Diamino-functionalized metal-organic framework for selective capture of gold ions

• Published in: Chemosphere (Oxford) Vol. 362; p. 142686
• Main Authors: Wu, Mengdi, Tian, Heli, Gao, Xinli, Cui, Xinge, Li, Zhengjie, Li, Kunjie, Zhao, Xudong
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.08.2024
• Subjects: Diamino groups; Gold ion; Metal-organic framework; Selective adsorption; Metal-organic framework; Gold ion; Diamino groups; Selective adsorption
• ISSN: 0045-6535; 1879-1298; 1879-1298
• DOI: 10.1016/j.chemosphere.2024.142686

Adsorptive recovery of valuable gold (Au) ions from wastes is vital but still challenged, especially regarding adsorption capacity and selectivity. A novel M − 3,5-DABA metal-organic framework (MOF) adsorbent was prepared via anchoring 3,5-diaminobenzoic acid (3,5-DABA) molecule in the MOF-808 matrix. Benefiting from the positive charge property, dense amino groups (3.2 mmol g−1) and high porosity, the adsorption capacity of M − 3,5-DABA reaches 1391.5 mg g−1 (pH = 2.5) and adsorption equilibrium is attained in 5 min. This amino-based material shows excellent selectivity towards various metal ions, evading the poor selectivity problem of classical thiol groups (e.g. for Ag+, Cu2+, Pb2+ and Hg2+ ions). In addition, the regeneration was easily achieved via using a hydrochloric acid-thiourea eluent. Experimental analysis and density functional theory (DFT) calculation show the amino group works as a reductant for Au(III) ions and meanwhile acts as an active site for adsorbing Au(III) ions together with the μ-OH group. Thus, M − 3,5-DABA can act as a potential adsorbent for Au(III) ions, and our work offers a viable strategy to construct novel MOF-based adsorbents. [Display omitted] •An acid-exchange method was applied to construct the novel adsorbent M − 3,5-DABA.•M − 3,5-DABA shows a large adsorption capacity and rapid kinetics for Au(III) ion.•M − 3,5-DABA can selectively capture Au(III) ion than other co-existing ions.•Au(III) ions are simultaneously adsorbed and reduced by M − 3,5-DABA.