• Journal of the Korean Chemical Society
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• v.63 no.2
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• pp.94-101
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• 2019

Nb, Mo-doped and Nb/Mo-codoped $VO_2(M)$ nanocrystallites with various doping levels were synthesized for the first time by a hydrothermal and post thermal transformation method. The reversible phase transition characteristics of those doped $VO_2(M)$ was comparatively investigated. Nb-doping of $VO_2(M)$ by this method resulted in a very efficient lowering of the transition temperature ($T_c$) with a rate of $-16.7^{\circ}C/at.%$ that is comparable to W-doping, while Mo-doping did not give a serious reduction of $T_c$ with only a rate of $-5.1^{\circ}C/at.%$. Nb/Mo-codoping gave a similar result to Nb-doping without a noticeable difference. The thin films of Nb-doped and Nb/Mo-codoped $VO_2(M)$ with a thickness of ca. 120 nm were prepared by a wet-coating of the nanoparticle-dispersed solutions. Those films showed a good thermochromic modulation of near infrared radiation with 30-35% for Nb-doped $VO_2(M)$ and 37-40% for Nb/Mo-codoped ones. Nb/Mo-codoped $VO_2(M)$ film showed slightly enhanced thermochromic performance compared with Nb-doped $VO_2(M)$ film.

• Ceramist
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• v.21 no.3
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• pp.283-292
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• 2018

Here, we introduce various type of inorganic nanostructure synthesized with functional nanoparticles and silica. From two decades ago, functional inorganic nanoparticles have been synthesized and highlighted, now we moved to next level of wet-chemical synthesis. By integrating functional nanoparticles with silica, we were able to synthesize multi-functional nanostructure, which expand the applications of nanoparticles to catalyst, drug carrier, sensors. In this context, silica has been spotlighted due to its versatility. Silica has highly biocompatible, relatively transparent and stable under harsh conditions. Thus it can be used as good supporter to synthesize complex multi-functional nanostructure when mixed with other functional nanoparticles. A various shape of complex nanostructures have been synthesized including core-shell type, yolk-shell type and janus type etc. In this paper, we have described the purposes of synthesizing silica noncomplex and various case studies for biomedical applications and self-assembly.

• Applied Chemistry for Engineering
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• v.31 no.3
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• pp.317-322
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• 2020

Hydroxylammonium nitrate (HAN; NH₃OHNO₃) is an ionic energy material having a low melting temperature and vapor pressure with a high oxygen balance. To utilize it as an oxidizer for a high content liquid mono-propellant, a dual solvent was used to obtain HAN in a solid particulate form. The dehydrated crystal from an aqueous HAN was washed with dual organic solvents including acetone and ethanol, finally resulting in the moisture content of 13.8 wt%. When acetone was applied as a single solvent, the maximum synthesis yield of 88%, the HAN content evaluated by TGA of 86.2%, and the decomposition temperature ranged 160℃ to 205℃ were achieved.

• Applied Chemistry for Engineering
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• v.25 no.4
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• pp.425-429
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• 2014

Pd on charcoal particles were prepared by wet impregnation to develop commercial catalyst for aerobic benzyl alcohol oxidation. Especially, one of room temperature ionic liquids, [Hmim][$PF_6$], was used as an effective solvent in the synthesis to improve the metal dispersion of the catalysts. Among the Pd/Charcoal with various Pd concentrations, 7.5 wt% catalyst showed the higher catalytic activity and stability. Moreover, Ag was used as a promoter with various ratios in catalyst preparation. Under identical reaction conditions, the catalyst with 9 : 1 of Pd and Ag weight ratios was most active due to higher metal dispersion.

• Clean Technology
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• v.19 no.4
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• pp.446-452
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• 2013

In this paper, the wet mixing method was introduced to prepare spinel lithium manganese oxide (LMO) with $Li_2CO_3$ and $MnCO_3$. The physical properties of the resulting lithium manganese oxide were characterized by the XRD and SEM. The adsorption properties of LMO for $Li^+$ were investigated by batch methods. The maximum adsorption capacity of lithium was calculated from Langmuir isotherm and found to be 27.25 mg/g. The LMO are found to have a remarkable lithium ion-sieve property with distribution coefficients ($K_d$) in the order of $Ca^{2+}$ < $K^+$ < $Na^+$ < $Mg^{2+}$ < $Li^+$, which is promising in the lithium extraction from seawater.

• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2281-2284
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• 2014

Polystyrene beads (PS beads) with narrow size distribution were synthesized, and their diameter was controlled from 1.2 to $5{\mu}m$ by varying the injection rate of a styrene solution containing initiator and the concentration of reactant, such as initiator and capping material. The diameter of the PS beads increased with increasing in the injection rates and the initiator concentration or decreasing the capping material concentration. Then, we used the PS beads as building block, and organized them into a hexagonally close-packed monolayer on substrate with template-assisted manual assembly. We showed perfect hexagonally close-packed organization of the PS beads with various sizes in large-scale area. And we demonstrated the superiority of the dry manual assembly over the wet self-assembly in terms of simplicity, speed, perfect ordering, and large scale.

• Applied Chemistry for Engineering
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• v.33 no.3
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• pp.258-271
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• 2022

Ferrate (VI) [Fe(VI)] has multi-functional features, which include potential oxidant, coagulant, and disinfectant. Because of these distinctive properties, numerous studies on the synthesis of ferrate (VI) and its possible applications in a wide research areas have been investigated. This review highlights the recent development made on different synthesis methods for ferrate including wet chemical, electrochemical, and thermal methods. The recent advancements achieved in ferrate (VI) oxidation and the synergistic effect of the oxidative properties of ferrate (VI) in the presence of various compounds or materials are also included. Moreover, this review discusses the applications of ferrate (VI) for degrading various types of water pollutants and its reaction mechanism. The optimized experimental conditions and interaction mechanisms of ferrate (VI) with micro-pollutants, dyes, and other organic compounds are also elaborated upon to provide greater insight for future studies. Lastly, the limitations and prospects of the ferrate use in the treatment of polluted water are described.

• Journal of Environmental Science International
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• v.16 no.12
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• pp.1431-1437
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• 2007

Cobalt titanates($CoTiO_x$), such as $CoTiO_3$ and $Co_2TiO_4$, have been synthesized via a solid-state reaction and characterized using X-ray diffraction(XRD) and X-ray photoelectron spectroscopic(XPS) measurement techniques, prior to being used for continuous wet trichloroethylene(TCE) oxidation at $36^{\circ}C$, to support our earlier chemical structure model for Co species in 5 wt% $CoO_x/TiO_2$(fresh) and(spent) catalysts. Each XRD pattern for the synthesized $CoTiO_3$ and $Co_2TiO_4$ was very close to those obtained from the respective standard XRD data files. The two $CoTiO_x$ samples gave Co 2p XPS spectra consisting of very strong main peaks for Co $2p_{3/2}$ and $2p_{1/2}$ with corresponding satellite structures at higher binding energies. The Co $2p_{3/2}$ main structure appeared at 781.3 eV for the $CoTiO_3$, and it was indicated at 781.1 eV with the $Co_2TiO_4$. Not only could these binding energy values be very similar to that exhibited for the 5 wt% $CoO_x/TiO_2$(fresh), but the spin-orbit splitting(${\Delta}E$) had also no noticeable difference between the cobalt titanates and a sample of the fresh catalyst. Neither of all the $CoTiO_x$ samples were active for the wet TCE oxidation, as expected, but a sample of pure $Co_3O_4$ had a good activity for this reaction. The earlier proposed model for the surface $CoO_x$ species existing with the fresh and spent catalysts is very consistent with the XPS characterization and activity measurements for the cobalt titanates.

• Clean Technology
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• v.11 no.2
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• pp.83-90
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• 2005

This paper is about a new method of synthesis organic tanning agent (polymer, polyphenol, polyresin) and discusses their tanning property. It was found that properties of the leather manufactured with application of organic tanning agent were similar to those applied with conventional chrome tanning agent and reducing effects of Cr, T-N, COD, SS concentrations in the effluent.

• Journal of the Korean Chemical Society
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• v.44 no.6
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• pp.592-599
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• 2000

The fine particles of binary ceramic composite of titania-partially-stabilized zirconia(TPSZ) were synthesized by ultrasonic spray pyrolysis at the various temperatures, compositions and concentrations and the effects of process factors for synthesis on the characteristics of fine particles were discussed. The starting salt solutions were prepared to have the ionic concentrations of 0.025~0.1 M aqueous solutions. The fine particles were prepared to have the compositions of 90~97.5 wt% of $ZrO_2$ and 2.5~10 wt% of $TiO_2$. The temperatures for particle synthesis were regulated to be 400~550$^{\circ}C$ as a drying zone, 800~1100$^{\circ}C$ as a pyrolysis zone. The produced fine particles were collected by a wet process and analyzed to investigate characteristic properties after being dried. The compositions of ceramic fine particles were determined by Inductively Coupled Plasma-Atomic Emission Spectroscopy(ICP-AES) technique and phases, morphologies and particle sizes of those were investigated by Raman Spectroscopy, X-ray diffraction(XRD), Scanning Electron Microscopy(SEM), Transmission Electron Microscopy(TEM) and Particle Size Analyzer(PSA) techniques.