• Korean Chemical Engineering Research
• /
• v.52 no.4
• /
• pp.436-442
• /
• 2014

In this study, we developed an optical-fiber sensor using cobalt chloride solution to monitor temperature in real-time between long distance points unaffected by the electro-magnetic wave and the vibration. Cobalt chloride solutions were made using 10% water and 90% ethanol (v/v) solution. The transmittance of these solutions was analyzed on 655 nm using UV-Visible spectrometer regarding temperature change. Also 30.8 mM cobalt chloride solution was gelled by dissolving polyvinyl butyral and the transmittance of this was analyzed on 655 nm regarding temperature change. The results of transmittance and optical power measurement showed decrease of both transmittance and optical power with increase of temperature from 66.8% and 149.5 nW at $25^{\circ}C$ to 7.1% and 48 nW at $70^{\circ}C$, respectively. These results support the possibility of gelled cobalt chloride/polyvinyl butyral as an optical-fiber sensor to monitor temperature change.

• Journal of the Korean Chemical Society
• /
• v.40 no.5
• /
• pp.302-307
• /
• 1996

Diethanolamine dithiocarbamate is known to react with dichlorobis(ethylenediamine)cohalt(Ⅲ) chloride to form [Co(dtc)3](dtc=diethanolamine dithiocarbamate) in which two sulfur atoms of the dithiocarbamate are bound to cobalt. The complex is moderately soluble in acetone, but sparingly soluble in carbon disulfide. Kinetics and mechanisms of the reaction of dichlorobis(ethylenediamine)cobalt(Ⅲ) chloride with diethanolamine dithiocarbamate have been studied in aqueous solution. Activation parameters have been calculated from the kinetic data for the reaction and from these results a possible mechanism for the reaction has been proposed.

• Journal of the Korean Applied Science and Technology
• /
• v.30 no.2
• /
• pp.233-243
• /
• 2013

The inorganic pearlescent pigment have high physical and chemical stability, thus it is used in a variety field, which has better light stability, solvent resistance and thermostability. In this paper, we were synthesized the pearlescent pigment for cosmetics which was coated cobalt chloride for base of blue color metal oxide on mica titania substrate using hydrothermal synthesis method. To complement the color of the pigment by cobalt, pearl pigment were coated by different metal salt and cobalt ratio, to implement a variety of color value, depending on the kind of metal salts were synthesized. Synthesized pearlescent pigments appear various color as kind of added metal salt precursor and molar ration of cobalt and other metals. We controlled coating and color by composition of metal salt and type of metal salts, and that confirm the pigment characteristics of color changes through the analysis of color difference meter. Synthesized pigment was characterized by SPM, SEM, XRD, and EDS.

• Journal of the Korean Chemical Society
• /
• v.51 no.6
• /
• pp.479-486
• /
• 2007

Bicarbonate 완충용액에서 Co-RDE를 이용하여 RDE 회전속도와 완충용액 속의 염화이온이 Co의 부식과 부동화에 미치는 영향을 연구하였다. Co-RDE의 회전속도가 부식에 미치는 영향은 Levich 식과 일치하였으며 부동화 막을 파괴하는데 염화이온의 효과가 큼을 알 수 있었다. 혼합 전위 이론을 사용하여 대류확산 조건에서 회전속도의 증가에 따라 부식전위가 양의 방향으로 증가하는 모형을 발견하였다. Tafel 영역에서 Co의 용해반응과 수소가 발생하는 환원반응은 전하이동과 물질이동을 이용하여 설명할 수 있었다.

• Journal of the Korean Chemical Society
• /
• v.19 no.1
• /
• pp.53-64
• /
• 1975

The polymerization of methyl methacrylate initiated by cobalt(II) chloride in tetrahydrofuran has been studied. The conversion was increased liearly with polymerization time at initial stage of 6${\sim}$7% conversion and then the rate of polymerization was slightly reduced, and after that the autoacceleration was observed. The rate of polymerization was increased with the concentration of cobalt(Ⅱ) chloride, but at the concentration of cobalt(II) chloride higher than $3.4{\times}10^{-4}$ mole/l the rate of polymerization was decreased. The rate of polymerization was dependent on the 1.38 power of the concentration of methyl methacrylate. The effect of the radical inhibitor DPPH was observed and the inhibition time was increased with the concentration of DPPH. The apparent overall activation energy was calculated to be 13.2 kcal/mole. In the copolymerization of methyl methacrylate ($M_1$) and styrene ($M_2$), the monomer reactivity ratio was found to be $r_1$ = 2.35, $r_2$ = 0.78. From the above results. the initiation mechanism of polymerization was discussed and it was considered that the polymerization proceeds mainly via diradical mechaism.

