Deciphering the facet-dependent scavenging potential of -Fe₂O₃ nanocrystals for U(VI) and Eu(III) from aqueous phase

The utilization of biocompatible and inexpensive adsorbents for the effective scavenging of U(VI) and Eu(III) from wastewater is still an open challenge in nuclear waste management. Herein, three kinds of alpha-Fe2O3 nanocrystals with different morphologies, i.e., alpha-Fe2O3 nanospheres (HNSs), nanoplates (HNPs) and nanorods (HNRs), which were exposed (102), (001), and (110) facet, respectively, was used to scavenge U(VI) and Eu(III) from aqueous solutions via an adsorption procedure. Various techniques of N-2 adsorption-desorption, FT-IR, XRD, XPS, TEM, SEM and EDS were applied to characterize these adsorbents before or after adsorption. The results indicated that the adsorption capacity of U(VI) and Eu(III) was in the order of HNPs (001) > HNRs (1 1 0) > HNSs (102), namely, alpha-Fe2O3 nanoplates was proved to be a good adsorbents, with removal capacity of 221 mg/g and 131 mg/g for U(VI) and Eu(III) scavenged on HNPs, respectively. The kinetics of U(VI) and Eu(III) scavenging agreed with the pseudo second order kinetic model, suggesting that chemical interaction is mainly responsible for U(VI) and Eu(III) scavenging on these materials. Furthermore, the Freundlich model fit the best for adsorption isotherms of U(VI) and Eu(III). The present study demonstrated that these alpha-Fe2O3 nanocrystals are promising materials in nuclear waste management.