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A Study on the pH Speciation and Stability Constants for Chelating Agents With Metals
Hwakyeung Jeong,Byungman Kang,Hyejin Cho,Jihye Kim 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.2
Chelating agents, such as ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), and nitrilotriacetic acid (NTA) are widely used in industry and agriculture as water softeners, detergents, and metal chelating agents. In wastewater treatment plants, a significant amount of chelating agents can be discharged into natural waters because they are difficult to degrade. Since those compounds affect the mobility of radionuclides or heavy metals in decontamination operations at nuclear facilities and radioactive waste disposal, quantification of the amount of ligand is very important for safe nuclear waste management. To predict the behavior of the main complexation in sample matrices of radioactive wastes, it is essential to evaluate the distribution of the metal-chelating species and their stabilities in order to develop analytical techniques for quantifying chelating agents. We have investigated to collect information on the pH speciation of metal chelation and the stability constants of metal complexes depending on three chelating agents (EDTA, DTPA, and NTA). For example, Zhang’s group recently reported that the initial coordination pH of Cu(II) and EDTA4? is delayed with the addition of Fe(III), and the pH range for the stable existence of [Cu(EDTA)]2? is narrowed compared to when it is alone in the sample matrix. The addition of Fe(III) clearly impacts the chemical states of the Cu(II)-EDTA solution. Additionally, Eivazihollagh’s group demonstrated differences in the speciation and stability of Cu(II) species between Cu(II) and three chelating ligands (EDTA, DTPA, and NTA). This study will be greatly helpful in identifying the sample matrix for binding major chelating agents and metals as well as developing chemically sample pretreatment and separation methods based on the sample matrix. Finally, these advancements will enable reliable quantitative analysis of chelating agents in decommissioning radioactive wastes.
Sojin Jeong,Hanul Cho,Byungman Kang,Jihye Kim,Sang Ho Lim 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.2
During the initial cooling period of spent nuclear fuel, Cs-137 and Sr-90 constitute a large portion of the total decay heat. Therefore, separating cesium and strontium from spent nuclear fuel can significantly decrease decay heat and facilitate disposition. This study presents analytical technique based on the gas pressurized extraction chromatography (GPEC) system with cation exchange resin for the separation of Sr, Cs, and Ba. GPEC is a micro-scaled column chromatography system that allows for faster separation and reduction volume of elution solvent compared to conventional column chromatography by utilizing pressurized nitrogen gas. Here, we demonstrate the comparative study of the conventional column chromatography and the GPEC method. Cation exchange resin AG 50W-X12 (200~400 mesh size) was used. The sample was prepared at a 0.8 M hydrochloric acid solution and gradient elution was applied. In this case, we used the natural isotopes 88Sr, 133Cs, and 138Ba instead of radioactive isotopes for the preliminary test. Usually, cesium is difficult to measure with ICP-OES, because its wavelengths (455.531 nm and 459.320 nm) are less sensitive. So, we used ICP-MS to determine the identification and the recovery of eluate. In this study, optimized experimental conditions and analytical result including reproducibility of the recovery, total analysis time and volume of eluents will be discussed by comparing GPEC and conventional column chromatography.
Sojin Jeong,Hanul Cho,Byungman Kang,Sang Ho Lim,Jihye Kim 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1
This study was performed to evaluate the separation of Sr, Cs, Ba, La, Ce, and Nd using gas pressurized extraction chromatography (GPEC) with anion exchange resin for the quantitation of Neodymium. GPEC is a micro-scaled column chromatography system that provides a constant flow rate by utilizing nitrogen gas. It is overcome the disadvantages of conventional column chromatography by reducing the volume of elution solvent and shortening the analysis time. Here, we compared the conventional column chromatography and the GPEC method. The whole analysis time was decreased by nine times and radioactive wastes were reduced by five times using the GPEC system. Anion exchange resin 1-X4 (200~400 mesh size) was used. The sample was prepared at a 0.8 M nitric acid in methanol solution. The elution solvent was used at a 0.01 M nitric acid in methanol solution. Finally the eluate was analyzed by ICP-MS to determine the identification and recovery. In this case, we applied the natural isotopes of LREEs (139La, 140Ce, and 144Nd) and high activity nuclides (88Sr, 133Cs, and 138Ba) instead of radioactive isotopes for the preliminary test; as a result, unnecessary radioactive waste was not produced. The recoveries were 93.9%, 105.9%, 91.9%, 47.6%, 35.9%, and 79.9% of Sr, Cs, Ba, La, Ce, and Nd, respectively. The reproducibility of recoveries by GPEC were in the range 2.8%–10.9%.
Development of Protein-Resistant Hydrogels via Surface Modification with Dendritic PEGs
Lee, Cheol Woo,Kang, Byungman,Kim, Ho-Joong,Ryu, Geun Chang American Scientific Publishers 2016 Journal of Nanoscience and Nanotechnology Vol.16 No.11
<P>This report describes the synthesis and characterization of a series of poly(2-hydroxyethylmethacrylate) (pHEMA)-based hydrogel lenses coated with poly(ethylene glycol) (PEG) chains. We synthesized a novel dendritic tribranched PEG chain, which provides a densely packed PEG coating on the hydrogel surface, to investigate whether a branched architecture leads to reduced protein adsorption. The protein adsorption, water content, optical transparency, and surface hydrophilicity properties of the hydrogels were investigated. The PEG-coated hydrogels showed 90% transmittance and improved surface hydrophilicity. In particular, the amount of protein adsorbed on the dendritic PEG-coated hydrogels decreased significantly relative to the amounts adsorbed onto the surfaces of unmodified and linear PEG-coated hydrogels. This new example of dendritic PEG-coated hydrogels is believed to have potential for future biomedical and ophthalmic applications because of their biocompatibility and antifouling properties.</P>
박철수(Chulsoo Park),장병만(Byungman Chang),강필성(Pilsung Kang) 한국경영과학회 2015 經營 科學 Vol.32 No.4
Partner relationship management (PRM) refers to processes and methodologies associated with managing the relationship between corporations and their partners. Recently, the importance of PRM has been increasingly emphasized, and it is considered as a core competitive factor for firms whose sales heavily rely on the intermediate distributor. In this paper, we identify key success factors for PRM system based on literature review on CRM system and interviews with domain experts, and prioritize them from two different perspectives, firms and partners, based on analytical hierarchy process. Partners responded that trust-building between firms and partners, quality of system, and satisfaction level for information system have high priorities, while firms responded that quality of system, information share, and trust building between firms and partners. Identified factors and evaluated priorities can provide a strategic guideline when planning the PRM system building.