The initial radionuclide migration quantity depends on the total amount of solubilized species. Geochemical modeling based on a thermodynamic database (TDB) has been employed to assess the solubility of radionuclides. It is necessary to evaluate whether the TDB describes the domestic repository conditions appropriately. An effective way to validate the TDB-based modeling results is through direct comparisons with experimentally measured values under the conditions of interest. Here, the solubilities of trivalent Sm, Eu, and Am were measured in synthetic KURT-DB3 groundwater (Syn- DB3) and compared with modeling results based on ThermoChimie TDB. Ln2(CO3)3·xH2O(cr) (Ln = Sm, Eu) solids were introduced into the Syn-DB3 and dissolved Sm and Eu concentrations were monitored over 223 days. X-ray diffraction analysis confirmed that the crystallinity of the solid compounds was maintained throughout the experiments. The dissolved Sm and Eu concentrations at equilibrium were close to the predicted solubilities of Sm2(CO3)3(s) and Eu2(CO3)3(s) based on the ThermoChimie TDB. The Am solubility measured under oversaturated conditions was comparable to the measured Eu concentrations, although they were measured under different experimental settings. More experimental data are needed for Am-carbonate solid systems with careful characterization of the solid phases to better evaluate Am solubility in domestic groundwater conditions.

유통 중인 생분해성 합성수지로 만들어진 식품용 기구 및 위생용품 50건을 대상으로 ‘식품용 기구 및 용기·포장 공전’의 기준·규격을 검사하였다. PLA 재질의 유아식기 1 건에서 ‘과망간산칼륨소비량’이 20mg/L으로 기준치(10 mg/ L 이하)를 초과하였고, 그 외 모든 시료에서는 포름알데히 드, 납, 비소 등이 기준·규격 이하로 안전한 수준이었다. 또한 가정에서 유아식기를 소독하는 방법의 안전성을 조 사하기 위해, PLA 재질의 유아식기(n=21)에서 반복적인 열탕소독과 자외선 조사에 따른 이행량의 변화를 조사하였다. 반복적인 열탕소독이 자외선 조사에 비해 포름알데 히드와 비소의 이행량이 많았으나, 이행량은 매우 낮은 수 준이었다. 그리고 유아(만 1-3세) 기준으로 계산한 포름알 데히드와 비소의 일일추정섭취량(EDI)은 최대 6.0×10-4mg/ kg b.w./day 및 1.3×10-1 μg/kg b.w./day였으며, 이는 일일섭 취한계량(TDI, 0.15 mg/kg b.w./day) 및 잠정주간섭취허용 량(PTWI, 9.0 μg/kg b.w./week)의 0.40% 및 10.42%로 낮 은 수준임을 확인하였다. 따라서 현 국내에서 유통되고 있 는 식품용 생분해성 합성수지제는 안전한 수준임을 확인 하였다.

Over the last decade, there has been growing interest in the plastic degradation capabilities of insect because herbivorous insects may be a valuable resource for microorganisms that can break down synthetic plastics. Insects that can digest plastics using their gut microbiota are gaining interest for use in bioremediation, although their environmental benefits remain unknown. However, most plastics biodegraded by insect gut microbes are polyethylene, polystyrene with little knowledge available on the gut microbiome of insects capable of degrading other synthetic plastics. Therefore, there is an urgent need to secure microbial resources based on insect-microbiome interactions and promote end-of-life solutions for synthetic plastics.

Graphene quantum dots (GQDs) are zero-dimensional carbonous materials with exceptional physical and chemical properties such as a tuneable band gap, good conductivity, quantum confinement, and edge effect. The introduction of GQDs in various layers of solar cells (SCs) such as hole transport layer (HTL), electron transport materials (ETM), cathode interlayer (CIL), photoanode materials (PAM), counter electrode (CE), and transparent conducting electrode (TCE) could improve the solar energy (SE) harvesting, separation and transportation of electrons and hole, thus ultimately enhance the overall performance and stability of SCs. The incorporation of GQDs in various layers such as HTL, ETM, CIL, PAM, CE, and TCE achieved photo conversion efficiencies (PCEs) of 18.63, 21.1, 12.81, 9.41, 8.1, and 3.66%, respectively. Furthermore, GQDs improved stabilities such as resistance to degradation for HTL (up to 77%), ETM (80%), resistance to UV light for ETM (94%), resistance to temperature in ETM (90%), and bending stabilities after 1000 cycles for HTL (88%) and for TCE (90%). There are reviews focused on the utilization of different carbon-structured materials such as graphene, carbon nanotubes (CNT), fullerenes, and carbon dots in SCs applications. More specifically, the utilization of GQDs for SCs is limited and yet to be explored in greater detail. This review mainly focuses on the recent advancement of various techniques of production of GQDs synthesis, utilization of GQDs in various layers like HTL, ETM, CIL, PAM, CE, and TCE for the enhancement of PCE, and the stability of SCs. As a result, we believe that an exclusive study on GQDs-sensitized solar cells (GQDSSCs) could provide an in-depth analysis of the recent progress, achievements, and challenges.

