Uranium and Thorium water decontamination via novel coated Cu-based nanoparticles; the role of chemistry and environmental implications

Abstract

The removal of radioactive contaminants from aquifers is a matter of great concern. In this paper, coated copper-based nanoparticles (Cu-based NPs) were investigated as sorbent materials to remove uranium and thorium from low-level wastes, and especially from water, considering the influences of temperature, time, concentration, and pH. Cu-based NPs were derived through a hydrothermal synthesis from copper nitrate degradation in the presence of the bifunctional with COOH-terminated PEG, TEG as well as PEG 8000. The characterization was undertaken using XRD, TEM, TG/DTG, FTIR, and SEM-EDS. Isotherm models such as Langmuir and Freundlich were applied, while kinetic data were successfully reproduced by the pseudo-second-order equation and thermodynamic parameters were calculated. To investigate the removal mechanisms, UV-fluorescence and X-ray photoelectron spectroscopy were used. In the case of uranium, the predominant mechanism includes the formation of surface complexes, followed by extensive reduction (65%) of U(VI) to less soluble U(IV) while in the case of thorium, surface precipitation dominates. Copper nanoparticles exhibited significant U(VI) uptake capacity resulting in a decrease of the U-concentration below the acceptable limit of 30 μg/L and can be successfully applied in water treatment technology.

Keywords: Copper nanoparticles; Sorption; Thorium; Uranium; Water decontamination.