Capture of radioactive cations from water using niobate nanomaterials with layered and tunnel structures

Abstract

Niobates with one-dimensional (1D) morphology, layered KNb3O8 nanorods and tunnel structured Na2Nb2O6·H2O nanofibers, are fabricated readily by a reaction between niobium oxide and alkali hydroxides under hydrothermal conditions. They exhibit ideal properties for removal of radioactive cations such as Sr2+, Ba2+ (as simulant for 226Ra2+) and Cs+ ions from wastewater through an ion exchange process. Compared with the Na2Nb2O6·H2O nanofibers, the KNb3O8 nanorods displayed better performance for the irreversible entrapment of the toxic cations, particularly Ba2+ cations, due to the deformation of the layer structure. Besides, these 1D niobates are acid resistant with selective uptake of the radioactive cations in the presence of a large excess of K+ or Na+ ions.