• Bulletin of the Korean Chemical Society
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• v.9 no.5
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• pp.317-322
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• 1988

Premicellar precipitation, resolubilization and luminescing behaviors of $RuL_3^{2+}$ (L = bpy, phen, $Me_2bpy$) in aqueous alkylsulfate and sulfonate solutions were studied. Addition of the anionic surfactants to $RuL_3\;^{2+}$ solutions caused initial precipitation which was redissolved by further addition of the surfactants. The apparent solubility products $K_{sp}$'s of the precipitates were evaluated assuming 1:2 salt formation. The values were smaller as the ligand is more hydrophobic and the length of hydrocarbon chain of the surfactant is longer. The $K_{sp}$ values for L = bpy were constant over wide surfactant concentration range. However, those for L = $Me_2bpy$ and also for phen, but to less extent, increased with the surfactant concentration. The resolubilization of 1:2 salts was followed by red-shift of emission band and extensive emission quenching above critical concentration of the surfactants. The critical concentration was lower for more hydrophobic surfactant. For L = $Me_2bpy$, the blue-shifted emission band with enhanced emission intensity was observed in intermediate surfactant concentration region. The high ionic strength of media prevented the precipitate formation, but facilitated the red-shift of the emission bands. The results support that the precipitate is dissolved by accretion of surfactant anions to the salts to form water-soluble surfactant-rich $RuL_3$-surfactant anionic species. These species appeared to aggregate cooperatively to produce large clusters which exhibited the red-shifted emission.

• Membrane and Water Treatment
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• v.13 no.4
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• pp.183-189
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• 2022

This study seeks towards an optimal way to control sulfate ions in semiconductor wastewater effluent with potential eco-toxicity. We developed a system based on ettringite (Ca₆Al₂(SO₄)₃(OH)₁₂·26H₂O). The basic idea is that the pH of the water is raised to approximately 12 with Ca(OH)₂. After, aluminium salt is added, leading to the precipitation of ettringite. Lab-scale batch and continuous experiment results with real semiconductor wastewater demonstrated that 1.5 and 1 of stoichiometric quantities for Ca²⁺ and A³⁺ with pH above 12.7 could be considered as the optimal operation condition with 15% of sludge recycle to the influent. A mixed AlCl₃ + Fe reagent was selected as the beneficial Al³⁺ source in ettringite process, which resulted in 80% of sludge volume reduction and improved sludge dewaterability. The results of continuous experiment showed that with precipitation as ettringite, sulfate concentration can be stably reduced to less than 50 mg/L in effluent from the influent 2,050 ± 175 mg/L on average (1,705 ~ 2,633 mg/L).

• Applied Chemistry for Engineering
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• v.19 no.6
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• pp.690-692
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• 2008

Pure glycerol could be obtained from a biodiesel byproduct by separation processes including neutralization, precipitation, and distillation. The contents of distilled glycerol through the above separation processes were measured and the results were compared according to experimental conditions such as acid concentration and precipitation temperature. Neutralization processes were carried out in the concentration range of 5~37 wt% hydrochloric acid, 5~95 wt% sulfuric acid, and 5~85 wt% phosphoric acid, respectively. Precipitation temperatures in neutralization were controlled in the range of 293~333 K. Higher values of the distilled glycerol content were obtained due to the salt removal in the pretreatment case of neutralization with 10 wt% sulfuric acid and precipitation of 313 K with 85 wt% phosphoric acid, respectively. The variations of acid concentration and precipitation temperature in pretreatment steps affected to some extent glycerol recovery from the biodiesel byproduct.

• Journal of Electrochemical Science and Technology
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• v.14 no.1
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• pp.75-84
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• 2023

The accumulation of spent carbide (YG8), not only pollutes the environment but also causes waste of tungsten, cobalt and other rare metal resources. To better address this issue, we proposed a combined electrochemical separation process of low-temperature aqueous solution and high-temperature molten salt for tungsten and cobalt. H₂WO₄ was obtained from spent carbide in an aqueous solution, and we calcined it to obtain WO₃, which was used as a raw material to obtain tungsten by using molten salt electrodeposition. The influence of the current efficiency and the electrochemical behavior of the discharge precipitation of W(VI) were also studied. The calcination results showed that the morphology of WO₃ was regular and there were no other impurities. The maximum current efficiency of 82.91% was achieved in a series of electrodeposition experiments. According to XRD and SEM analysis, the recovered product was high purity tungsten, which belongs to the simple cubic crystal system. In the W(VI) reduction mechanism experiments, the electrochemical process of W(VI) in NaCl-Na₂WO₄-WO₃ molten salt was investigated using linear scanning voltammetry (LSV) and chronoamperometry in a three-electrode system. The LSV showed that W(VI) was reduced at the cathode in two steps and the electrode reaction was controlled by diffusion. The fitting results of chronoamperometry showed that the nucleation mechanism of W(VI) was an instantaneous nucleation mode, and the diffusion coefficient was 7.379×10^-10 cm²·s^-1.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.379-382
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• 2006

