2-吡啶甲醛功能化SBA-15介孔材料的制备及其对Cr(Ⅲ)离子的吸附

Synthesis of 2-pyridinecarboxaldehyde functionalized SBA-15 mesoporous material for the adsorption of Cr(Ⅲ)ions from aqueous solution

通过席夫碱反应将2-吡啶甲醛成功嫁接到氨基化的SBA-15介孔分子筛上,本文获得了一种新型功能化SBA-15吸附剂(N-SBA-15)。采用傅里叶变换红外光谱、X射线衍射、元素分析、扫描电子显微镜、透射电子显微镜、X射线光电子能谱、热重分析和氮气吸附-脱附等手段对N-SBA-15的表面官能团、形貌、孔道结构和表面化学性质进行了详细的表征分析。利用N-SBA-15对水溶液中的Cr(Ⅲ)进行了吸附实验,其最大吸附容量为84.3mg/g。动力学分析和等温吸附研究结果表明,N-SBA-15对Cr(Ⅲ)的吸附过程符合准二级动力学模型和Langmuir模型。吸附热力学分析表明,该吸附过程是自发的吸热过程(ΔG<0、ΔS>0、ΔH>0)。吸附机理分析表明该吸附过程主要是由N-SBA-15表面有机官能团与Cr(Ⅲ)的配位作用实现的。而且,N-SBA-15吸附剂经过5次吸附-脱附测试,仍然对Cr(Ⅲ)具有较高的吸附容量。

A novel functionalized SBA-15 material(N-SBA-15)was synthesized via Schiff's base reaction of 2-pyridinecarboxaldehyde with amino modified SBA-15 mesoporous material for adsorption of Cr(Ⅲ)ions from aqueous solution.The organic functional groups,morphology,pore structure and chemical property of N-SBA-15 were determined by FTIR,XRD,EDX,SEM,TEM,XPS,TGA and N2 adsorption-desorption.Moreover,the adsorption performance of N-SBA-15 adsorbent on Cr(Ⅲ)ions in aqueous solution was investigated.The adsorption capacity of 84.3mg/g toward Cr(Ⅲ)ions was obtained.The kinetics analysis and adsorption isotherms revealed that the adsorption process of Cr(Ⅲ)ions by N-SBA-15 was consistent with pseudo-second-order kinetic model and Langmuir isotherm model.The thermodynamic parameters showed that Cr(Ⅲ)adsorption onto N-SBA-15 was spontaneous,endothermic and entropy-increasing process(?G<0,?S>0,?H>0).The adsorption mechanism analysis indicated that Cr(Ⅲ)adsorption onto N-SBA-15 was mainly based on the chemical combination of N atoms on the organic functional groups of N-SBA-15 through coordination bond.Furthermore,N-SBA-15 still kept high adsorption capacity after five adsorption–desorption cycles.