Fluorine (F) recovery from wet process phosphoric acid (WPA) is essential for sustainable resource utilization and environmental protection. This work systematically investigates the F recovery mechanism by air stripping from three simulated systems: H3PO4- H2SiF6-H2O, H3PO4- HF-H2O, H3PO4- H2SiF6-HF-Al3+-H2O, and from two industrial systems: WPA and WPA-Al3+ under different stripping temperatures (60–110 ℃) and stripping times (0–120 min). The influence on the existence form of F, the content of Al3+ cations and the addition of active silica on the F removal rate in the phosphoric acid solution is studied by analyzing the changes in the contents of F, P and Si. The results indicate that the F in the form of H2SiF6 is more easily released from the phosphoric acid solution than that in the form of HF. While, the release of F is inhibited in the presence of the Al3+ in the solution due to the formation of Al-F complexes that are characterized by 19F NMR, 31Si NMR and FTIR techniques. Interestingly, the addition of active silica can promote the conversion of HF to H2SiF6 in the solution and significantly improve the release rate of F. The researching results can provide an important guidance for industrial practice of WPA.

The disposal of spent nuclear fuel (SNF) in a deep geological repository (DGR) is a widely accepted strategy for the long-term sequestration of radiotoxic SNF. Ensuring the safety of a DGR requires the prediction of various reactions and migration behaviors of radionuclides (RNs) present in SNF within its geochemical surroundings. Understanding the dissolution behaviors of mineral phases harboring these RNs is crucial, as the levels of RNs in groundwater are basically linked to the solubility of these solid phases. Accurate measurements of solubility demand the use of welldefined solid materials characterized by chemical compositions and structures. Herein, we attempted the synthesis of sklodowskite, a magnesium-uranyl (U(VI))-silicate, employing a twostep hydrothermal synthetic approach documented previously. Subsequently, we subjected this synthesized sklodowskite to various analytical techniques, including powder X-ray diffraction (pXRD), scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDX), and vibrational spectroscopies (FTIR and Raman). Based on our findings, we confidently identify the obtained mineral phase as sklodowskite (Mg[UO2SiO3OH]2·5H2O). This identification is primarily based on the similarity between its pXRD pattern and the reference XRD pattern of sklodowskite. Furthermore, the measured infrared and Raman spectra show the vibrational modes of UO2 2+ and SiO4 4- ions, particularly within the 700~1,100 cm-1 region, which support that the synthetic mineral has a characteristic layered uranyl-silicate structure of crystalline sklodowskite. Finally, we utilized synthetic minerals to estimate its solubility up to about three months in a model groundwater, where the dissolved species composition is analogous to that of granitic groundwater from the KAERI Underground Research Tunnel. In this presentation, we will present in detail the results of spectroscopic characterizations and the methodology employed to assess the solubility of the U(VI)-silicate solid phase.

소형 곤충으로 좁은 틈새에 있는 총채벌레는 종종 살충제 살포에 노출되기 어렵다. 이에 접촉페로몬을 처리하여 은둔행동을 막으려는 행동 교란 방제 전략을 세웠다. 꽃노랑총채벌레(Frankliniella occidentalis)에서 밝혀진 접촉페로몬은 7-methyltricosane (7TM)으로 본 연구에서는 먹이에 이 물질을 처리하여 행동 교란 유무를 생물검정하였다. 이 접촉페로몬은 유충에게 영향을 주지 않았지만 수컷 성충으로 하여금 처리된 먹 이로부터 회피하려는 행동을 유발하였다. 반면에 암컷 성충에게는 오히려 7TM이 처리된 지역으로 이동하는 행동을 유발하였다. 동일한 접촉페 로몬에 대해서 대만총채벌레(Frankliniella intonsa)에서도 유사한 행동 변화가 관찰되었다. 이러한 7TM에 기인한 총채벌레의 행동 변화를 살충 제 처리와 연결하여 고추를 가해하는 총채벌레류를 대상으로 방제효과를 검정하였다. 스피네토람 살충제 단독 처리에 비해 7TM과 혼합하여 처 리하면 총채벌레류 방제효율이 증가하였다. 흥미로운 점은 7TM 단독 처리로도 대만총채벌레 밀도에 일부 감소 효과를 보여 이 물질이 총채벌레 의 행동교란을 주는 것을 뒤받침하였다. 본 연구는 접촉페로몬 처리로 총채벌레의 살충제 회피 행동을 줄여 방제효과를 높인 새로운 해충방제기 술을 제시한다.

