• Journal of Magnetics
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• v.21 no.1
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• pp.46-50
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• 2016

$Fe_2O_3/TiO_2$ nanocomposite were successfully synthesized by co-precipitation method using $Fe(NO_3)_3{\cdot}9H_2O$ and $Ti(SO_4)_2$ as raw materials. Structural and textural features of the mixed oxide samples were characterized by X-ray diffractometer, field emission scanning electron microscopy and energy-dispersive X-ray. The effects of initial concentration of oxytetracycline (OTC), different competitive ions and organics on the photocatalytic degradation rate of OTC by the $Fe_2O_3/TiO_2$ nanocomposite were analyzed under UV and visible light irradiation. The results indicate that the optimized initial concentration of OTC was 50 mg/L to achieve the best photocatalytic efficiency. $Cu^{2+}$, $NH_4{^+}$, $C_3H_8O$ and EDTA in the aqueous suspension were found to suppress the degradation rate of OTC, whereas the effect of $NO_3{^-}$ and $H_2C_2O_4$ can be ignored.

• Journal of the Korean Chemical Society
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• v.24 no.1
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• pp.53-62
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• 1980

The present work is concerned with the studies on the production of PZT ceramics by newly developed mixing process, which tentatively named "precipitation mixing method", consists of precipitating lead carbontate in the presence of $TiO_2$ and/or $ZrO_2$. Mixtures of $PbCO_3$ and $TiO_2$ or $ZrO_2$ were compared with those obtained by ball-milling with special emphasis on the rate and mechanism of formation of lead titanate and lead zirconate. A possiblity for obtaining PZT ceramics by "precipitation mixing method" was established.

• Journal of Sensor Science and Technology
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• v.17 no.5
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• pp.361-368
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• 2008

Nanosized $SnO_2$ particles were synthesized by homogeneous precipitation method using tin chloride ($SnCl_4{\cdot}5H_{2}O$) and urea ($CO(NH_2)_2$). The powders were heated at $500^{\circ}C$ and $600^{\circ}C$ for 2h. The crystal structure, microstructure, thermal behavior, specific surface area were analyzed using XRD, FE-SEM, TGA and BET, respectively. The initial resistance and the $H_2$ sensing properties were measured as a function of ${Sb_2}{O_3}$ and Pd doping concentrations. The resistance was decreased with the addition of ${Sb_2}{O_3}$ and the sensitivity for $H_2$ gas was increased with the addition of Pd. Thus, the optimum $H_2$ gas sensing property was obtained in the 0.25.mol% ${Sb_2}{O_3}$ and 1.w% added $SnO_2$ powders.

• Journal of the Korean Electrochemical Society
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• v.10 no.1
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• pp.48-51
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• 2007

In order to investigate the effects of particle size and specific surface area(BET area) of spinel powder, $LiMn_2O_4$ were synthesized using metal oxide precursor by co-precipitation method(CoP) and solid state reaction (SSR) .X-ray diffraction(XRD) patterns revealed that the both prepared powder has a well developed spinel structure with Fd3m space group. The $LiMn_2O_4$ prepared by co-precipitation showed spherical morphology with narrow size distribution. However, the $LiMn_2O_4$ prepared by solid state reaction showed relatively smaller particles with irregular shape. The measured BET areas of the powers are $0.8m^2g^{-1}$ (CoP) and $3.6m^2g^{-1}$(SSR). The electrochemical performance of the Prepared $LiMn_2O_4$ powders was evaluated using coin type cells(CR2032) at elevated temperature ($55^{\circ}C$). The $LiMn_2O_4$ prepared by co-precipitation showed the better cycling performance(82.3%capacity retention at $50^{th}$ cycle) than that of the $LiMn_2O_4$(68.3%) prepared by solid state reaction at elevated temperature.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.115-116
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• 2023

This study aims to investigate and improve the carbon dioxide sequestration capability and the mechanical properties of non-hydraulic low calcium silicate cement especially designed for CO₂ reaction and ordinary Portland cement subjected to the carbonation curing facilitating pH swing method. Nitric acid (HNO₃) was utilized as an liquid for the mixing of cement paste to enhance the initial dissolution of Ca ions from the cements by promoting low pH environment and prevent the direct precipitation of Ca with the anion, owing to the high solubility of Ca(NO₃)₂ in water. The results presented that the higher the concentration of HNO₃, the higher the compressive strength and CO₂ sequestration (until 0.1 M). Ca dissolution caused by the harsh acid attack onto the anhydrous cement particle lead to the higher carbonation reaction degree, forming abundant CaCO₃ crystals after the reaction. However, cement paste mixed with excessively high concentration of HNO₃ presented deterioration due to the too harsh pH environment and abundant NO₃- ions which are known to retard the reaction of cement.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2000.11a
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• pp.290-293
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• 2000

After kaolin clay was compulsorily contaminated with Co$^{2+}$ion, the remediation characteristics by electrokinetic method were analyzed. Ethanoic buffer was injected in the soil column and $CH_3$COOH was continuously inputted in cathode reservoir to restrain the pH elevation. Since pH of the cathode side of the soil column was 4.0 at initial and was restrained by 6.5 at 43.6 hours, Precipitation, Co(OH)$_2$, was not formed in the column. Effluent rate increased with time passage and remediation in the column in initial time was mainly controlled by ion migration. 13.1% of total in the soil column was remediated in 10 hours, and the 6.8% of total in 20.8 hours, and the 71.7% of total in 43.6 hours, and the 94.6% of total in 43.6 hours. Meanwhile, the residual concentrations in the column calculated by the developed model were similar to those by experiment.t.