In this study, an attempt was made to form magnesium oxide layer via aqueous solution route of salt precipitation process. A layer with flake morphology was formed from the process and various dopants were added during the forming process. The films formed were characterized using SEM, XRD, and cathodoluminescence measurement. In addition, the discharge characteristics were evaluated using panel tests. The results indicate that MgO film can be formed via the aqueous solution process successfully, of which characteristics are comparable to those of MgO film formed by e-beam evaporation process.

• Journal of the Korean Ceramic Society
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• v.25 no.1
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• pp.54-58
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• 1988

In order to depress PbO vaporization during calcination and improve sinterability in low temperature, a method for preparing homogeous Lead-Zirconate-Titanate (PZT) powder from aqueous salt solution by precipitation is described. In this method, single phae PZT fine powders are formed at above 500$^{\circ}C$. PZT-ceramics using these powders have high sinterability, and good sintering characteristics relatively low temp. (-high apparent density, low porosity, low water adsorption etc.)

• Journal of Korean Society of Environmental Engineers
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• v.31 no.7
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• pp.505-514
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• 2009

Aqueous potassium salt of serine was proposed as an alternative $CO_2$ absorbent to monoethanolamine (MEA) and its $CO_2$ absorption characteristics were studied. The experiment has been conducted using screening test equipment with NDIR type gas analyzer and vapor-liquid equilibrium apparatus. $CO_2$ absorption/desorption rate and net amount of $CO_2$ absorbed in cyclic process are the criteria to assess the $CO_2$ absorption characteristics in this study. Effective $CO_2$ loading of potassium salt of serine and MEA are 0.425 and 0.230 respectively. Cyclic capacities are 0.354 and 0.298 for potassium salt of serine and MEA. The absorption rate of the potassium serinate decreased sharply at $CO_2$ loading is 0.1 and were maintained approximately at half of MEA. To enhance the absorption rate of aqueous potassium salt of serine, small quantities of rate promoters, namely piperazine and tetraethylenepentamine were blended, so that rich $CO_2$ loading were increased by 13.7% and 18.7% respectively. The rich $CO_2$ loading of potassium salt of serine was 29.2% and 35.0% higher than those of aqueous sodium and lithium salt of serine, respectively. The absorption rate of potassium salt of valine and isoleucine which have similar molecular structures to serine were lower than that of serine because of the presence of bulky side group. Precipitation phenomena during $CO_2$ absorption were discussed by the aid of literatures.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.2
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• pp.92-98
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• 2012

The co-precipitation technique has been applied to synthesize biphasic calcium phosphate (BCP). $Ca(NO_3)_2{\cdot}4H_2O$, $(NH_4)_2HPO_4$, TEOS and $Mg(NO_3)_2{\cdot}6H_2O$ as the starting materials was used. After the heat treatment of powder crystalline phases HAp and ${\beta}$-TCP analysis showed a mixed phase. The overall spectra appear to have mainly two modes corresponding to characteristic $PO^{3-}_4$ and $OH^-$ groups. After immersion in Hanks' Balanced Salt Solution (HBSS) for 1 week a precipitation started to be formed with individual small granules on the specimen surface. An MTT assay indicated that ionic substituted BCP powders had no cytotoxic effects on MG-63 cells, and that they have good biocompatibility.

• Korean Journal of Veterinary Research
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• v.5 no.1
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• pp.1-16
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• 1965