Solubility and species distributions of radionuclides in domestic groundwater conditions are required for the safety assessment of deep underground disposal system of spent nuclear fuel (SNF). Minor actinides including Am contribute significant extents to the long-term radiotoxicity of SNF. In this study, the solubility of Am was evaluated in synthetic groundwater (Syn-DB3), which were simulated for the groundwater of the DB3 site in the KAERI Underground Research Tunnel (KURT). Geochemical modeling was performed based on the ThermoChimie_11a (2022) thermochemical database from Andra to estimate the solubility and species distributions of Am in the Syn-DB3 condition. Dissolved Am concentrations in the Syn-DB3 were experimentally measured under oversaturation conditions. Am(III) stock solution in perchlorate media was sequentially diluted in Syn-DB3 to prepare 8 μM Am(III) in Syn-DB3. The pH of the solutions was adjusted to be in the range of 6.4–10.5. A portion of the samples was transferred to quartz cells for UV-Vis absorption and time-resolved laser fluorescence spectroscopy studies and the rest were stored in centrifuge tubes. The absorption spectra of the samples were monitored over 70 days and the results suggest that Am colloidal particles were formed initially in all the samples and precipitated rapidly within two days. Over the experimental period of 236 days, small volume (10 μL) of the samples in the centrifuge tubes were periodically withdrawn after centrifugation (18000 rpm, 1 hr) for the liquid scintillation counting to measure the concentrations of Am dissolved in Syn-DB3. In the end of the experiments, pH of the samples was checked again and the final dissolved Am concentrations were determined after ultrafiltration (10 kDa) to exclude the contribution of colloidal particles. In the pH range of 8-9, which is relevant to the KURT-DB3 groundwater condition, the measured dissolved Am(III) concentrations were converged to around 10-8 M. These values are higher than the solubility of AmCO3OH:0.5H2O(s), but lower than that of AmCO3OH(am). There was no indication of transformation of the amorphous phase to the crystalline phase in our observation time window.

Dissolution behaviors of ThO2(cr) and PuO2(cr) in synthetic groundwater were investigated at room temperature (23  2°C) under atmospheric conditions. The synthetic groundwater was prepared according to the chemical composition of the KURT-DB3 groundwater. The pH and Eh of the synthetic groundwater were pH 8.9 and 0.5 V, respectively, and the major components were Na, K, Ca, Mg, Si, Cl, SO4, F and HCO3 ions. A few mg of ThO2(cr) and PuO2(cr) powder were added in the synthetic groundwater and the concentrations of Th and Pu in supernatant were monitored for 5 months of reaction time. The concentrations of Th before and after ultracentrifugation were compared, while the solid-liquid phase separation of Pu samples could not be applied due to the small volume of sample solutions. The concentrations of Th and Pu were measured by ICP-MS and alpha spectrometry, respectively. Geochemist’s Work Bench (GWB, standard, 17.0) was applied for the modeling with ThermoChimie TDB v. 11a, which was updated with the latest NEA-TDB (vol. 14). Aqueous species distributions and solubility limiting solid phases of Th and Pu under the synthetic groundwater conditions were evaluated. The results of geochemical modeling indicate that aqueous Th-OH-CO3 ternary species and Pu(IV) species are dominant in solutions equilibrated with ThO2(s) and PuO2(am, hyd), respectively. The dissolution behaviors of ThO2(cr) and PuO2(cr) are comparable to the dissolution of ThO2(aged, logKsp = 8.5) and the oxidative dissolution of PuO2(am, hyd) in the presence of PuO2(coll, hyd), respectively.

Targeting Microcystin (MC), which is most abundantly detected in the North-Han River water area, we analyzed the relationship between the MC biosynthesis gene (mcyA gene), cyanobacteria cell density, and MC concentration, derived an RNA-MC conversion formula, and derived the cyanobacteria. The concentration of MC present in cells was predicted. In the North-Han River waters, the mcyA gene was found mainly at downstream sites of the North-Han River after Muk-Hyeon Stream junction, and higher copy numbers were found on average than other sites. In the Uiam Lake waters upstream of the North-Han River, the mcyA gene copy number increased at the Kong-Ji Stream point, and after September, the mcyA gene copy number decreased throughout the North-Han River waters. The expression of the mcyA gene was concentrated in the short period of summer due to the spatio-temporal difference between upstream and downstream water bodies. The mcyA gene expression level was not only highly correlated with MC concentration, but also correlated with the cell density of Microcystis aeruginosa and Dolichospermum circinale, which are known to biosynthesize MC. Six conversion formulas derived based on the RNA-MC relationship showed statistical significance (p<0.05) and exhibited high correlation coefficients (r) of 0.9 or higher. The expression level of MC biosynthesis gene present in eRNA determines the synthesis of cyanotoxin substances in water, quickly quantifies gene activity, and can be fully utilized for early warning of MC development.

