Fabrication of carboxymethyl functionalized β-cyclodextrin-modified graphene oxide for efficient removal of methylene blue

Abstract

In this study, a novel carboxymethyl functionalized β-cyclodextrin-modified graphene oxide (CM-β-CD-GO) adsorbent was designed and fabricated. The CM-β-CD-GO was applied to remove methylene blue (MB) from aqueous solutions. The adsorption mechanism was discussed in detail through the study of pH effect, kinetics, and isotherm models. The adsorption of CM-β-CD-GO for MB displayed high removal rates at the pH range of 6.0–10.0, and the removal efficiency is over 90% within 20 min. The pseudo-second-order model could well describe the kinetic process of MB adsorption, and the adsorption was determined by the multi-step process. The maximum uptake capability of CM-β-CD-GO towards MB was 245.70 mg g−1 at 25 °C according to Langmuir isotherm model. A possible adsorption mechanism that electrostatic attraction, π-π interaction, and host-guest supramolecular interactions supported MB adsorption was proposed. The adsorption capacity of CM-β-CD-GO showed no significant change after five cycles. The structure and morphology of CM-β-CD-GO were characterized by XPS, FT-IR, TGA, PXRD, AFM, SEM, zeta (ζ) potential determination, and Raman spectroscopy. This work provides valuable information for the design of novel adsorbents that specifically and efficiently adsorb cationic dyes contaminants.

Keywords

• Graphene oxide
• β-Cyclodextrin
• Carboxymethylated modification
• Adsorption
• Methylene blue