I. A Comparison of Sodium Sulfate Precipitation and Zone(Paper, Agar) Electrophoresis; Many kinds of techniques have been used for fractionating serum proteins. In the present study, using bovine serum, the fractions obtained with sodium sulfate were compared with those determined by zone electrophoresis. 1. Fibrinogen was precipitated with 4 to 10 percent of sodium sulfate. 2. ${\gamma}$-globulin required 10 to 16 percent of the salt for precipitation. 3. ${\beta}$-globulin began to precipitate at 12 percent sodium sulfate, and completed precipitation at approximately 26 percent in paper electrophoresis, while at 22 percent in agar electrophoresis. 4. ${\alpha}$-globulin completed precipitation at 13 to 28 percent sodium sulfate in paper electrophoresis and at 22 percent in agar electrophoresis. 5. Albumin began to precipitate at 14 percent of the salt, and was free from the mixture of globulins approximately at 28 percent in paper electrophoresis, while at 22 percent in agar electrophoresis. The results of comparing fractions by the two methods were as follows: 1. Euglobulin (15%) was equal to the sum of the most ${\gamma}$-globulin and a small quantity of the ${\alpha}$-, and ${\beta}$-globulins. 2. Pseudoglobulin I (15-17.5%) corresponded to the most ${\alpha}$-, ${\beta}$-globulins and a small quantity of albumin. 3. Pseudoglobulin II(18-22%) was a mixture of the ${\alpha}$-, ${\beta}$-globulins and albumin fraction. 4. Albumin (above 22%) contained the most albumin fraction separated by zone electrophoresis and a small quantity of the ${\alpha}$-, and ${\beta}$-globulins. As mentioned above the fractions obtained with sodium sulfate were a mixture of the various proportion of the fractions determined by zone electrophoresis. The solubility of serum fractions to sodium sulfate coincided with the mobility of those by zone electrophoresis. (By percent of sodium sulfate we mean gram of sodium sulfate contained in $100m{\ell}$ of solution). II. Immunological Studies on Serum Protein Fractions with Sodium Sulfate; In the previous report the fractions of bovine serum protein with sodium sulfate compared with those obtained by zone electrophoresis, and the findings were that the former contained various proportion components of the latter. In this study the author studied whether or not the fractions with sodium sulfate are simple component antigenically by immunoelectrophoresis and micro double diffusion test (Immuno-precipitation), using rabbit antiserum to bovine serum. In immunoelectrophoresis, normal bovine serum developed with rabbit antibovine serum showed about ten distinct precipitin arcs. The distribution of these arcs was as follows: 1 albumin, 2 ${\alpha}_1$-, 3 ${\alpha}_2$-, 2 ${\beta}_1$-, ${\beta}_2$-, and 1 ${\gamma}$-globulin (Fig. 7, 9). In micro double diffusion test, five to six precipitation bands could be seen between antigens and antibody, the order of the precipitation bands location is albumin, ${\alpha}$-, ${\beta}$-, and ${\gamma}$-globulin from the side of antiserum well (Fig.19). Frequently the ${\alpha}$-, and ${\beta}$-precipitation bands were separated into two or three precipitation bands, which indicated that these globuline are not a pure component antigenically as shown in immuno-electrophoresis. In both Immunological methods, the two ${\alpha}$-, ${\beta}$-precipitin arcs and bands appeared clear and strong, indicating that the two globulins reacted as strong antigens. The precipitate reaction of ${\gamma}$-globulin was shown at 12 to 16 percent sodium sulfate; ${\beta}$-globulin at 12 to 20 percent; ${\alpha}$-globulin at 12 to 22 percent (immuno-electrophoresis), at 12 to 26 percent (Diffusion); and albumin at above 22 percent. Antigenically euglobulin contained ${\gamma}$-, ${\beta}$-, and ${\alpha}$-globulins, Pseudoglobulin I and Pseudoglobulin II were composed of ${\alpha}$-, and ${\beta}$-globulins, and albumin was a mixture of ${\alpha}$-globulin and albumin determined by zone electrophoresis. The results indicated that the fractions of serum protein obtained by either method were constituents of various proteins antigenically except ${\gamma}$-globulin and albumin by Zone electrophoresis.

• Journal of the Korean Ceramic Society
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• v.43 no.9 s.292
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• pp.575-581
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• 2006

To precipitate the complex gel of flux and aluminum hydroxides gel, aqueous solution of the mixture of $Na_2CO_3\;and\;Na_2PO_4{\cdot}12H_2O$ was added with stirring in aqueous solution of the mixture of $Al_2(SO_4)_3{\cdot}14{\sim}18H_2O,\;Na_2SO_4$, and then the complex gel was aged in $0{\sim}30h\;at\;90^{\circ}C$. As aging time passed, the aluminum hydroxides was grown into the acicular AlO(OH) gel. Also, aging time had an effect on physical properties of the AlO(OH) gel and on crystal growth of the flaky ${\alpha}-Al_2O_3$ prepared by molten-salt precipitation. In this study, the complex gel was crystallized in temperature range of $400{\sim}1,200^{\circ}C$ after drying at $110^{\circ}C$, and then it was investigated to effect of aging time on precipitation temperature, size, thickness, morphology and particle size distribution of the flaky ${\alpha}-Al_2O_3$ crystal. As aging time passed, the flaky a${\alpha}-Al_2O_3$ crystal showed a tendency toward an increase in size and thickness as result from an increase in BET surface area and pore volume of the acicular AlO(OH) gel.