유기 전구체와 금속 이온, 또는 금속-옥소 클로스터 간의 규칙적 배열을 통한 종의 다양성을 장점으로 하는 금속- 유기 골격체(Metal-Organic Frameworks, MOFs)는 에너지 사용량이 높은 상변화 기반 분리공정을 대체할 수 있는 에너지 효율 적인 막 기반 분리 기술의 개발 가능성을 열어주었다. 이에 최근 10년 동안 다결정 MOFs 분리막 합성 기술에서 상당한 진전 이 있었지만, 매우 제한된 종류의 MOFs만이 활용되고 있다. 이러한 기술 개발의 정체는 다결정 분리막의 비 선택적인 확산 경로인 결정 사이 결함(intercrystalline defects)에 대한 명확한 해결법이 없기 때문이다. 후처리 성능 제어기술(postsynthetic modifications, PSMs)은 기존 분리막을 플랫폼으로 활용하고 이를 물리적 그리고/혹은 화학적으로 처리함을 통해 분리 특성 을 개선 혹은 변경하는 기술을 말한다. PSMs 기술은 특정 분리막을 개발하는 데 있어서 새로운 MOFs를 설계하거나 막 합성 기술을 개발하지 않아도 된다는 장점이 있어서 다결정 MOF 분리막의 다양성을 제공하기 위한 새로 부상하는 전략으로 평가 된다. 본 총설에서는 PSMs 기술을 7개의 세부기술((1) 공유결합법, (2) 결정간 결함 플러깅법, (3) 결정 내부 결함 치유법, (4) 기공내 기능성 소재 함침법, (5) 기공 경화법, (6) 전구체 치환법 및 (7) 비정질화법)로 분류하고, 각 세부기술의 연구 동향 및 도전과제 그리고 향후 연구 방향에 대해 논의하고자 한다.

Antioxidants are food additives that extend the shelf life of food products by preventing lipid rancidity caused by active oxygen. They can either be naturally-derived or manufactured synthetically via chemical synthesis. In this study, method validation of five synthetic antioxidants, namely butylated hydroxyanisole, butylated hydroxytoluene, tertiary butylhydroquinone, propyl gallate, and disodium ethylenediaminetetraacetic acid, was performed using a high performance liquid chromatography–ultraviolet visible detector, and the method applicability was evaluated by analyzing foods containing antioxidants. The coefficient of determination (R2) average was 0.9997, while the limit of detection and limit of quantification were 0.02–0.53 and 0.07–1.61 mg/kg, respectively. The intra and inter-day accuracies and precisions were 83.2±0.7%–98.7±2.1% and 0.1%–5.7% RSD, respectively. Inter-laboratory validation for accuracy and precision was conducted using the Food Analysis Performance Assessment Scheme quality control material. The results satisfied the guidelines presented by the AOAC International. In addition, the expanded uncertainty was less than 16%, as recommended by CODEX. Consequently, to enhance public health safety, the results of this study can be used as basis data for evaluating the intake of synthetic antioxidants and assessing their risks in Korea.

Anderson-type polyoxometalate (POM) with general formula of [Hy(XO6)M6O18]n- (y=0-6, n=2-8, M=addenda atom, X=heteroatom) represents one of the basic topological structures among POM-type family. Anderson-type POMs have a planar arrangement and two terminal oxygen atoms attached to each addenda metal atom unlike other type. Thus, the Anderson-type POMs have high reactivity and various coordination modes. The various multifunctional organic-inorganic hybrid materials can be synthesized using the Anderson-type POMs as an inorganic building block. Another important feature of the Anderson-type POMs is the incorporation of the heteroatoms with various sizes and oxidation states, which can lead to tune chemical properties. No Anderson-type POMs with early transition metal ions in the heteroatom site have been reported previously. Recently, we reported the synthesis of titanium-containing Anderson-type POM, Na2K6Ti0.92W6.08O24∙12H2O (Ti-POM), which consists of pure inorganic framework built from a central Ti atom surrounded by six WO6 inorganic scaffold. Herein, in-depth studies were conducted to find optimal synthesis conditions such as composition and pH. The success of synthesis was confirmed with Powder X-ray Diffraction that the Ti-POM has a rhombohedral structure with space group of R-3m (No. 166) when the TiOSO4·xH2SO4∙yH2O/ Na2WO4∙2H2O molar ratio is in the range of 0.07 to 0.33. But outside of this range, other unwanted phases coexist. In a basic condition (pH=12), a single-phase Ti-POM with good crystallinity can be obtained, while a Keggin-type POM, NaxK10-x(H2W12O42), was formed through the decomposition of Ti-POM at pH lower than 7.