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-NH2) 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.