• Korean Chemical Engineering Research
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• v.50 no.5
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• pp.795-801
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• 2012

Nanoparticles have received significant attention because of their unusual characteristics including high surface area to volume ratios. Thiol ligand have been used as stabilizers of metal nanoparticles since Brust et al. They reported the preparation method of ligand capped metal nanoparticles by protecting the nanoparticles with a self-assembled monolayer of dodecanethiolate. In this method, volatile organic compounds (VOCs) were used as sovents. This study was carried out to replace these VOCs with room temperature ionic liquids (RTILs). We used two type of ILs to prepare metal nanoparticles. One is a hydrophobic IL, [BMIM][[$PF_6$] (1-Butyl-3-methylimidazolium hexafluorophosphate) purchased from IL maker, C-Tri from Korea and the other one is a hydrophilic one, [BMIM][Cl] (1-Buthy-3-methylimdazolium chloride) sinthesized by us. In the case of preparing Ag and Au nanoparticles using [BMIM][Cl], we didn't use phase transition reagents and ethanol because it has hydrophilic property and preparing Au, Ag nanoparticles using [BMIM][[$PF_6$] the method is as same as Brust et al.'s except using [BMIM][[$PF_6$] instead of organic solvent because it has hydrophobic property. FT-IR and UV-vis, TEM, TGA analysis have been used in an attempt to determine the particle size and verify functional groups. The particle size obtained from TEM was very similar to those obtained by Brust et al. This is a clear example of ligand capped metal nanoparticles prepared using ionic liquids. And the experimental result demonstrated ionic liquids can act as a highly effective medium for the preparation and stabilization of gold and silver metal nanoparticles.

• Clean Technology
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• v.12 no.3
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• pp.128-137
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• 2006

The volume change of an ionic liquid and the phase separation behavior of room temperature ionic liquid(RTIL)/organic compound mixture in supercritical carbon dioxide were measured in a high pressure view cell. 1-Butyl-3-methylimidazolium hexafluorophosphate ([bmim][$PF_6$]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][$BF_4$]) was used as ionic liquid(IL). and methanol and dimethyl carbonate were used as organic compound. For a fixed amount of [bmim][$PF_6$] the lower critical endpoint (LCEP) pressure, where the liquid phase is split, decreased as increasing the amount of organic compound. The LCEP pressure became higher as the water content of ionic liquid was higher. However, for water contents above a certain value, no LCEP was formed. LCEP appeared 1.0 MPa higher for a mixture with [bmim][$BF_4$] than with [bmim][$PF_6$]. There was almost no difference in the K-point pressures for different types of ionic liquid and for different amounts of organic liquid. When the concentration of ionic liquid([bmim][$PF_6$]) (IL/(IL+MeOH)) in the initial liquid mixture was larger than 5.9 mol% at the LCEP of the mixture, the volume of $L_1$ because larger than the volume of $L_2$. When it was smaller, however, the volume became smaller, too. The volume change of ionic liquid in the presence of carbon dioxide decreased as increasing the temperature, while it increased as increasing the pressure. For temperatures between 313.15 to 343.15K at 300 bar, it was about 123~125 % of the original volume.

• Bulletin of the Korean Chemical Society
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• v.33 no.7
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• pp.2295-2298
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• 2012

We describe herein a three-dimensionally diverse micropatterning of poly(lactic acid), as a biopolymer, using 1-butyl-3-methylimidazolium-based room-temperature ionic liquids (bmim-based RTILs), [bmim]X (X = $SbF_6$, $PF_6$, $NTf_2$, Cl). Utilizing the hydrophobic bmim-based RTILs, [bmim]X (X = $SbF_6$, $PF_6$, $NTf_2$) and a phase separation technique, we were able to produce white and opaque membranes with a three-dimensional structure closely packed with particles ($10-50{\mu}m$ in diameter). The particlulate structure, made by the assistance of [bmim]$NTf_2$ and DCM, interestingly transformed to a fibrous structure by using a cosolvent, e.g., DCM/$CF_3CH_2OH$. When we used an increased amount of [bmim]$NTf_2$, the particles were effectively detached and macrosized ($100-500{\mu}m$ in diameter) and the oval-shaped beads were obtained in a powder form. By varying the counter-anion type of the imidazolium-based RTIL, for example from $NTf_2^-$ to $Cl^-$, the particulate 3D-morphology was once more transformed to a porous structure. These reserch results could be potentially useful, as a method to fabricate particulate scaffolds, fibrous or porous scaffolds, and beads as a biopolymer device in diverse fields including drug delivery, tissue regeneration, and biomedical engineering.

