Adsorption of Imidazolium-Based ILs Combined on Activated Carbon Obtained from Grape Seeds

In this work, the adsorption of imidazolium-based ionic liquids containing the bis(trifluoromethanesulfonyl) imide anion (NTf₂^-) from aqueous phase was evaluated using different activated carbons (ACs). Three commercial Acs and two Acs prepared from grape seeds (one produced by pyrolysis and the other by hydrothermal carbonization (HTC), both activated with potassium hydroxide) were tested, assessing the adsorption of both the cation and the anion. For commercial ACs, similar adsorption performances were observed, with maximum adsorption capacities ranging from 0.85 to 1.08 mmol g^-1. These values increased under acidic conditions (pH 4), reaching 1.74 mmol g^-1 for the 1-butyl-3-methylimidazolium cation (Bmim⁺) and 1.87 mmol g^-1 for NTf₂^-. Among the prepared ACs, the HTC-derived AC showed slightly higher capacities than the commercial samples, while the pyrolysis-derived AC exhibited the highest adsorption capacity for BmimNTf₂ (3.36 mmol g^-1 at pH 4). In terms of reusability, the pyrolysis-derived AC maintained 84% of its initial adsorption capacity between the third and fifth regeneration cycles. These results highlight the high adsorption performance and recyclability of grape-seed-derived activated carbons, demonstrating their potential for the removal of ionic liquids from aqueous environments.