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Spectroscopic observation of H2 migration in structure-I clathrate hydrate
이흔,Sukjeong Choi,Kyuchul Shin,Jong-Ho Cha 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.6
We demonstrate the spectroscopic observation of H2 migration in the binary structure-I (sI) clathrate hydrate. The H2 molecules captured into sI small cage (sI-S) at lower temperature migrate to sI large cage (sI-L) through shared pentagonal face of 51262 cage. The hexagonal faces of 51262 cage provide the windows essential for creating continuous diffusion paths for H2 molecules. It is essential to realize that the vacant channels formed by the linkage of specific cages can play an important role in guest diffusion pathways and occupancy occurring in a complex clathrate hydrate matrix.
이흔,Sukjeong Choi,김기섭,연순화,Jong-Ho Cha,김창진,Ick-Dong Yoo 한국화학공학회 2007 Korean Journal of Chemical Engineering Vol.24 No.5
nanoparticles exhibiting antimicrobial properties via self-regulated reduction were successfully pre-pared by using hydroxylated ionic liquids in an aqueous phase without additives. A new water-phase synthesis of silvernanoparticles using 1-(2-hydroxyethyl)-3-methylimidazolium tetrafluoroborate ([HEMIm][BF4]) and 1-(2'-hydroxy-ethyl)-2-methyl-3-dodecylimidazolium chloride ([C12HEMIm][Cl]) was described. 1-(2-hydroxyethyl)-3-methylimi-dazolium tetrafluoroborate serves as both a reductant and a stabilizer in this fabrication. Furthermore, we presented theantimicrobial properties of the resulting silver nanoparticles through the minimal inhibitory concentrations (MIC) test.
Removal of carbon residue precursor in waste plastic pyrolysis oil via oxidation
Jeon Sukjeong,Lee Jaehong,Kim Seong Cheon,Kang Jin-Hyuk,Lee Dongho,Byon Hye Ryung,Park Jeasung,Choi Siyoung Q. 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.11
A novel method to remove the carbon residue precursor from waste plastic pyrolysis oil has been developed to improve subsequent pyrolysis oil refining efficiency by reducing fouling. The carbon residue content of the pyrolysis oil that cannot be filtered is reduced by precipitating the carbon residue precursor from the pyrolysis oil under mild conditions. By emulsifying an aqueous solution of oxidant and the pyrolysis oil, the carbon residue precursor was oxidized at the oil-water interface without oxidizing the pyrolysis oil. Enhancing intermolecular interaction by hydrophilic functional groups formed by oxidation induces the precipitation of carbon residue precursors. The precursor removal was determined by the type and reaction time of oxidants. FeCl3 and H2O2 are efficient oxidants, and recycling those oxidant solutions can also remove the carbon residue precursor. The number of recycles with the precursor removal effect was determined by the amount of oxidant remaining in the aqueous solution. Also, a short 15-minute FeCl3 reaction can eliminate the precursor. Reducing the reaction time is expected to increase process efficiency, as unnecessary oxidation and energy consumption are decreased. Our research suggests the pretreatment of the pyrolysis oil to reduce the carbon residue content, thereby reducing the fouling during the subsequent pyrolysis oil refining.
Discrete Magnetic Patterns of Nonionic and Ionic Clathrate Hydrates
Shin, Kyuchul,Cha, Minjun,Choi, Sukjeong,Dho, Joonghoe,Lee, Huen American Chemical Society 2008 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.130 No.51
<P>In this communication, the charge transfer phenomenon from ionic host lattice to nonionic guest molecule was observed by magnetization and Raman spectroscopy measurements for nonionic and ionic clathrate hydrates. The present findings on the magnetic property of nonionic guest molecules in ionic hydrate might provide important information on the unrevealed nature of host-guest interaction in ionic hydrate systems. The charge transfer occurring between ionic host and nonionic guest molecules will open up interesting application fields for ionized hydrate complexes and activated secondary guest molecules.</P>
연순화,이흔,박제성,박영준,Sukjeong Choi,Kyuchul Shin,Jiwoong Seol,차민준 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.1
Clathrate compounds are crystalline materials formed by a physical interaction between host and relativelylight guest molecules. Various types of nano-sized cages surrounded by host frameworks exist in the highly uniquecrystalline structures and free guest molecules are entrapped in an open host-guest network. Recently, we reported twopeculiar phenomena, swaping and tuning, naturally occurringuest molecules, must be the chalengeable material in the sense of physics and moreover possesses versatile appli-cations in the field of superconductivity technology and thermonuclear industry. In this regard, we attempted for thefirst time to synthesize helium hydrates at moderate temperature and pressure conditions. According to inclusion phe-nomena, helium itself normally cannot form clathrate hydrates due to being too small molecularly without the helpof hydrate former molecules (sI, sII, and sH formers). In this study, the hydrate equilibria of the binary clathrate hydrate% . Direct volumetric measure-ments were also carried out to confirm the exact amount of helium captured in the hydrate cages. Finally, the crys-talline structure of the formed mixed hydrates was identified by powder X-ray difraction, resulting in structure II.