Ionic liquid-based amphiphilic conetwork with mechanical toughness: a promising candidate for dye removal

Hydrogels have been widely used in water treatment materials due to their intriguing three-dimensional cross-linked networks and a large number of functional groups. However, conventional chemically cross-linked hydrogels inevitably face severe problems such as insufficient adsorption performance and poor mechanical property. Here, a novel ionic liquid (IL)-based amphiphilic conetwork (APILCN) with homogeneous network and good adsorption capacity and mechanical strength was developed for the efficient treatment of anionic dye. The strategy was based on one-pot step polymerization of “A₃ + B₃” via N-alkylation reaction of a bromo-terminated A₃-type amphiphilic macromonomer and an imidazole-terminated B₃-type monomer. Under the optimum conditions, the maximum adsorption capacity of APILCN toward bromophenol blue (BPB) could reach ~ 397 mg g⁻¹ with a good mechanical strength of 2.44 MPa at the compressive strain of 60%. The excellent adsorption and mechanical property are attributed to the exposed IL functional groups and the homogeneous network structure, respectively. Furthermore, Freundlich and Langmuir model for the isothermal study of APILCN demonstrated that BPB adsorption mechanism varied with the different chemical structures of A₃ macromonomer, and the kinetic study revealed that the adsorption of BPB followed the pseudo-second-order kinetic model. In addition, APILCN was capable of selectively separating anionic dye and could remain 93.2% of the initial saturation adsorption capacity after five adsorption–desorption cycles. These results indicated that such APILCN was qualified for the work as efficient and stable adsorbents and, more importantly, the structure of APILCN might accelerate the application of the hydrogels in diverse fields.