HKUST-1晶格空位的构建及对偶氮染料吸附的影响

Construction of lattice vacancy in HKUST-1 and effect on adsorption of azo dyes

采用1,3-苯二甲酸与1,3,5-苯三甲酸不同摩尔比例的混合配体策略,制备了4类具有晶格空位的Cu基金属有机框架化合物HKUST-1,并研究了其对刚果红和亚甲基蓝的吸附性能。利用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、BET比表面积测定仪、热重分析仪(TGA)进行表征,证实了HKUST-1晶格空位的框架结构与稳定性,晶格空位HKUST-1的BET表面积和总孔容(1 220 m^2·g^(-1)和0.62 cm3·g^(-1))均大于初始HKUST-1(698 m^2·g^(-1)和0.40 cm^3·g^(-1))。吸附实验表明,由于尺寸排阻效应,晶格空位HKUST-1的构建增加了与刚果红的结合能力,且与亚甲基蓝相比,晶格空位HKUST-1对刚果红具有更高的吸附选择性。随着有机配体1,3-苯二甲酸与1,3,5-苯三甲酸的摩尔比例(0:1,1:1,2:1,3:1)的增加,晶格空位HKUST-1对刚果红的吸附去除效果随之增加,室温、pH 6.0条件下,Langmuir吸附量增加了1.53倍,Langmuir最大吸附量为528.03 mg·g^(-1),吸附过程符合准二级动力学和Langmuir吸附等温线模型。

Using 1,3-benzenedicarboxylic acid as the modulator, through changing the ratio of different ligands in the reactants, employing mixed ligand strategy method, the crystals of copper-based metal organic frameworks HKUST-1 with different ratio of lattice vacancy were prepared with comparatively large adsorption capacity of azo dye molecules. With the aid of SEM, XRD pattern, TGA analysis and N2 adsorption-desorption experiment,the skeleton structure and the thermal stability of HKUST-1 were confirmed. The resulting shows HKUST-1 with lattice vacancy has high BET surface area and total pore volume（1 220 m^2·g^（-1）,0.62 cm^3·g^（-1））, which are both larger than those of the parent compound（698 m^2·g^（-1）, 0.40 cm^3·g^（-1））. The adsorption experiment revealed that the lattice vacancy in HKUST-1 significantly improved the combining ability of HKUST-1 with congo red as the ratio（0：1, 1：1, 2：1, 3：1） of 1,3-benzenedicarboxylic acid to 1,3,5-benzene three formic acid increased, while the defective HKUST-1 showed high selectivity for congo red over methylene blue due to the size exclusion effect caused by the structure of the skeleton defect, Langmuir adsorption can be increased by 1.53 times at room temperature,and the Langmuir adsorption capacity of congo red was 528.03 mg·g^（-1） at 25？C. The kinetics of adsorption exhibited pseudo-second-order behavior. The adsorption performance were well described by the Langmuir isotherm model.This study provides design of HKUST-1 potential strategies for the separation of dye molecules.