Cationic Metal–Organic Framework with Amino-Functionalized Isonicotinic Acid for Chromium(VI) Removal
Shujing Hou, Fusheng Liu, Haomiao Xie, Fanrui Sha, Kira M. Fahy, Xiaoliang Wang, Chenghui Zhang, Yongwei Chen, Zhibo Li, Omar K. Farha
Abstract
The removal of hexavalent chromium, Cr(VI), from wastewater remains a significant environmental challenge. In this study, we explored the effectiveness of a novel cationic metal–organic framework (MOF), designated as NU-56, for Cr(VI) removal from wastewater. NU-56, composed of a Zr 6 O 8 cluster, monomeric Ni 2+, and 3-aminoisonicotinic acid, exhibits a remarkable Cr(VI) removal capacity. Several factors contribute to its efficacy, including the presence of free exchangeable Cl – ions within the network, protonated amino groups on the ligand, and μ 3 -O/OH on the Zr 6 O 8 cluster, all of which synergistically enhance NU-56’s ability to capture Cr(VI) efficiently under acidic aqueous conditions ranging from pH 4 to 6. In comparison to its isostructural counterpart lacking amino-functionalized isonicotinic acid, amino-functionalized NU-56 demonstrates superior structural integrity during the Cr(VI) elimination process. Additionally, we conducted comprehensive studies on the adsorption kinetics, isotherms, and selectivity of NU-56 for Cr(VI) removal, revealing its potential as a promising candidate with a maximum adsorption capacity of 68 mg/g. This research underscores the significance of developing functionalized MOFs as a viable approach for the removal of oxy-anions from wastewater, offering a straightforward and effective solution to address this pressing environmental concern.