Preparation of β-cyclodextrin-modified multi-walled CNTs and its application in capturing βb-naphthol from wastewater

Multi-walled carbon nanotubes (MWCNTs) were covalently modified with water-soluble β-cyclodextrin (β-CD) through ester bond. The products cyclodextrin-modified multi-walled carbon nanotubes (MWCNTs-COO-CD) were characterised by ¹H-NMR, Fourier transform infrared spectroscopy and thermogravimetric analysis. The solubility of MWCNTs-COO-CD in water was 357.3 mg/l and no precipitates were observed after 18 months. The fluorescence spectra proved that the MWCNTs-COO-CD as a spectral probe could be used in the molecular recognition of β-naphthol (β-NOH), and the effective association constant (K_a) was calculated 2.22×10⁴ from fluorescence spectra. By centrifugation at a speed of 16 000 rpm/min, the β-NOH with MWCNTs-COO-CD could be separated from water, collected and reused repeatedly. The results showed that the MWCNTs-COO-CD could be used to capture the aromatic pollutant such as β-NOH from wastewater. This study will widen the application of nanosupramolecule materials.