Sulfate-Rich Metal–Organic Framework for High Efficiency and Selective Removal of Barium from Nuclear Wastewater

Capture of radioactive barium from nuclear wastewater is of great importance for environmental protection. Here, [Zr6(OH)10.8(SO4)3.6(BDC-NH2)3(H2O)7.4]·nH2O (Zr-BDC-NH2-SO4) was selected as an adsorbent for its high content of sulfate group, which is a strong barium-chelating group, and its binding sites are fully exposed. Zr-BDC-NH2-SO4 exhibits high adsorption capacity of 181.8 mg g–1, which is higher than those of most reported adsorbents, and showed excellent high selectivity even when the concentrations of background metal ions are 10 times of Ba2+. The breakthrough study showed good adsorption performance with fast kinetics and low outlet concentration. In addition, the great stability of Zr-BDC-NH2-SO4 under γ radiation has been confirmed, making it possible to be applied in real nuclear wastewater treatment. Moreover, the adsorption of Ba2+ is irreversible and therefore it could avoid secondary pollution. Overall, this work provides a stable, efficiency adsorbent for removing radioactive barium from nuclear wastewater.