The contamination of wastewater by heavy metals, particularly hexavalent chromium (Cr⁶⁺), poses a serious environmental and health risk due to its high toxicity and persistence. Although conventional treatments such as chemical precipitation, advanced filtration, and coagulation-flocculation exist, they tend to be costly, non-selective, or generate secondary waste. This research presents the synthesis of interpenetrating hydrogels based on chitosan (QS) and poly(vinylimidazole) (PVI). PVI was obtained by bulk polymerization using AIBN as a free radical generator. Three formulations were proposed for obtaining PVI polymers, varying the percentage of PVI. The proportions established were 50:50, 70:30, and 80:20. PVI polymers were characterized by FTIR, TGA, and SEM. In the FTIR spectrum, a band was observed in the region of 3200–3500 cm−1 due to N–H and O–H stretching vibrations. The bands at 2873, 1640, 1570, and 1370 cm−1 correspond to the stretching vibration of C–H, stretching of -C–O, bending of the N–H group, and bending of C–H of chitosan. The adsorption results were evaluated by varying the pH and initial Cr⁶⁺ concentration. The Langmuir adsorption isotherm showed an adsorption qmax of 150 mg/g at pH 2. The kinetic data were best fitted to the pseudo-second-order kinetic model. PVI polymer offers an alternative for the treatment of heavy metal-contaminated water.

We would like to thank the Secretaría de Ciencia, Humanidades, Tecnología e Innovación for the Master's scholarship awarded. I would also like to extend our special thanks to Dr. Jesús Ortiz Palacios for his valuable guidance and contributions to the development of this research.