In order to promote the sustainable development of nuclear
energy
through thorium (Th(IV)) recycling, we synthesized SiO2-coated magnetic functional nanocomposites (SiO2@Fe3O4) that were modified with 2,9-diamide-1,10-phenanthroline
(DAPhen) to serve as an adsorbent for Th(IV) removal. SiO2@Fe3O4-DAPhen showed effective Th(IV) adsorption
in both weakly and strongly acidic solutions. Owing to its porous
structure that facilitated rapid adsorption kinetics, equilibrium
was achieved within 5 and 0.5 min at pH 3 and 1 mol L–1 HNO3, respectively. In weakly acidic solutions, Th(IV)
primarily formed chemical coordination bonds with DAPhen groups, while
in strongly acidic solutions, the dominant interaction was electrostatic
attraction. Density functional theory (DFT) calculations indicated
that electrostatic attraction was weaker compared to chemical coordination,
resulting in reduced diffusion resistance and consequently faster
adsorption rates in strongly acidic solutions. Furthermore, SiO2@Fe3O4-DAPhen exhibited a high adsorption
capacity for Th(IV); it removed Th(IV) through chelation and electrostatic
attraction at pH 3 and 1 mol L–1 HNO3, with maximum adsorption capacities of 833.3 and 1465.7 mg g–1, respectively. SiO2@Fe3O4-DAPhen also demonstrated excellent tolerance to salinity,
adsorption selectivity, and radiation resistance, thereby highlighting
its practical potential for Th(IV) removal in diverse contaminated
water sources. Hence, SiO2@Fe3O4-DAPhen
represents a promising choice for the rapid and efficient removal
of Th(IV).