- Published in the scientific journal Journal of Hazardous Materials (IF 12.2, JCR Rank: top 3.5% in the field of environmental science) -

The research team of Professor Cho-eun Jong (first author) and Professor Min Jang (corresponding author, deputy director of PBRC, and director of the Environmental Nanotechnology Laboratory (JENTL²)) from the Department of Environmental Engineering, together with Professor Yoon-Young Jang, Professor Jae-Gyu Yang, and Professor Eun-Ha Choi (director of PBRC) from the Department of Electrical & Biological Physics, developed a material that can adsorb and remove uranium (U) from water with high efficiency. According to a 2022 report from Yonhap News¹, uranium, a radioactive substance, was detected at levels above the safety standard in 2% of the groundwater wells dug by individuals for drinking water. The Ministry of Environment and the National Institute of Environmental Research announced that, out of 7,036 private groundwater wells surveyed, 2.1% (148 wells) exceeded the uranium safety standard of 30 ？g per liter. As a result, urgent water treatment has been recognized as necessary.

The research team developed a manufacturing method by first producing granulated 3D graphene oxide (3D-GO), then doping and synthesizing the metal-organic framework (MOF) UiO-66 onto the 3D-GO. In the U(VI) adsorption isotherm experiment, the adsorbent containing 10% UiO-66 (3D-GO/U-10) demonstrated a very high adsorption capacity of 375.5 mg/g and maintained strong U(VI) adsorption performance across a wide pH range. Interestingly, when UiO-66 was introduced to the 3D-GO, the UiO-66 particles did not agglomerate and were evenly doped.

Through in-situ surface-enhanced Raman spectra and density functional theory simulations, it was found that the Zr-O₂ structure in UiO-66, with a symmetric metal at the center, has the highest adsorption energy for U(VI) (-3.21 eV). The electron transfer from the oxygen atom to U(VI) induces covalent bonding between the Zr-O₂ in 3D-GO/U-10 and U(VI). The 3D-GO/U-10 saturated with U(VI) achieved a very high regeneration efficiency over five regeneration cycles using a 0.1 M Na₂CO₃/0.01 M H₂O₂ solution, with a U(VI) removal rate of 89.7% on the fifth regeneration. In continuous flow column experiments, 3D-GO/U-10 consistently maintained approximately ~76% of its U(VI) removal capacity over a maximum of four column cycles. The high-efficiency adsorbent developed in this project can selectively adsorb U(VI) in various environments, demonstrating potential for treating uranium in actual groundwater.

This research was supported by the Ministry of Environment (Grant 2020002470002) and the National Research Foundation of Korea (University Research Center 2021R1A6A1A03038785, Mid-Career Researcher Program 2023R1A2C1003464, and Research Staff Program RS-2023-00240726). The research results were published online in July 2024 in the scientific journal Journal of Hazardous Materials (IF: 12.2) under the title 'Fabrication of Granular Three-Dimensional Graphene Oxide/UiO-66 Adsorbent for High Uranium Adsorption: Density Functional Theory and Fixed Bed Column Studies.'

¹ Yonhap News: https://www.yna.co.kr/view/AKR20220728057000530

² JENTL Website: https://www.jentl.net/

Web link: https://doi.org/10.1016/j.jhazmat.2024.135237