Adsorption behavior of hexavalent chromium in aqueous solution by polyvinylimidazole modified cellulose

Developing multifunctional adsorbent materials is an effective solution to hexavalent chromium (Cr (VI)) pollution. In this study, 3D macroporous materials with the synergetic advantages of cellulose and polyvinylimidazole were fabricated through a homogeneous method, and served as effective adsorbents for Cr (VI) elimination in aqueous solution. The physicochemical properties of the designed materials were studied by SEM, FTIR, 13C NMR, XPS, and CHN element analysis, and the results confirmed that imidazole groups were successfully grafted onto the macroporous cellulose. The influences of different water chemistry conditions, including contact time, temperature, initial solution pH value, and coexisting ion concentration, on the adsorption performance of the modified cellulose adsorbents were studied, and the corresponding adsorption mechanism was explored. The optimized adsorbent showed a fast adsorption rate (0.12 g/(mg∙min)), and a high adsorption ability (134 mg/g). The adsorption process was spontaneous and conformed to Langmuir isotherm and pseudo-second kinetic models. The Cr (VI) uptake mechanism of the designed materials was primarily controlled by electrostatic attraction, ion exchange, and redox. These results suggest that cellulose modified with imidazole groups is a promising candidate for the adsorption and detoxification of Cr (VI).