A multifaceted poly(ionic liquid)-based superabsorbent hydrogel for simultaneous removal of heavy metals and synthetic dyes

Abstract

Water pollution remains a critical global concern, significantly intensified by rapid industrial development, agricultural runoff, and untreated urban discharges. In response to this environmental challenge, we have developed a poly(ionic liquid)-based hydrogel as a multifunctional and sustainable platform for simultaneous removal of heavy metals and organic dyes (both cationic and anionic) from wastewater. The hydrogels are synthesized via a one-pot polymerization–gelation process employing 2-acrylamido-2-methyl-1-propanesulfonic acid and vinyl imidazole as monomers. Quaternization of the imidazole moiety with 1,10-dibromodecane facilitated both crosslinking and ionic network formation. The resulting hydrogel, with 10% crosslinking density, demonstrated remarkable swelling capacity (2570%), indicating its superabsorbent nature. In rheological analysis, a dominant elastic behaviour with a coherent solid nature was observed for all the hydrogels. The FE-SEM study revealed a layered, interconnected structure with porosity in the interconnected region, signifying promising absorption potential. The hydrogels are explored towards the removal of carcinogenic heavy metals (Pb, Hg, Cd, Cr), and organic dyes. Due to the presence of both cationic and anionic polymer chains, these PIL-based hydrogels are found to be very effective in the removal of both cationic and anionic dyes from water medium. The hydrogel showed an absorption capacity of 250 mg g⁻¹ and 490 mg g⁻¹ of heavy metals and dyes, respectively. The recyclability and reusability make these hydrogels a sustainable material for removing carcinogenic materials from water bodies.