Gadolinium metal-organic frameworks realizing ultra-high adsorption capacity toward anionic dyes in aqueous solution.

With the development of various industries, the impact of organic dye wastewater discharge on the environment cannot be ignored. Adsorbents and their adsorption properties are the key to the removal of organic dyes from wastewater. In this study, gadolinium metal organic frameworks (Gd-BDC, Gd-BDC-NH 2) were synthesized for the adsorption of anionic dyes in water and exhibited excellent adsorption performance, particularly in Congo red (CR) up to 4592.3 and 5507.1 ​mg ​g−1 at room temperature, respectively. The kinetics simulation showed that the adsorption process was more consistent with the pseudo-second-order model; while the Freundlich model is more suitable to describe the isothermal adsorption process of Gd-MOFs. The electrostatic interaction, π-π stacking and hydrogen bonding between the anionic dye CR and the cationic material Gd-MOFs are the main reasons for the ultra-high adsorption of CR. The excellent adsorption performance on anionic dyes indicates that it is a promising high-performance adsorbent. Gadolinium Metal-organic frameworks (Gd-BDC, Gd-BDC-NH 2) with high adsorption capacity for anionic dyes in water were synthesized in this study. In particularly, the adsorption capacity for Congo red (CR) at room temperature was 4592.3 and 5507.1 ​mg ​g−1, respectively. The excellent adsorption performance indicates that they are promising high-performance adsorbents for CR. [Display omitted] • Gd-BDC and Gd-BDC-NH 2 adsorbents were sucessfully synthesized and showed significant adsorption capacity for anionic dyes, especially Congo red, reaching 4592.3 and 5507.1 ​mg ​g−1 at room temperature, respectively. • Gd-MOFs had a high effect on Congo red removal in a wide pH range (4–10). • Based on FTIR, XPS analyses and references, the reasonable adsorption mechanism of Congo red by Gd-MOFs was deduced. [ABSTRACT FROM AUTHOR]