Efficient dye removal and antibacterial activity of imidazole-crosslinked chitosan hydrogel for wastewater treatment

In this study, an imidazole cross-linked chitosan hydrogel (I/CS-4) was synthesized through the Debus-Radziszewski reaction, resulting in a multifunctional adsorbent with both dye adsorption and antimicrobial capabilities. I/CS-4 effectively removed orange G (OG) and metanil yellow (MY) dyes under various environmental conditions, including pH, initial concentration, temperature, and contact time. The hydrogel demonstrated high stability and efficiency over a broad pH range (2−10), attributed to its abundant amino and imidazole groups, which facilitate electrostatic, hydrogen bonding, and π-π stacking interactions. The maximum adsorption capacities for OG and MY were 565.00 mg/g and 490.20 mg/g, respectively, following the Langmuir isotherm and pseudo-second-order kinetic models. Additionally, I/CS-4 showed excellent recyclability, maintaining over 80 % removal efficiency after five cycles. It also exhibited potent antibacterial activity against E. coli and S. aureus while being biocompatible. These results highlight I/CS-4's potential as an effective material for treating dye-containing wastewater, combining efficient contaminant removal with microbial inhibition.