• Proceedings of the Korean Environmental Health Society Conference
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• 2005.11a
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• pp.143-146
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• 2005

O_$3/H_2O_2$를 이용하여 1,4-dioxane의 산화처리에 미치는 $H_2O_2$ 농도의 영향에 대하여 고찰하였다. 또한 1,4-dioxane의 생물학적 분해가능성도 파악하였다. 실험은 bubble column reactor를 이용하여 수행되었으며, 여러 pH 및 $H_2O_2$ 조건에서 수행되었다. $H_2O_2$ 농도가 40 - 120 mg/L 범위에서, 초기 $H_2O_2$ 농도가 높을수록 1,4-dioxane의 제거율 및 생물분해성도 증가하였다.

• Journal of the Korean Chemical Society
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• v.67 no.5
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• pp.333-338
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• 2023

In this study, the H₂O reaction with SiO clusters was investigated using ab initio Monte Carlo simulations and density functional theory calculations. Three chemistry models, PBE1/DGDZVP (Model 1), PBE1/DGDZVP (Si atom), and aug-cc-pVDZ (O and H atoms), (Model 2) and PBE1/aug-cc-pVDZ (Model 3), were used. The average bond lengths, as well as the relative and reaction energies, were calculated using Models 1, 2, and 3. The average bond lengths of Si-O and O-H are 1.67-1.75 Å and 0.96-0.97 Å, respectively, using Models 1, 2, and 3. The most stable structures were formed by the H transfer from an H₂O molecule except for Si₃O₃-H₂O-1 cluster. The Si₃O₃ cluster with H₂O exhibited the lowest reaction energy. In addition, the Bader charge distributions of the Si_nO_n and (SiO)_n-H₂O clusters with n = 1-7 were calculated using Model 1. We determined that the reaction sites between H₂O and the SiO clusters possessed the highest fraction of electrons.

• Journal of the Korean Chemical Society
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• v.59 no.2
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• pp.117-124
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• 2015

The DFT and ab initio calculations have been performed to elucidate hydrogen interaction of hydrogen polyoxide dimers, $H_2O_n-H_2O_m$ (n=1-4, m=1-4). The optimized geometries, harmonic vibrational frequencies, and binding energies are predicted at various levels of theory. The harmonic vibrational frequencies of the molecules considered in this study show all real numbers implying true minima. The higher-order correlation effect were discussed to compare MP2 result with CCSD(T) single point energy. The binding energies were corrected for the zero-point vibrational energy (ZPVE) and basis set superposition errors (BSSE). The largest binding energy predicted at the CCSD(T)/cc-pVTZ level of theory is 8.18 kcal/mol for $H_2O_4-H_2O_3$ and the binding energy of water dimer is predicted to be 3.00 kcal/mol.

• The Journal of Korean Medicine
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• v.22 no.3
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• pp.21-30
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• 2001

목적 : 이전 연구에서 단삼 추출액이 강력한 항산화 작용이 있음을 확인한 바 있어 단삼 추출액이 신장세뇨관 세포에서 oxidant에 의한 세포사망 및 DNA 손상을 방지하는 지를 조사하고 이러한 효과가 지질의 과산화를 억제하는 효과에 기인하는 지를 시험하였다. 방법 : 신장 근위세뇨관 세포 유래 세포주인 opossum kidney (OK)세포를 이용하여 세포 사망은 frypan blue exclusion방법을 이용하여 평가하였고, DNA손상 정도는 double stranded DNA의 파괴를 측정하여 평가하였다. Oxidant 약물 모델로는 $H_2O_2$를 사용하였다. 결과 : $H_2O_2$는 적용시 간과 농도에 비례하여 세포 사망을 유도하였다. 단삼 추출액은 0.05% 농도에서 $H_2O_2$에 의한 세포사망 및 DNA 손상을 방지하였다. 이러한 방지효과는 $H_2O_2$ 제거 효소인 catalase와 철 착염제인 deferoxamine에 의해서도 나타났다. 그러나 강력한 항산화제인 DPPD는 $H_2O_2$에 의한 세포 사망이나 DNA손상을 방지하지 못하였다. $H_2O_2$는 세포내 ATP 농도를 감소시켰으며. 이러한 감소는 poly (ADP-ribose) polymerase억제제인 3-aminobenzamide에 의해 방지되었으나 단삼 추출액에 의해서는 영향을 받지 않았다. 3-aminobenzamide는 $H_2O_2$에 의한 세포 사망을 방지하였다. $H_2O_2$는 지질의 과산화를 증가시켰으며, 이러한 변화는 단삼 추출액과 DPPD에 의해 방지되었다 결론 : OK 세포에서 $H_2O_2$에 의한 세포사망과 DNA 손상에는 지질의 과산화가 중요한 역할을 하지 않으며, 단삼 추출액의 $H_2O_2$에 의한 세포 사망과 DNA 손상 방지 효과는 항산화 작용이 아닌 다른 기전에 기인하는 것으로 사료된다.

