Synthesis, characterization, and application of β-cyclodextrin-based ion-imprinted polymer for selective sequestration of Cr(VI) ions from aqueous media: Kinetics and isotherm studies

Abstract

Toxic chromium(VI) is a menace to the environment and humans. Its tendency to transform into chromium(III) complicates its removal. An ion-imprinted polymer (IIP) synthesized by encapsulating 1,5′-diphenylcarbazide (DPC) ligand into the β-cyclodextrin cavities then held into position by 4-vinylpyridine and ethylene glycol dimethacrylate functional monomers (γ-MPS/β-CD/DPC/VP) were employed to investigate Cr(VI) removal efficacy. The corresponding non-imprinted polymer was also prepared, but the template ion was omitted. The inclusion of DPC ligand into the polymeric matrix was responsible for the pronounced selectivity observed due to the high affinity of DPC towards Cr(VI). Characteristic peaks at 3318, 1718, 1258 and 940 cm−1 apportioned to the –OH, CO, C–N, and Si–O–CH3 functional groups were observed in the FTIR spectra. The maximum Langmuir adsorption capacity obtained at 25 °C was 15.61 mg/g for IIP. The optimum solid/liquid ratio achieved at equilibrium time (240 min) was 10 g/L. The IIP selectivity order was Cr(VI)>Cr(III)>Co(II)>Zn(II)>Ni(II).