Facile preparation of core-shell structure β-cyclodextrin/diatomite as an efficient adsorbent for methylene blue

Abstract A core-shell structure based on β-cyclodextrin/diatomite (β-CD-DE) was formed via a facile and mild-conditioned emulsion polymerization of β-CD coated with DE. The structure and morphology of β-CD-DE was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). Various controlling parameters were monitored during the static adsorption processes, including adsorption time, temperature, pH, β-CD-DE concentration and initial MB concentration. Under optimal temperature and pH conditions (20 °C and pH value of 7), a high adsorption capacity (90.0 mg·g-1) and high partition coefficient (120.4 mg·g-1·μM-1) at 10% BT for dynamic adsorption was obtained for β-CD-DE at an initial MB concentration of 100 mg·L-1. Subsequently, thermodynamic and kinetic fitting revealed that the adsorption process can be described by a Langmuir model and pseudo-first-order kinetic model, which indicates a spontaneous exothermic and physical adsorption. The maximum adsorption capacity was found to reach up to 271.7 mg·g-1, with the adsorption capacity in the fifth cycle still retaining 95.1% (258.4 mg·g-1) of the adsorption capacity of the first cycle.