How Ionic Liquid Gels Work on the Removal of Bisphenol A from Wastewater

The occurrence of emerging pollutants in water bodies is a pressing issue of modern society and identifying materials to remove them is the main target of current research. In this work, we prepared and characterized supramolecular gels of 1,3:2,4-dibenzylidene-d-sorbitol (DBS) in ionic liquids differing for the anion and the aliphatic or aromatic nature of the cation. We characterized our gels for their thermal stability and mechanical properties. We also found that all gels self-heal in 24 h after being cut by a razor blade. We then used our gels as sorbents to remove bisphenol A, an endocrine disruptor compound, from aqueous solutions. All gels adsorb BPA with high removal efficiencies, and those obtained in aliphatic ionic liquids act faster than their aromatic counterparts. The highest observed adsorption capacity was 314 mg/g. Gels were reused without loss in performance and need for intermediate washing, and the gel obtained in [bmpip][NTf₂] could be reused 37 times, maintaining a removal efficiency higher than 96%. It was loaded in a sequential system of syringes to treat flowing aqueous phases, removing 60% of BPA in 30 min. We also embedded the gel in the dialysis membrane and observed a removal efficiency of 85% after 48 h.