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Comparative compressional behavior of Zeolite-W with different extra-framework cations
Hyeonsu Kim,Pyosang Kim,Donghoon Seoung,Yongmoon Lee 대한지질학회 2021 대한지질학회 학술대회 Vol.2021 No.10
Zeolite, one of microporous materials, has been widely studied for industrial application such as catalysts or adsorbent due to its size- and shape-selective property. Many experiments of zeolites have addressed the physio-chemical properties in ambient and non-ambient condition. High-pressure researches have been carried out in the last decades and shedded a new sights into phase stability and elastic behavior in response to adopting pressure and pressure-transmitting media (PTM). Zeolite-W is one of small pore zeolites and synthetic phase which has same framework with natural zeolite, Merlinoite (MER, (K,Na)5Ca,Ba)₂Al9Si23O64·23H₂O). We have prepared several extra-framework cation, EFC, analogues (K<SUP>+</SUP>: K-MER, Na<SUP>+</SUP>: Na-MER, Ag<SUP>+</SUP>: Ag-MER, NH₄<SUP>+</SUP>: NH₄-MER) of Zeolite-W by synthesis and cation-exchange method. Chemical composition of prepared samples was confirmed from Energy dispersive X-ray spectroscopy and Thermal Gravimetric Analysis. Compressional behavior of monovalent cation forms up to 5.22 GPa at room temperature is investigated by synchrotron X ray powder diffraction at 3D and 5A beamlines. We use a diamond-anvil cell as a pressurizing tool and water as PTM. In all cases, unit cell constants slightly increase in wet condition and then gradually decrease by pressure without phase transition. Calculated bulk modulus is 37(3) GPa, 38(4) GPa, 49(2) GPa, 47(3) GPa in order of Na-MER, Ag-MER, K-MER, NH4-MER, and it reveals that (in)compressibility is related to extra-framework cation size. Further understanding in atomic scale, Rietveld refinement is ongoing.
Kim Jun Hyeong,Kim Hyeonsu,Kim Woo Youn 대한화학회 2022 Bulletin of the Korean Chemical Society Vol.43 No.5
Deep learning (DL) can be a useful approach to molecular applications such as the organic light-emitting diode (OLED) development via high-throughput virtual screening. Various representations have been proposed to incorporate molecular structures in DL methods. However, it is yet to be clear which one would be better for accurate prediction of molecular electronic properties. Here, we carried out a comparative study on the performance of four widely used molecular representations to elucidate an optimal solution for DL applications to OLED materials. We implemented six DL models based on the four representations and assessed their accuracies in the prediction of the electronic properties of thermally activated delayed fluorescence (TADF) molecules. The attention gated graph neural network based on molecular graphs showed the highest accuracy for test sets and TADF candidates. Therefore, the molecular graph can be used as an optimal representation to predict the TADF-related molecular properties.
정현수(Hyeonsu Jeong),장영희(Younghee Jang),이예환(Ye Hwan Lee),김준오(Jun Oh Kim),최승원(Seungwon Choi),변성제(Seongje Byun),김재헌(Jaeheon Kim),김정현(Junghyun Kim),이상문(Sang Moon Lee),김성수(Sung Su Kim) 유기성자원학회 2022 유기성자원학회 학술발표대회논문집 Vol.2022 No.추계
비소는 반도체, 착색체 등을 만드는데 있어 비소가 꼭 필요한 원료 중 하나이기 때문에 높은위험성에도 불구하고 지속적으로 사용되고 있다. 비소는 유리공장, 농약제조시설 등에서 배출이 되어지며, 이는 자연스럽게 자연과 인간에게 노출되고 있다. 특히 먹는 물로 취급되는 지하수에도 광산등에서 용출된 비소가 포함되어 인간에게 만성적인 질병을 일으키는 독성 중금속으로 알려져 있다. 이러한 비소를 제거하기 위해 활성탄, 음이온 교환, 역삼투 방법등을 이용한다. 그 중 흡착법은 다양한 가스상 오염물질 제거 기술 중 운전비가 저렴하며 대부분의 물질 저감이 가능하다. 특히 잔류 독성 물질이 포함되어 있는 수처리 분야에서 비용을 저감할 수 있는 해결책으로써 제시되고 있다. 본연구에서는 TiO2의 황산처리를 통해 두가지의 sulfated-TiO2를 제조하여 비소 흡착 성능을 확인하였다. 제조된 흡착제는 다양한 분석을 통해 물리화학적 특성을 확인하였고, 흡착제 표면의 황산종과비소는 SO4 2-그룹에 의해 결합됨을 확인하였다. 특히, 전자 밀도를 조절하여 TiO2의 표면 산성도를조절하고, 비소의 흡착 성능을 증진시킬 수 있는 흡착소재 제조 방법을 최적화하였다. 이를 통해 개발된 흡착제로 기존 비소 흡착제 대비 20% 이상 성능 증진된 소재를 제안한다.