Preparation of water-soluble β-cyclodextrin/poly(acrylic acid)/graphene oxide nanocomposites as new adsorbents to remove cationic dyes from aqueous solutions

Novel nanocomposites of β-cyclodextrin/poly(acrylic acid) grafted onto graphene oxide (β-CD/PAA/GO) were successfully synthesized for the first time using an esterification reaction, and they were used to remove the cationic dyes methylene blue (MB) and safranine T (ST) from aqueous solutions. The as-prepared β-CD/PAA/GO nanocomposites were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction analysis. The β-CD/PAA/GO nanocomposites showed excellent water dispersibility because of the hydrophilicity of the polymer. The adsorption isotherms fitted the Langmuir isotherm model. The maximum adsorption capacities were 247.99 mg g−1 for MB and 175.49 mg g−1 for ST, and these are much higher than those of other carbon-based adsorbents that have been described in the literature. This was attributed to the high concentration of functional groups in the nanocomposites. Repeated MB and ST adsorption and desorption cycles showed that the β-CD/PAA/GO nanocomposites could be used repeatedly, and their adsorption capacities did not change significantly after five cycles. The fast and efficient adsorption of MB and ST by the β-CD/PAA/GO nanocomposites from aqueous solutions suggested that these novel nanocomposites may be ideal candidates for removing dyes during water treatment.