Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4989552 | Separation and Purification Technology | 2017 | 27 Pages |
Abstract
Seven water-stable metal-organic frameworks (MOFs) were prepared and tested for boron removal for the first time. XRD, SEM, nitrogen adsorption/desorption isotherms and thermogravimetric analysis were employed to confirm the structures. All the seven MOFs exhibit good boron adsorption capacities, especially ZIF-8 with an extraordinarily high capacity of 247.44 mg·gâ1 at 45 °C. The adsorption kinetics, isotherms, thermodynamics, mechanism and recycling of ZIF-8 were further investigated in batch adsorption process. Boron adsorption on ZIF-8 is a spontaneous endothermic process controlled by entropy change, reaches equilibrium in 1 h. Kinetic fitting of data indicates chemisorption is significant in the process and intraparticle diffusion is not the only rate-limiting step. Freundlich model describes the isotherms well, also suggesting chemisorption plays an important role in boron adsorption by ZIF-8. Characterization on exhausted ZIF-8 with 11B MAS NMR and XPS reveals that the three interactions happen mainly between boron and ZIF-8 at the Zn sites. The adsorption capacity does not decrease obviously after four cycles. ZIF-8 exhibits excellent boron adsorption capacity than all the previous materials, which makes it a promising agent for boron removal.
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Filtration and Separation
Authors
Jiafei Lyu, Nan Zhang, Hongxu Liu, Zhouliangzi Zeng, Jingshuang Zhang, Peng Bai, Xianghai Guo,