Engineered zirconia nanomaterials for circular environmental and nuclear applications: dual-function design for photocatalytic pollutant degradation and gamma-ray shielding

This work introduces a sustainable strategy for synthesizing multifunctional zirconia (ZrO₂)-based nanomaterials doped with Fe, Ba, and B via a green hydrothermal method. These materials demonstrate dual functionality: first, they serve as efficient photocatalysts for the degradation of organic pollutants like Rhodamine B (RhB) under UV light, achieving removal efficiencies of 65% (ZrO₂), 91% (B-ZrO₂), 95% (Fe-ZrO₂), and 99% (Ba-ZrO₂) within 30 min. After their photocatalytic use, the same nanomaterials are repurposed as gamma-ray shielding agents. Structural characterization revealed crystallite sizes ranging from 53.3 to 61.4 nm and densities up to 6.67 g/cm³ (Fe-ZrO₂). The γ-ray protection capacity of the synthesized nanocomposites was evaluated using the experimental measurements by the NaI(Tl) detector and radioactive sources emitting energies bounded by 0.245 and 1.408 MeV. The experimentally recorded data were validated using the Monte Carlo simulation over the same mentioned energy interval. Both simulated and experimentally measured data confirm that the γ-ray attenuation performance was highest for Fe-ZrO₂, with linear attenuation coefficients decreasing from 0.978 ± 0.043 to 0.333 ± 0.012 cm^–1 as the γ-ray energy raised from 0.245 to 1.408 MeV. In comparison, undoped ZrO₂ exhibited lower LACs in the range of 0.810 ± 0.036 to 0.277 ± 0.010 cm^–1. This dual-use model exemplifies a circular material lifecycle, enhancing environmental remediation while enabling post-use recycling for radiological protection.