Facile synthesis of DES-based functionalized Polyaniline@Fe3O4 magnetic microspheres for continuous and efficient dye removal: Properties and mechanism

Dyes are organic compounds that are necessary to impart color to substrates. Because methyl orange (MO) and methylene blue (MB) are difficult for the environment to biodegrade, it is critical that dyes be recycled quickly and efficiently. Herein, oxidation was used to create polyaniline@Fe3O4 nanorods (PANI@Fe3O4). Then, different types of deep eutectic solvents (DESs) were grafted to prepare several novel adsorption materials for green DESs-based magnetic nanomicrospheres (DESs-PANI@Fe3O4). The grafting of DESs not only increased the BET surface area (65.24 m2/g) of the adsorbent, provide a channel for rapid adsorption and efficient mass transfer of pollutants, but also provided abundant functionalized active sites (O-H, C = O, NH+) for efficient dye removal. Comparison of FTIR and XPS spectra before and after adsorption showed that specific functional groups (–OH, –NH2, –COOH) and functional chemical bonds (N-H, C-O, O-H) played an important role in rapid and effective dye removal. When grafted with ChCl-Lac as a green solvent, the adsorption capacity of the resulting ChCl-Lac-PANI@Fe3O4 for MO and MB dyes reached to 912.71 and 473.95 mg/g, respectively in a few minutes. Density functional theory (DFT) result showed that the adsorption was mainly promoted through π-π interaction, hydrogen bonding, and van der Waals interaction. In conclusion, DESs-PANI@Fe3O4 prepared by a facile strategy has the ability to remove dyes from wastewater continuously and efficiently, which provides a new concept for the industrial application of green DESs-based magnetic nanosphere adsorbent.