Collaborative Innovation Center for Advanced Nuclear Energy Technology, INET, Tsinghua University, Beijing, 100084, PR China; Beijing Key Laboratory of Radioactive Waste Treatment, INET, Tsinghua University, Beijing, 100084, PR China.
College of Chemistry and Materials Science, Sichuan Normal University, Chengdu, 610066, PR China.
Environ Pollut. 2019 Oct;253:616-624. doi: 10.1016/j.envpol.2019.07.069. Epub 2019 Jul 15.
The development of high-efficiency adsorbents and the exploration of their adsorption mechanisms are major challenges in environmental remediation. Herein, MIL-100 was prepared, characterized, and utilized for the adsorptive removal of diclofenac sodium (DCF) from aqueous solutions. A high monolayer adsorption capacity of 773 mg g was recorded. The adsorption mechanism was proposed based on different contributions of two types of pore structure of MIL-100 to the adsorption of DCF from aqueous solutions according to the experimental results and theoretical calculation. During adsorption process, DCF (5.2 × 7.4 × 10.3 Å) diffused through the free area of hexagonal pores (8.6 × 8.6 Å) into the cages of MIL-100, whilst it was adsorbed by the pentagonal pores (4.8 × 5.8 Å) preferentially. Internal mass transfer resistance, which was identified as one of the dominant rate-limiting steps by the mass transfer resistance kinetic models based on the Sips model, will be derived from the diffusion process, which was affected by the size-sieving effect of the pore structure of MIL-100. The successful diffusion of DCF into the interior of MIL-100 and the stable configuration between MIL-100 and DCF accounted for the high adsorption capacity. The capture of DCF into MIL-100 also resulted in the pore size distribution variation of adsorbent, which provided vital experimental evidence for the proposed mechanism. This study may offer deeper insights into other pollutants removal by metal-organic frameworks type adsorbents.
高效吸附剂的开发和吸附机制的探索是环境修复的主要挑战。在此，制备、表征并利用 MIL-100 从水溶液中吸附去除二氯芬酸钠 (DCF)。记录到 773mg/g 的高单层吸附容量。根据实验结果和理论计算，提出了吸附机制，认为 MIL-100 两种类型的孔结构对 DCF 从水溶液中的吸附有不同的贡献。在吸附过程中，DCF（5.2×7.4×10.3Å）通过六方孔（8.6×8.6Å）的自由面积扩散进入 MIL-100 的笼中，而优先被五角孔（4.8×5.8Å）吸附。通过基于 Sips 模型的传质阻力动力学模型确定的内部传质阻力被鉴定为主要限速步骤之一，这是由 MIL-100 的孔结构的筛分效应影响的扩散过程引起的。DCF 成功扩散到 MIL-100 的内部以及 MIL-100 和 DCF 之间的稳定构型解释了高吸附容量。DCF 被捕获到 MIL-100 中也导致了吸附剂的孔径分布变化，这为所提出的机制提供了重要的实验证据。本研究可能为金属-有机骨架型吸附剂去除其他污染物提供更深入的见解。
