The Poly(acrylonitrule-co-acrylic acid)-graft-β-cyclodextrin Hydrogel for Thorium(IV) Adsorption

In this report, the β-CD(AN-co-AA) hydrogel was used to remove the thorium(IV) [Th(IV)] from the water system, and the new adsorbent was characterized through Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The influences of contact time, pH value, ionic strength, solid-liquid ratio, initial Th(IV) concentration, and temperature on Th(IV) adsorption onto the functional hydrogel were researched. The results showed that the experimental data followed the Langmuir isotherm and the maximum adsorption capacity (q_max) for Th(IV) was 692 mg/g at pH 2.95, which approached the calculated (q_e) 682 mg/g. The desorption capacity of Th(IV) in different HNO₃ concentrations ranging from 0.005 to 0.5 M was also studied, and the percentage of the maximum desorption was 86.85% in the condition of 0.09 M HNO₃. The selectivity of β-CD(AN-co-AA) hydrogel was also be studied, the results indicated that this material retained the good adsorption capacity to Th(IV) even when the Ca²⁺, Mg²⁺, or Pb²⁺ existed in the system. The findings indicate that β-CD(AN-co-AA) can be used as a new candidate for the enrichment and separation of Th(IV), or its analogue actinides, from large-volume solution in practical application.