Selective Dye Adsorption by Zeolitic Imidazolate Framework-8 Loaded UiO-66-NH₂

• Main Authors: Hao Zhang, Xiaobo Shi, Jialiang Li, Parveen Kumar, Bo Liu
• Format: Article
• Language: English
• Published: MDPI AG 2019-09-01
• Series: Nanomaterials
• Subjects: ZIF-8; UiO-66-NH₂ composites; metal-organic frameworks; selective adsorption
• Online Access: https://www.mdpi.com/2079-4991/9/9/1283

In this study, Zeolitic Imidazolate Framework-8 (ZIF-8)-loaded UiO-66-NH₂ was synthesized, characterized, and analyzed for its potential to efficiently remove dyes. The selective adsorption on ZIF-8-loaded UiO-66-NH₂ or its parent MOFs (UiO-66-NH₂ and ZIF-8) in the mixed dyes solution was explored, including anionic dye (methyl orange (MO)) and cationic dyes (methylene blue (MB) and rhodamine B (RhB)). ZIF-8-loaded UiO-66-NH₂ displayed much better selectivity to MB than its parent MOFs. Adsorption capacity of ZIF-8-loaded UiO-66-NH₂ (173 mg/g) toward MB was found to be 215% higher than UiO-66-NH₂ (55 mg/g). A kinetics study based on adsorption data demonstrated that the adsorption process most closely matched with the model of pseudo-second-order kinetic and Langmuir isotherm. The adsorption was an exothermic and spontaneous physical process as revealed by the values of thermodynamic parameters. Furthermore, reusability of ZIF-8-loaded UiO-66-NH₂ was investigated and revealed the significant regeneration efficiency in adsorption capacity for MB even after four adsorption cycles. Experimental results proved that the interaction between ZIF-8-loaded UiO-66-NH₂ and MB was mainly affected by the mechanism, for instance, electrostatic interaction as well as π−π stacking interactions.