• Clean Technology
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• v.14 no.1
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• pp.40-46
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• 2008

The dehumidifiers were prepared by the impregnation of the zeolites such as MCM 48, USY, beta on the silica ceramic paper. Their capacities for $H_2O$ absorption and regeneration of the bed were tested in a fixed bed reactor system. The $H_2O$ absorption capacities of the dehumidifiers impregnated with the zeolites were $1.5{\sim}2$ times higher than those without the zeolites. Especially, the humidifier using MCM 48 and colloidal silica showed an excellent capacity (42.1g $H_2O/g$ absorbent). It was found that the $H_2O$ absorption capacities of the dehumidifiers were improved because the amount of silica gel, the main component in absorbing $H_2O$, increased due to the large surface area and pore volume of the zeolites. In addition, $H_2O$ was easily desorbed from the dehumidifiers with zeolites at $80^{\circ}C$ of regeneration temperature and the desorption amount of $H_2O$ was the same as that absorbed. It was confirmed that the $H_2O$ absorption capacities of the dehumidifiers impregnated with zeolite were maintained without deactivation through the repeated cyclic experiments.

• Journal of the Korean Chemical Society
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• v.43 no.6
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• pp.628-635
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• 1999

Direct preparative method of 2,6-diformyl-p-cresol and 2-hydroxy-3-hydroxy-5-methylbenzaldehyde from 2,6-bis(hydroxymethyl)-4-methylphenol using activated $Mn(IV)O_2$ was described. Hexadentate compartmental Iigands, $H_4L[A]\;and\; H_4L[B]$ were prepared by condensation reactions of 2-hydroxy-3-hydroxy methyl-5-methylbenzaldehyde with ethylenediamine and 1,3-diaminopropane respectively. By the reaction of macrocycle($H_4[20]DOTA$) with Ln(III) nitrate {Ln(III)=Pr, Sm, Cd, Dy }, discrete mononuclear Ln(III) complexes of the type $[Ln(H_2[20]DOTA)(ClO_4)(H_2O)]\;{\cdot}\;3H_2O$ were synthesized in the solid state. $[Ln([20]DOTA)(NO_3)(H_2O)](NO_3)_2\;{\cdot}\;xH_2O$ was placed in methanol for 2 days, and $[Ln([20]DOTA)(NO_3)(CH_3OH)]^{2+}$ was formed. The equilibrium constants(K) for the substitution of coordinated $CH_3OH$ in the Ln-[20]DOTA complexes by various auxiliary ligand, $L_a$(=salicylic acid, p-chlorobenzoic acid, benzoic acid, acetic acid, 4-bromophenol) were determined spectroscopically at 25$^{\circ}C$ and 0.1M $NaClO_4$. The K values calculated were in the order of salicylic acid > p-chlorobenzoic acid > benzoic acid > acetic acid > 4-bromophenol, while pKa of auxiliary ligands was in the opposite trend.

