Adsorption behaviour of Eriochrome Black T from water onto a cross-linked β-cyclodextrin polymer

In this paper, a new β-cyclodextrin polymer (β-CDBEP) was successfully prepared by derivatizing with 1H-benzotriazole followed by cross-linking with epichlorohydrin. The adsorption behaviour of β-CDBEP for anionic Eriochrome Black T (EBT) was studied by batch experiments. The results showed that the highest adsorption capacity was obtained in acidic medium (pH = 5), and the pseudo-second-order model fitted well with the experimental data indicating the rate-determining step mainly determined by chemisorption. The adsorption equilibrium data followed better the Freundlich isotherm model with multi-layered adsorption compared to the Langmuir isotherm model. Thermodynamic parameters indicated that the adsorption of EBT onto β-CDBEP was an endothermic and spontaneous process, and a favorable adsorption happened at a relatively higher temperature. The combined electrostatic interactions, inclusion complexation, π-π interactions and intra-particle diffusion contributed to the adsorption of EBT onto β-CDBEP.