Magnetic-supported cucurbituril: A recyclable adsorbent for the removal of humic acid from simulated water

Magnetic cucurbituril (MQ[n]), a new functional material compound, was prepared via chemical co-precipitation method as a high-capacity adsorbent for humic acid (HA). The material was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and thermal gravimetric analysis (TGA), respectively, indicating that Q[n] has been grafted on the surface of Fe3O4. Its adsorption-desorption behaviour towards HA from aqueous solution have been investigated. MQ[n] demonstrated good adsorption capacity at pH 7 in adsorption experiments. Adsorption isotherm could be well interpreted by the Freundlich isotherm model. Adsorption kinetic followed pseudo-second-order kinetics, which indicated that the limit factor of adsorption HA was adsorption mechanism. The negative value of thermodynamic parameters showed that adsorption process was spontaneous and exothermic. Moreover, the capacity of MQ[n] was also above 80% after being used for four times, so it may have potential industrial applications.