Efficient and Selective Removal of Copper(II) from Aqueous Solution by a Highly Stable Hydrogen-Bonded Metal–Organic Framework

Copper(II) is an indispensable element in nature, while exposure to excessive Cu 2+ will potentially cause health issues. It is imperative to develop new strategies for efficient Cu 2+ uptake from aqueous solution. Herein, a hydrogen-bonded metal–organic framework (MOF) [(Zn 3 L 3 (H 2 O) 6 ][(Na)(NO 3 )] ( 1 ) with high stability was elaborately constructed. The uncoordinated carboxylate oxygen atoms in the channels of MOF were designed as active sites to recognize Cu 2+ and further coordinate with it. Without pretreatment, MOF 1 demonstrated a relatively high adsorption capacity (379.13 mg g –1 ), exceeding most Cu 2+ adsorbents. Even with the existence of different metal ions and a high concentration of interfering ions, highly selective adsorption of Cu 2+ can be achieved. Moreover, the excellent water stability together with the high removal efficiency in the presence of coexisting ions offers MOF 1 the possibility in practical application. The mechanism for Cu 2+ selective adsorption was systematically investigated by UV–vis, Fourier transform infrared, and fluorescence lifetime techniques, which may originate from the strong interaction between Cu 2+ and the carboxylate oxygen atoms. Our work may open an avenue to develop MOFs into adsorbent materials for water pollutants.