金属有机骨架MIL-101(Fe)吸附As(Ⅲ)的性能

Adsorption performance of As (Ⅲ) by metal-organic frameworks of MIL-101 (Fe)

以对苯二甲酸为有机配体,Fe(Ⅲ)为中心金属,采用溶剂热法合成了金属有机骨架材料MIL-101(Fe),通过XRD,SEM对其结构进行了表征.用MIL-101(Fe)吸附溶液中的As(Ⅲ),考察了溶液pH值、反应时间、溶液浓度及温度对吸附的影响.结果表明:溶液pH对吸附影响明显,pH=9时,吸附效果最佳;MIL-101(Fe)对As(Ⅲ)的吸附速率较快,吸附过程符合拟二级动力学;等温吸附实验数据用Langmuir和TemKin模型拟合良好,303 K条件下,MIL-101(Fe)对As(Ⅲ)的最大吸附量为211.42 mg·g^(-1);热力学参数ΔG、ΔH均小于0,吸附过程为自发放热反应;MIL-101(Fe)的中心金属Fe与亚砷酸根的配位作用在吸附过程中起主要作用.

In this study,metal-organic framework MIL-101 was prepared by hydrothermal method using terephthalic acid as the organic ligand and Fe(Ⅲ) as the central metal ion. The obtained MIL-101(Fe) was characterized by XRD,SEM and employed for the adsorption of As(Ⅲ). The effects of pH value,reaction time,solution concentration and temperature on the adsorption of As(Ⅲ) were investigated. The results showed that the effect of solution pH on adsorption was significant and the best adsorptive effect could be achieved at pH=9.The adsorption of As(Ⅲ) by MIL-101(Fe) was rapid and the process followed pseudo-second order kinetics. The experimental data of isothermal adsorption were fitted with the Langmuir and TemKin models,and the maximum adsorption capacity was 211.42 mg·g-1 at 303 K. Since its ΔG and ΔH were both less than zero,the adsorption process was a spontaneous exothermic reaction. The coordination interaction between the central metal Fe and arsenous anion in MIL-101(Fe) played a major role in the adsorption process.