Synthesis of poly(ionic liquid)s with high specific surface areas for m-cresol adsorption

Developing ideal adsorbents for moving phenolic compounds from aqueous solutions remains a challenge. Herein, novel poly(ionic liquid)s (PILs) of PIL-Ba-x and PIL-An-5 were prepared via Friedel–Crafts alkylation using benzyl alcohol and aniline auxiliary cross-linking agents, respectively, for the adsorption of m-cresol in the aqueous phase. The specific surface areas and pore volumes of the synthesized PILs can be adjusted by pre-polymerization time, thereby realizing the regulation of the adsorption property of m-cresol. Results showed that the adsorption kinetics of PILs conformed to pseudo-second-order kinetics and reached adsorption equilibrium within 6 min. Their adsorption thermodynamics conformed to the Langmuir models. Based on the fitting data of the Langmuir model, the maximum adsorption capacity of m-cresol by PIL-Ba-5 can reach 228 mg/g. Moreover, the mechanism analysis showed that hydrogen bonding, electrostatic interaction, and π–π interaction promoted the adsorption of m-cresol by PIL-Ba. After the adsorption of m-cresol was separated by anhydrous ethanol, the adsorbent was recovered at least five times, and the removal efficiency was stable.