不同配体结构的镧基MOF高效吸附刚果红染料

Lanthanide-based MOFs with Different Ligand Structures Efficiently Adsorbed Congo Red Dye

文章采用六水合硝酸镧作为金属离子源,分别与对苯二甲酸(BDC)、均苯三甲酸(BTC)、均苯四甲酸(PMA)以及4,4'-联苯二甲酸(BDA)4种不同的有机配体结合,通过溶剂热法成功制备了一系列镧基金属有机框架(La-MOF)。通过扫描电子显微镜(SEM)、X射线衍射(XRD)、X射线光电子能谱(XPS)以及比表面积与孔隙度分析(BET)等表征手段,研究了不同有机配体所合成La-MOF的物理化学性质。此外,通过批量实验探讨了pH、温度、接触时间以及多次循环对吸附刚果红(CR)性能的影响,并推导了相应的反应机理。结果表明,4种La-MOF的吸附过程均符合准二级动力学模型和Langmuir等温线模型。通过等温线模型拟合,得到4种材料的饱和吸附容量分别为La-BDC(2249.56 mg/g)>La-PMA(1864.40 mg/g)>La-BTC(1632.87 mg/g)>La-BDA(1037.52 mg/g)。综合分析显示,La-BDC具有更佳的综合吸附性能,其吸附机理主要涉及氢键、π-π键作用以及静电相互作用,但其在循环利用性方面表现出一定的不足。

A series of lanthanum-based metal organic frameworks(La-MOFs)were successfully prepared by solvothermal method by combining with four different organic ligands,namely terephthalic acid(BDC),terephthalic acid(BTC),homoph⁃thalic acid(PMA)and 4,4'-biphenyldicarboxylic acid(BDA),using lanthanum nitrate hexahydrate as a metal ionsource.The physicochemical properties of La-MOF synthesized by different organic ligands were studied in detail by scanning electron microscopy(SEM),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),and specific surface area and porosity analysis(BET).In addition,the effects of pH,temperature,contact time and multiple cycles on the adsorption of Congo Red(CR)were investigated through batch experiments,and the corresponding reaction mechanism was derived.The results show that the adsorption processes of the four La-MOFs conform to the quasi-second-order kinetic model and the Langmuir isotherm model.By isotherm model fitting,the saturated adsorption capacities of the four materials were La-BDC(2249.56 mg/g)>La-PMA(1864.40 mg/g)>La-BTC(1632.87 mg/g)>La-BDA(1037.52 mg/g).The comprehensive analysis showed that La-BDC had better comprehensive adsorption performance,and its adsorption mechanism mainly involved hydrogen bonding,π-πbonding and electrostatic interaction.However,La-BDC shows certain shortcomings in terms of recyclability.