• Bulletin of the Korean Chemical Society
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• v.32 no.3
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• pp.988-992
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• 2011

$CO_2$ adsorption on mineral sorbents has a potential to sequester $CO_2$. This study used a density functional theory (DFT) study of $CO_2$ adsorption on barium oxide (BaO) in the presence of $H_2O$ to determine the role of $H_2O$ on the $CO_2$ adsorption properties on the ($2{\times}2$; $11.05\;{\AA}{\times}11.05\;{\AA}$) BaO (100) surface because BaO shows a high reactivity for $CO_2$ adsorption and the gas mixture of power plants generally contains $CO_2$ and $H_2O$. We investigated the adsorption properties (e.g., adsorption energies and geometries) of a single $CO_2$ molecule, a single $H_2O$ molecule on the surface to achieve molecular structures and molecular reaction mechanisms. In order to evaluate the coordinative effect of $H_2O$ molecules, this study also carried out the adsorption of a pair of $H_2O$ molecules, which was strongly bounded to neighboring (-1.91 eV) oxygen sites and distant sites (-1.86 eV), and two molecules ($CO_2$ and $H_2O$), which were also firmly bounded to neighboring sites (-2.32 eV) and distant sites (-2.23 eV). The quantum mechanical calculations show that $H_2O$ molecule does not influence on the chemisorption of $CO_2$ on the BaO surface, producing a stable carbonate due to the strong interaction between the $CO_2$ molecule and the BaO surface, resulting from the high charge transfer (-0.76 e).

• Journal of Environmental Health Sciences
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• v.31 no.5 s.86
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• pp.404-410
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• 2005

The pH efforts on the removal of 1,4-dioxane and the biodegradobility enhancement of dioxane contaminated water were investigated using $O_3/H_2O_2$ baled advanced oxidation process. Experiments were conducted using a bubble column reactor under different initial pH. The $O_3/H_2O_2$ process effectively converted 1,4-dioxane to more biodegradable intermediates which had a maximum $BOD_5$ enhancement at pH 11 within the experimental range, precisely, when the initial pH increased, $BOD_5$ enhanced. However, in case of removal efficiencies of 1,4-dioxane during $O_3/H_2O_2$ oxidation the optimum condition was shown at pH 9 compared with pH 6 and 11. TOC and COD values were not largely changed for all reaction time. From the results of 1,4-dioxane removal efficiency, TOC, COD, and $BOD_5$ enhancement with reaction time, it was surely observed that 1,4-dioxane was just converted to biodegradable materials, not completely oxidized to carbon dioxide.

• Journal of the Korean Chemical Society
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• v.51 no.3
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• pp.240-243
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• 2007

The eight coordinated yttrium(III) complex Y(tpb)3(H2O)2 (Htpb=4,4,4-Trifluoro-1-phenyl-1,3-butanedione) has been synthesized and structurally characterized by X-ray diffraction method. The coordination polyhedron of Y(tpb)3(H2O)2 has a dodecahedron. The angle between two trapezia, Y-O2-O1-O5-O6 and Y-O4-O3-O8-O7, is 89.59°. The O1-O5 and O3-O8 distances are 2.965 and 2.995 A whereas the O2-O6 and O4-O7 distances are 4.256 and 4.403 A.

• Transactions on Electrical and Electronic Materials
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• v.6 no.1
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• pp.29-32
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• 2005

Chemical mechanical polishing is an essential process in the production of copper-based chips. On this work, the stability of hydrogen peroxide ($H_{2}O_{2}$) as an oxidizer of copper CMP slurry has been investigated. $H_{2}O_{2}$ is known as the most common oxidizer in copper CMP slurry. But $H_{2}O_{2}$ is so unstable that its stabilization is needed using as an oxidizer. As adding KOH as a pH buffering agent, stability of $H_{2}O_{2}$ decreased. However, $H_{2}O_{2}$ stability in slurry went up with putting in small amount of BTA as a film forming agent. There was no difference of $H_{2}O_{2}$ stability between pH buffering agents KOH and TMAH at similar pH value. Addition of $H_{2}O_{2}$ in slurry in advance of bead milling led to better stability than adding after bead milling. Adding phosphoric acid resulted in the higher stability. Using alumina C as an abrasive was good at stabilizing for $H_{2}O_{2}$.