The effective removal of nickel ions from aqueous solution onto magnetic multi-walled carbon nanotubes modified by β-cyclodextrin

Abstract

β-cyclodextrin was covalently grafted onto the surface of magnetic multi-walled carbon nanotubes to synthesize a novel composite material (denoted as β-CD@Fe3O4/MWCNT). The structure of the magnetic material was characterized by using Fourier transform infrared (FT-IR spectroscopy), Raman spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and specific surface area (BET). The results from SEM showed that the dispersion of carbon nanotubes was better after β-cyclodextrin was compounded. TGA indicated that about 7.1% of the β-cyclodextrin was grafted onto the surface of the magnetic carbon nanotubes. In addition, β-CD@Fe3O4/MWCNT had larger specific surface area and pore volume. The adsorption of nickel ions on β-CD@Fe3O4/MWCNT was affected by pH, temperature and adsorption time. The pseudo-second-order kinetic model and Langmuir model describe the adsorption process well. Thermodynamic data showed that the adsorption process was spontaneous and exothermic, and the maximum adsorption amount of nickel ions (Ni2+) on the β-CD@Fe3O4/MWCNT was 103 mg g−1 at room temperature. Moreover, regeneration experiments showed that the adsorbent still maintained a high adsorption capacity after 5 cycles. On this basis, the interaction mechanism between magnetic nanoparticles and Ni2+ was discussed. In summary, as an environmentally friendly adsorbent, β-CD@Fe3O4/MWCNT has the potential to remove nickel ions from wastewater.