Surface-Active Ionic-Liquid-Encapsulated Polyoxometalate Nanospheres: Construction, Self-Assembly, Adsorption Behavior, and Application for Dye Removal

The fabrication of materials that can efficiently adsorb environmental pollutants such as nonbiodegradable dyes is in urgent demand. In this work, the construction, characterization, and application of surface-active ionic-liquid-encapsulated polyoxometalates (SAILEPs) are reported. These hybrid materials with ordered structures are obtained in the aqueous phase by one-pot self-assembly at room temperature. They demonstrated a high capacity for the rapid adsorption of cationic dyes. The equilibrium time of rhodamine B (RhB) adsorption is only 1 min. These SAILEP materials also can selectively separate RhB from an eosin Y/RhB mixture. The fast and selective adsorption is attributed to electrostatic interactions and high affinities between SAILEPs and RhB. Meanwhile, investigation of the adsorption isotherms and kinetics indicates that the adsorption of dyes follows Langmuir isotherm models and pseudo-second-order kinetics. The self-assembly is investigated by small-angle X-ray scattering, Fourier transform infrared, and dynamic light scatttering. These studies offer further insight on the SAILEP hybrid materials, which have great potential in dye decontamination.