Synthesis, structural characteristics, and adsorption properties of benzimidazole-functionalized hyper-cross-linked resin

Abstract

Macroporous chloromethylated polystyrene (CMPs) has found extensive applications in wastewater treatment owing to its distinct chemical structure and adsorption performance. To enhance its adsorption capability, a series of meticulously designed chemical reactions were implemented in this work. Particularly, specific functional groups were ingeniously introduced via a Friedel–Crafts alkylation reaction combined with a nucleophilic substitution reaction. The result was the successful synthesis of benzimidazole-modified CMPs (BZI-HCMPs). This newly modified adsorbent exhibited exceptional adsorption performance in the presence of salicylic acid (SA) in an aqueous solution. The maximum adsorption capacity of BZI-HCMPs was 295.1 mg g⁻¹ at 313 K, with the Freundlich model providing a better fit for equilibrium data. The adsorption process was rapid, reaching equilibrium within just 70 minutes. Compared with the pseudo-second-order model, the pseudo-first-order model precisely described the kinetic data of this adsorption process, providing robust theoretical support for a deeper understanding of the adsorption mechanism. Furthermore, BZI-HCMPs are reusable and maintain high adsorption capacity after several adsorption–desorption cycles. This work affords a new method for the adsorption of SA from aqueous solutions.