• Journal of the Korean Chemical Society
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• v.58 no.1
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• pp.100-104
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• 2014

Magnetite nanoparticles were prepared by co-precipitation method and then silica was coated onto the surface of $Fe_3O_4$ by hydrolysis of TEOS. The silica coated magnetite nanoparticles were characterized for its structural, microstructural, optical, vibrational and magnetic properties by X-ray diffraction analysis, Scanning electron microscopy, UV-visible spectroscopy, Infrared spectroscopy and Vibration sample magnetometer, respectively. XRD study confirmed the presence of $SiO_2$ on the surface of magnetite nanoparticles. SEM study indicated that with increase in TEOS content the particles become bigger and mono-disperse. It was also found that the silica coating prevents magnetic particles from aggregation and imparts excellent stability.

• Clean Technology
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• v.24 no.1
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• pp.35-40
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• 2018

$Co_3O_4$ catalysts for $N_2O$ decomposition were prepared by co-precipitation method. Ce and Zr were added during the preparation of the catalyst as promoter with the molar ratio (Ce or Zr) / Co = 0.05. Also, 1 wt% $K_2CO_3$ was doped to the prepared catalyst with impregnation method to investigate the effect of K on the catalyst performance. The prepared catalysts were characterized with SEM, BET, XRD, XPS and $H_2-TPR$. The $Co_3O_4$ catalyst exhibited a spinel crystal phase, and the addition of the promoter increased the specific surface area and reduced the particle and crystal size. It was confirmed that the doping of K improves the catalytic activity by increasing the concentration of $Co^{2+}$ in the catalyst which is an active site for catalytic reaction. The catalytic activity tests were carried out at a GHSV of $45,000h^{-1}$ and a temperature range of $250{\sim}375^{\circ}C$. The K-impregnated $Co_3O_4$ catalyst showed much higher activity than $Co_3O_4$ catalysts with promoter only. It is found that the K-impregnation increased the concentration of $Co^{2+}$ more than the added of promoter did, and lowered the reduction temperature to a great extent.

• Geomechanics and Engineering
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• v.20 no.2
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• pp.165-174
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• 2020

The enzyme-induced carbonate precipitation (EICP) method has been investigated to improve the hydro-mechanical properties of natural soil deposits. This study was conducted to explore the stiffness evolution during various stress scenarios. First, the optimal concentration of urea, CaCl₂, and urease for the maximum efficiency of calcite precipitation was identified. The results show that the optimal recipe is 0.5 g/L and 0.9 g/L of urease for 0.5 M CaCl₂ and 1 M CaCl₂ solutions with a urea-CaCl₂ molar ratio of 1.5. The shear stiffness of EICP-treated sands remains constant up to debonding stresses, and further loading induces the reduction of S-wave velocity. It was also found that the debonding stress at which stiffness loss occurs depends on the void ratio, not on cementation solution. Repeated loading-unloading deteriorates the bonding quality, thereby reducing the debonding stress. Scanning electron microscopy and X-ray images reveal that higher concentrations of CaCl₂ solution facilitate heterogeneous nucleation to form larger CaCO₃ nodules and 11-12 % of CaCO₃ forms at the interparticle contact as the main contributor to the evolution of shear stiffness.

• Korean Chemical Engineering Research
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• v.56 no.3
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• pp.381-387
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• 2018

Our study focuses on upgrading real biogas obtained under Indian scenario using carbon capture and utilization (CCU) technology to remove carbon dioxide ($CO_2$) and utilize it by forming metal carbonate. Amines such as monoethanolamine (MEA), diethanolamine (DEA), and sodium hydroxide (NaOH) were used to rapidly convert gaseous $CO_2$ to aqueous $CO_2$, and $BaCl_2$ was used as an additive to react with the aqueous $CO_2$ and rapidly precipitating the aqueous $CO_2$. All experiments were conducted at $25^{\circ}C$ and 1 atm. We analyzed the characteristics of the $BaCO_3$ precipitates using X-ray diffractometry (XRD), scanning electron microscopy - Energy dispersive spectroscopy (SEM-EDS) and Fourier-transform infrared spectroscopy (FT-IR) analyses. The precipitates exhibited witherite morphology confirmed by the XRD results, and FT-IR confirmed that the metal salt formed was $BaCO_3$, and EDS showed that there were no traces of impurities present in it. The quantity of the $BaCO_3$ was larger when formed with DEA. Also, a comparison was done with a previous study of ours conducted in Korean conditions. Finally, we observed that the carbonate obtained using real biogas showed similar properties to carbonates available in the market. An economic analysis was done to show the cost effectiveness of the method employed by us.