Effective and selective adsorption of organoarsenic acids from water over a Zr-based metal-organic framework

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 378; p. 122196
• Main Authors: Lin, Zu-Jin, Zheng, He-Qi, Zeng, Yong-Nian, Wang, Yu-Lin, Chen, Jin, Cao, Gao-Juan, Gu, Jia-Fang, Chen, Banglin
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-12-2019
• Subjects: Coordination interaction; Electrostatic interaction; Hydrogen bonding; Metal organic frameworks; p-Arsanilic acid; π-π Interaction; p-Arsanilic acid; π-π Interaction; Coordination interaction; Metal organic frameworks; Hydrogen bonding; Electrostatic interaction
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2019.122196

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•Seven Zr-based metal-organic frameworks were screened for OAAs capture from water.•The qm values over MOF-808F reached to 621.1 mg g−1 for ASA and 709.2 mg g−1 for ROX.•MOF-808F showed excellent selectivity and reusability, which were superior to MOF-808.•Electrostatic, H-bonding and π-π interactions were observed in ASA@MOF-808F.•While coordination interaction was the dominant force between ASA and MOF-808.
It is imperative to remove organicarsenic acids (OAAs) from water because they can convert into highly toxic inorganic arsenic compounds in natural environment via biotic and abiotic degradation routes. Herein, seven Zr-based metal-organic frameworks (Zr-MOFs) including DUT-67, UiO-66, UiO-67, MOF-808, MOF-808F, NU-1000, NU-1000B with various structures were screened for the adsorptive removal of representative OAAs including p-arsanilic acid (ASA) and roxarsone (ROX) in water media. Initial screening found that MOF-808 and MOF-808F have the largest adsorption capacities. Therefore, their adsorption behaviors including adsorption kinetics, isotherms, specificity and effects of pH were fully investigated. Remarkably, MOF-808F had the second largest maximum adsorption capacities of ASA (621.1 mg g−1) and ROX (709.2 mg g−1) among the reported MOF-based adsorbents. In addition, MOF-808F showed excellent selectivity and reusability and no observable drop of adsorption efficiency was found in the presence of equimolar competing ions (Cl−, OAc− or SO42−) or after three successive adsorptive runs. By contrast, MOF-808 had inferior adsorption specificity and reusability in spite of the very similar structure with MOF-808F. The structure-dependent adsorption performances can be explained by the distinct adsorptive mechanisms, which were revealed by zeta potential measurements, X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculation etc. The dominant interaction between MOF-808 and ASA was coordination interactions, while ASA adsorption over MOF-808F was governed by the synergistic effect of π-π stacking, hydrogen bonding, and electrostatic interactions. This work no only presented an excellent adsorbent (MOF-808F) toward OAAs, but also revealed the structure dependent adsorption performances/mechanisms.