Al掺杂KIT-6材料的合成及其亚甲基蓝吸附性能

Synthesis of Al-doped KIT-6 materials and their adsorption properties for methylene blue

KIT-6是典型的三维有序介孔氧化硅材料,在催化和吸附等领域具有广泛的用途。通过掺杂骨架Al赋予KIT-6材料酸性位,能显著提升Al-KIT-6材料的吸附性能;然而以无机硅源和铝源可控合成Al-KIT-6是难点。利用粉煤灰基硅酸钠溶液,通过pH值控制水热法诱导Al原子进入KIT-6材料的硅骨架,直接合成了一系列Al-KIT-6材料。通过N_(2)-物理吸附、XRD、TEM、Al核磁共振、XPS和NH_(3)-TPD表征了Al-KIT-6的织构性质;结果显示合成的Al-KIT-6保留了有序介孔结构;Al主要掺杂进入KIT-6材料骨架中,显著提升了KIT-6的酸量和强度。碱性亚甲基蓝分子的吸附实验表明,Al-KIT-6吸附材料的吸附容量随着Al掺入量的增加而变大。吸附动力学实验显示Al-KIT-6材料对亚甲基蓝的吸附过程符合拟二级动力学,吸附等温线模型拟合结果显示吸附过程符合Langmuir吸附模型。

KIT-6 is a typical three-dimensional ordered mesoporous silica,which has a wide range of applications in the fields of catalysis and adsorption.By doping the framework Al to endow the KIT-6 material with acid sites,the adsorption performance of the Al-KIT-6 material for basic dye molecules can be significantly improved.However,it is difficult to controllably synthesize Al-KIT-6 with inorganic silicon and aluminum sources.In this study,a series of Al-KIT-6 materials were directly synthesized by a pH-controlled hydrothermal method with fly ash-based sodium silicate,which can induce Al atoms doping into the KIT-6 silicon framework.The texture properties of Al-KIT-6 were characterized by N_(2)-physical adsorption,XRD,TEM,Al NMR,XPS and NH_(3)-TPD.The results showed that the synthesized Al-KIT-6 material had an ordered mesoporous structure.Al was mainly doped into the framework of KIT-6 material,thereby significantly increasing the acid content and acid strength.The adsorption experiments of the synthesized Al-KIT-6 materials on basic methylene blue molecules showed that the adsorption capacity of the Al-KIT-6 materials increased with the increase of Al incorporation.The adsorption kinetic experiments showed that the adsorption process conformed to the pseudo-second-order kinetics,and the adsorption isotherm model fitting results showed that the adsorption process conformed to the Langmuir adsorption model.