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Synthesis of Tributyl Phosphate-Coated Hydroxyapatite for Selective Uranium Removal
Kim, HyunJu,Um, Wooyong,Kim, Won-Seok,Chang, Seeun American Chemical Society 2017 INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH - Vol.56 No.12
<P>Efficient and rapid removal of radioactive contaminants is crucial when they are released into the environment following nuclear accidents. Here, different types of apatite were synthesized using tributyl phosphate (TBP) and tested for the removal of uranium from various solutions using different reaction times and uranium concentrations. The uranium adsorption results showed that uranium adsorption reached a steady state within 24 h in tests open to atmosphere at a slightly alkaline pH in different background solutions. TBP-coated hydroxyapatite removed U better than hydroxyapatite alone did. The U removal mechanism was considered as multilayer adsorption, showing the best fit to the Freundlich isotherm. The maximal U adsorption capacity determined from the Langmuir isotherm is 38 mg of U g<SUP>–1</SUP>. Because of the high U removal efficiency, even at the high pH used in this study, TBP-coated hydroxyapatite appears to be a promising adsorbent for the removal of U from various waste streams as well as for recovery of U from seawater.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/iecred/2017/iecred.2017.56.issue-12/acs.iecr.6b04491/production/images/medium/ie-2016-04491f_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ie6b04491'>ACS Electronic Supporting Info</A></P>
Kim, Won-Seok,Nam, Seongsik,Chang, Seeun,Kim, HyunJu,Um, Wooyong THE KOREAN SOCIETY OF INDUSTRIAL AND ENGINEERING 2018 JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY -S Vol.57 No.-
<P><B>Abstract</B></P> <P>Decontamination techniques proposed and used to remove Chalk River unidentified deposit (CRUD) in radioactive waste management. In cases of huge volumes of metal or radionuclides contaminated by CRUD, removal of CRUD by mechanical or chemical decontamination is difficult. An advanced electrokinetic process combined with chemical decontamination was applied to remove CRUD and experimentally evaluated. Oxalic acid was used for CRUD removal, and cobalt (Co) released from the CRUD was transferred to the cathode in an electrokinetic reactor. Results indicate that the combined system is efficient for CRUD removal with enhanced, efficiency by use of the cation exchange membrane and zeolite.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Combined decontamination method was developed for CRUD removal. </LI> <LI> Chemical reagent and EK processes were combined to enhance the removal efficiency. </LI> <LI> A huge volume of contaminated metals from NPPs was reduced after decontamination. </LI> <LI> Cobalt ions were removed by zeolite in the EK process after moving to the cathode. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
pH-Dependent Composition Analysis of Nickel-Chelate Complexes Using UV-Vis Spectrophotometry
Seeun Kim,Yujin Jeong,Jinkyu Park 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.2
Chelating agents like ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), and nitrilotriacetic acid (NTA) find extensive application in the removal of residual substances due to their high stability constants with a wide range of metal ions. They also play a crucial role in nuclear decontamination operations aimed at eliminating metallic radionuclides such as 60Co, 90Sr, and 239Pu. However, improper disposal of chelated radioactive waste can lead to significant increases in radionuclide migration rates from disposal sites. Therefore, it is imperative to comprehend the behavior of chelating agents under varying conditions, including pH, temperature, and metal ion concentrations. In this study, we present the results of a pH-dependent composition analysis of nickel-chelate complexes using UV-Vis spectrophotometry. Nickel (Ni) serves as an ideal metal ion for investigating its interactions with chelating agents due to its solubility over a wide pH range and high stability constants with all three chelating agents mentioned earlier. Initially, UV-Vis spectra of Ni-EDTA, Ni-DTPA, and Ni-NTA complexes were recorded at various pH levels. We assigned absorption maxima and compared our findings with existing literature on each Ni-chelate complex. Furthermore, we examined mixed samples of all three complexes, varying the pH to monitor changes in composition. The results and their implications will be presented in our poster presentation.
Recent progress in oxygen electrodes for protonic ceramic electrochemical cells
Oh Seeun,Kim Hyeonggeun,Jeong Incheol,Kim Dongyeon,Yu Hyeongmin,Lee Kang Taek 한국세라믹학회 2024 한국세라믹학회지 Vol.61 No.2
Protonic ceramic electrochemical cells, a promising technology for energy conversion and storage, have garnered significant interest in recent years owing to their superior low-temperature (< 600 °C) performance relative to solid oxide electrochemical cells. However, the sluggish kinetics of oxygen electrodes have impeded further advancements. Despite considerable research efforts, the development of practically applicable oxygen electrodes remains challenging. We herein review the recent research focusing on the fundamental understanding and development of oxygen electrode materials. Furthermore, we provide a range of material design strategies for enhancing the catalytic activity of oxygen electrodes along with a concise overview of potential derivative applications. Finally, the perspectives and potential directions for the development of oxygen electrodes for high-performance protonic ceramic electrochemical cells are presented.