of 6,the adsorption reaches equilibrium within 30 min and the maximum adsorption capacity is 311 mg·g-1 for initial solution concentration of 100 mg·L-1.Adsorption capacity increases but adsorption percentage decreases with the increase of initial uranium concentration.Adsorption isotherm follows both Langmuir and Freundlich models,and pseudo-second order rate equation is better to describe kinetic process.The Si—OH and Si—O—Si groups existing in SBA-15 are mainly responsible for the adsorption of uranium.