• Korean Chemical Engineering Research
• /
• v.46 no.4
• /
• pp.769-776
• /
• 2008

The stereoselective synthesis of chiral terminal epoxide is of immense interest due to their utility as versatile starting materials as well as chiral intermediates. In this study, new chiral Co(salen) complexes bearing cobalt(II) chloride, iron(III) chloride and zinc(II) nitrate have been synthesized and characterized. The mass and EXAFS spectra provided the direct evidence of formation of complex. Their catalytic activity and selectivity have been demonstrated for the asymmetric ring opening of terminal epoxides such as styrene oxide and phenylglycidylether by hydrolytic kinetic resolution technology and for the synthesis of glycidyl buthylate. The easily prepared complexes exhibited very high enantioselectivity for the asymmetric ring opening of epoxides with $H_2O$ nucleophile, providing enantiomerically enriched terminal epoxides (>99% ee). The newly synthesized chiral salen showed remakablely enhanced reactivity with substantially low loadings. The system described in this work is very efficient for the sinthesis of chiral epoxide and 1,2-diol intermediates.

• Resources Recycling
• /
• v.26 no.1
• /
• pp.22-29
• /
• 2017

When the ambient air pressure was $0.1kg/cm^2$, there were few spherically formed droplets, which showed very badly fragmented state. The average particle size of the particles constituting the droplet was about 40 nm. When the air pressure increased to $0.5kg/cm^2$, the ratio of the spherical droplet forms increased, but still showed a state of severe disruption. The average particle size of the particles was reduced to about 35 nm. As the air pressure increased to $3kg/cm^2$, the ratio of spherical droplet form significantly increased, the degree of fragmentation even further decreased and the average particle size decreased to 30 nm. When the air pressure increased from 0.1 to $1kg/cm^2$, the XRD peak intensity showed little change, but the specific surface area was decreased. As the air pressure increased to $3kg/cm^2$, the intensity of XRD peaks showed a little decrease, while the specific surface area increased.

• Resources Recycling
• /
• v.25 no.6
• /
• pp.41-49
• /
• 2016

The present study was intended to prepare cobalt oxide ($Co_3O_4$) powder of average particle size 50 nm or less by spray pyrolysis reaction using the raw cobalt chloride ($CoCl_2$) solution, in order to identify the change in the nature of the particles according to the change in the nozzle tip size. When the nozzle tip was 1 mm, it turned out that most of the droplets were spherical and the surface showed very tight structure. The average particle size of the finally formed particles was 20-30 nm. When the nozzle tip size was 2 mm, some of the droplets formed were spherical, but a considerable part of them showed severely disrupted form. particles formed showed an average particle size of 30 - 40 nm. For the nozzle tip size of 5 mm, spherical droplets were almost non-existent and most were in badly fragmented state. The tightness of surface structure of the droplets has greatly been reduced compared with other nozzle tip sizes. Average size of the formed particles was about 25 nm. As the nozzle tip size increased from 1 mm to 2 mm and 3 mm, the intensities of the XRD peaks have changed little, but significantly been reduced when the nozzle tip size increased to 5mm. As the nozzle tip size increased from 1 mm to 2 mm, the specific surface area of the particles decreased, but the nozzle tip size increased to 5mm, the specific surface area remarkably increased.

• Korean Journal of Metals and Materials
• /
• v.46 no.4
• /
• pp.227-232
• /
• 2008

Solvent extraction reaction of cobalt by Alamine336 from strong hydrochloric acid solution was identified by analyzing the solvent extraction data reported in the literature. Analysis of the data by graphical method revealed that Alamine336 took part in the solvent extraction reaction as a monomer in the concentration ranges, [Co(II)] : 0.0169 - 0.102 M, [Alamine336] ; 0.02- 1.75 M, and [HCl ] : 5 - 10 M. The following solvent extraction reaction and equilibrium constant was obtained from the experimental data by considering the activity coefficients of chemical species present in the aqueous phase. $Co^{2+}+2Cl^{-}+R_3NHCl_{org}=CoCl_3\;R_3NH_{org}$, $K_{ex}=2.21$ The distribution coefficients of cobalt predicted in this study agreed well with those reported in the literature.

• The Journal of the Convergence on Culture Technology
• /
• v.9 no.3
• /
• pp.587-592
• /
• 2023

Cobalt oxide (Co₃O₄·CoO) ultra fine particles were synthesized by liquid phase precursor method. cobalt(II) chloride hexahydrate (CoCl₂·6H₂O) was as a starting material. A plant-derived crystalline cellulose was used as impregnating materials. A impregnated precursor was calcined at a temperature of 350 to 900℃ to obtain cobalt oxide particles having a particle size of 1 to 10㎛. The crystallization process and morphology according to the calcination temperature were examined, and the properties of the synthesized powder were evaluated using SEM and XRD. It was confirmed that a crystal phase of Co₃O₄ began to form around 350℃ and crystal growth occurred up to 900℃. At a temperature above 500℃, the Co₃O₄ crystal was changed to another crystal phase CoO.