Preparation of Benzimidazole-Modified Resin and Its Adsorption Behavior Toward Cu(II) and Ni(II) Ions in Aqueous Media

To address heavy metal contamination in wastewater, this study developed a novel chelating resin (PS-2-AB) by grafting 2-aminobenzimidazole onto chloromethylated polystyrene. The resin was characterized using SEM, BET, FTIR, and XPS to confirm successful modification and analyze its structural properties. Batch adsorption tests were conducted to evaluate its removal performance for Cu(II) and Ni(II) ions. Under optimal conditions (pH 5.0–7.0, dosage: 1.0 g/L), PS-2-AB achieved maximum adsorption capacities of 125.04 mg/g for Cu(II) and 157.44 mg/g for Ni(II), which are significantly higher than those of the commercial resin D113 (44.68 mg/g for Cu(II) and 25.17 mg/g for Ni(II)) under the same conditions. Adsorption kinetics followed the pseudo-second-order model, indicating chemisorption-dominated behavior, while equilibrium data fit the Langmuir model, suggesting monolayer adsorption. Thermodynamic parameters confirmed a spontaneous and endothermic process. After five regeneration cycles, PS-2-AB retained approximately 87% (Cu) and 89% (Ni) of its original capacity, demonstrating good reusability. These results indicate that PS-2-AB exhibits markedly better adsorption performance than D113, making it a promising and cost-effective adsorbent for the efficient removal of Cu(II) and Ni(II) from aqueous media.