• Advances in nano research
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• v.10 no.3
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• pp.295-312
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• 2021

A new ionic liquid functionalized magnetic silica nanoparticle was synthesized and characterized and tested as an adsorbent. The adsorbent was used for magnetic solid phase extraction on ICP-MS method. Simultaneous determination of precious metal Au has been addressed. The method is simple and fast and has been applied to standard water and surface water analysis. A new method for separation/analysis of trace precious metal Au by Magnetron Solid Phase Extraction (MSPE) combined with ICP-MS. The element to be tested is rapidly adsorbed on CoFe2O4@SiO2@[BMIM]PF6 composite nano-adsorbent and eluted with thiourea. The method has a preconcentration factor of 9.5-fold. This method has been successfully applied to the determination of gold in actual water samples. Hydrophobic Ionic Liquids (ILs) 1-butyl-3-methylimidazole hexafluorophosphate ([BMIM]PF6) coated CoFe2O4@SiO2 nanoparticles with core-shell structure to prepare magnetic solid phase extraction agent (CoFe2O4@SiO2@ILs) and establish a new method of MSPE coupled with inductively coupled plasma mass spectrometry for separation/analysis of trace gold. The results showed that trace gold was adsorbed rapidly by CoFe2O4@SiO2@[BMIM]PF6 and eluanted by thiourea. Under the optimal conditions, preconcentration factor of the proposed method was 9.5-fold. The linear range, detection limit, correlation coefficient (R) and relative standard deviation (RSD) were found to be 0.01~1000.00 ng·mL-1, 0.001 ng·mL-1, 0.9990 and 3.4% (n = 11, c = 4.5 ng·mL-1). The CoFe2O4@SiO2 nanoparticles could be used repeatedly for 8 times. This proposed method has been successfully applied to the determination of trace gold in water samples.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.117-117
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• 2015

Availability of X-ray photoelectron spectroscopy (XPS) for the identification of ionic liquids (ILs) was tested. Commercially available ionic liquids (1-butyl-3-methyl imidazolium tetrafluoroborate ([BMIM] $BF_4$), (1-butyl-3-methyl imidazolium trifluoromethanesulfonate ([BMIM] OTf), (1-butyl-3-methyl imidazolium hexafluorophosphate ([BMIM] $PF_6$), 1-hexyl-3-imidazolium hexafluorophosphate ([HMIM] $PF_6$), and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM] $Tf_2N$) were qualitatively and semi-quantitatively analyzed with XPS. In order to confirm whether the results of XPS were correct, conventional method such as a nuclear magnetic resonance (NMR) was performed. After the XPS results were convinced by NMR, we synthesized ILs (1-(4-sulfonic acid) butyl-3-butylimidazolium trifluoromethanesulfonate ([SBBIM] OTf), 1-(4-sulfonic acid) propyl-3-methylimidazolium trifluoromethanesulfonate ([SPMIM] OTf), and 1-(4-sulfonic acid) propyl-3-butylimidazolium trifluoromethanesulfonate ([SPBIM] OTf) and analyzed it with XPS and NMR as well. It was successful the usage of XPS to analyze ILs without any purification processes.

• Korean Chemical Engineering Research
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• v.45 no.3
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• pp.286-290
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• 2007

The esterification efficiency of several ionic liquids has been investigated to determine the feasibility for the conversion of free fatty acids to alkylester. Five ionic liquid catalysts having strong acidity, BPC[$AlCl_3$], BMIM[$Bf_4$], BMIM[$Pf_6$], EMIM[$Ntf_2$], BMIM[Otf], have been employed in this work. BPC[$AlCl_3$] has the highest esterification efficiency among the ionic liquid catalysts. Over 90% conversion efficiency has been achieved in the esterification of the simulated used cooking oil by BPC[$AlCl_3$] with two hours reaction time. Since BPC[$AlCl_3$] has several advantages such as high esterification activity, ease of separation from reaction mixture and reusability after treatment procedure, it will be a promising catalyst for the conversion of free fatty acids to esters in waste fats.

• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1628-1632
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• 2010

Porous ${\eta}-Al_2O_3$ was synthesized by modified sol-gel method using ionic liquid as a templating material. The addition of ionic liquid assisted to increase the surface area of alumina. However, the acidity of aluminas prepared with ionic liquids was hardly affected regardless the change of its structural properties. Among the ionic liquids used in this study, 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][$PF_6$]) was the most effective ionic liquid to produce porous ${\eta}-Al_2O_3$ particles. The catalytic performance of these aluminas has been investigated in dehydration of methanol to produce dimethyl ether. The alumina prepared with [Bmim][$PF_6$] outperformed the other aluminas except ${\eta}-Al_2O_3$ without modification in this reaction.

• Membrane Journal
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• v.22 no.4
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• pp.280-283
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• 2012

The study is aiming to prepare supported ionic liquid membranes for carbon dioxide separation efficiently. The ionic liquid, [bmim][${PF_6}^-$] (1-butyl-3-methyl-imidazolium hexafluorophosphate) was fixed in the pores of PVDF micro-filtration membrane with a nominal pore size 0.1 ${\mu}m$. The permeabilities of $N_2$, $H_2$ and $CO_2$ gases through the prepared ionic liquid membrane were 0.075, 0.203 and 1.380 GPU, respectively. The selectivities of $CO_2/N_2$, $H_2/N_2$ were 14.2 and 2.69, respectively. Also, the supported ionic liquid membrane could be operated stably up to 2.0 bar with the immobilization of ionic liquid in the pores.

• Clean Technology
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• v.14 no.4
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• pp.248-255
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• 2008

The volume expansion of three ionic liquids (ILs) in the presence of supercritical carbon dioxide has been measured at pressures up to 32 MPa and at temperatures from 313.15 to 333.15 K in a high-pressure view cell. The imidazolium-derivative ionic liquids 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][$PF_6$]), 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][$BF_4$]), and 1-octyl-3-methylimidazolium tetrafluoroborate ([omim][$BF_4$]) were employed in this research. The effects of pressure, temperature, nature of anion and cation as well as the water content on the volume expansion of ILs by absorbing $CO_2$ were investigated experimentally. The volume expansion was higher for the ILs with longer cationic alkyl group and for the ILs with lower anion polarity. The lower the water content, the lower the temperature, or the higher the pressure, the higher was the expansion of IL phase.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.1
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• pp.99-102
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• 2005

Organic solvents are widely used in biotransformation systems. There are many efforts to reduce the consumption of organic solvents because of their toxicity to the environment and human health. In recent years, several groups have started to explore novel organic solvents called room temperature ionic liquids in order to substitute conventional organic solvents. In this work, lipase-catalyzed transesterification in several uni- and bi-phasic systems was studied. Two representative hydrophobic ionic liquids based on 1-butyl-3-methylimidazolum coupled with hexafluorophosphate ([BMIM][$PF_6$]) and bis[{trifluoromethylsulfonyl} imide] ([BMIM] [$Tf_{2}N$]) were employed as reaction media for the transesterification of n-butanol. The commercial lipase, Novozym 435, was used for the transesterification reaction with vinyl acetate as an acyl donor. The conversion yield was increased around $10\%$ in a water/[BMIM][$Tf_{2}N$] bi-phasic system compared with that in a water/hexane system. A higher distribution of substrates into the water phase is believed to enhance the conversion yield in a water/[BMIM][$Tf_{2}N$] system. Partition coefficients of the substrates in the water/[BMIM][$Tf_{2}N$] bi-phasic system were higher than three times that found in the water/hexane system, while n-butyl acetate showed a similar distribution in both systems. Thus, RTILs appear to be a promising substitute of organic solvents in some biotransformation systems.