• Journal of Powder Materials
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• v.23 no.4
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• pp.311-316
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• 2016

$Ni(OH)_2$ hollow spheres have been prepared by solvent displacement crystallization using a micro-injection device, and the effect of process parameters such as concentration and the relative ratio of the injection speed of the precursor solution, which is an aqueous solution of $NiSO_4{\cdot}6H_2O$, to isopropyl alcohol of displacement solvent have been investigated. The crystal phases after NaOH treatment are in the ${\beta}-phase$ for all process parameters. A higher concentration of $NiSO_4{\cdot}6H_2O$ aqueous solution is injected by a micro-injection device and bigger $Ni(OH)_2$ hollow spheres with a narrower particle size distribution are formed. The crystallinity and hardness of the as-obtained powder are so poor that hydrothermal treatment of the as-obtained $Ni(OH)_2$ at $120^{\circ}C$ for 24 h in distilled water is performed in order to greatly improve the crystallinity. It is thought that a relative ratio of the injection speed of $NiSO_4{\cdot}6H_2O$ to that of isopropyl alcohol of at least more than 1 is preferable to synthesize Ni(OH)2 hollow spheres. It is confirmed that this solution-based process is very effective in synthesizing ceramic hollow spheres by simple adjustment of the process parameters such as the concentration and the injection speed.

• Journal of the Korean Society for Heat Treatment
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• v.5 no.4
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• pp.224-232
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• 1992

Coolingability of coolants is important factor in cooling processor heat treatment of steel. Using standard apparatus and method defined in the Korean Industrial Standard three different shapes of probe were designed, ie, cylinderical, spherical and square on shape with same volume of standard probe. Distilled water and sodium aquious solutions with different concentration of NaOH, NaCl and $Na_2CO_3$ were examined. Estimation of coolingability of each quenchants for the probes of cylinderical, spherical or square shape, the cooling rate is greater square, cylinder and sphere in order. Coolingability of sodium aquious solution of NaCl, $Na_2CO_3$ and NaOH is found generally greater then that of distilled water. Effectiveness of ingredients is in the order of $Na_2CO_3$, NaOH and NaCl. In both solutions coolingability increases in 20%, 5%, and 10%in order. Analytical results obtained from Finite Element Method were compared with experimental ones and found as practically satisfactional.

• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.618-623
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• 2003

Solvent extraction experiments for separation of impurities from Ni-rich solution were carried out for manufacturing of high purity Ni compounds from acid leaching solution of spent Ni-Cd secondary battery. Artificial and leaching solutions were used as aqueous phases and PC88A saponified by sodium in kerosene were used as organic phase. The extraction order is Zn>Mn>Co>Ni and extraction percentage of metal ions was increased with increase of the concentration of extractant, initial pH of aqueous phase and ratio of O/A. The separation of cobalt, zinc and manganese from nickel was effectively accomplished at the condition of extraction stage=l, O/A=1 and initial pH 5.0 with 1.0 $mol/dm^3$ PC88A saponified to $50\%$ with NaOH.

• Journal of the Mineralogical Society of Korea
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• v.5 no.2
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• pp.61-71
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• 1992

Through the low-temperature(60-150${\circ}C$) hydrothermal treatment of perlite with the alkaline solution at various NaOH concentrations, the mode of volcanic glass alteration and resultant zeolite formation were investigated in a closed system. At a temperature of 80${\circ}C$ and alkalinities of pH range 8 to 12, corresponding to the natural environments of diagenetic zeolite formation, only weak dissolution of perlitic glass occurs without zeolite formation despite the residence time of 100 days. Activities of Si and Al increase progressively, as a consequence of increasing pH, whereas activity ratios of Si/Al decrease. Zeolites were synthesized from perlite in the alkaline solution at above 0.1M NaOH concentrations. Below the temperature of 100${\circ}C$ Na-P was mainly formed, whereas analcime was the dominant zeolite at the temperature range of 100-150${\circ}C$. During Na-P synthesis chabazite and Na-X were also formed as by-products in case of lower proportion of solution/sample(<10ml/g) and higher NaOH concentraion (>3M), respectively. The alteration modes of perlite in the zeolite synthesis reflect that the formation of synthetic zeolites occurs as an incongruent dissolution likely with the diagenetic formation of natural zeolites from volcanic glass. Considering much difference in reaction kinetics between natural and synthetic systems, however, the evaluated synthetic conditions in these experiments were not directly applicable to the natural diagenetic system.

• Journal of the Korean Ceramic Society
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• v.44 no.10
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• pp.562-567
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• 2007

To precipitate the complex gels of the pH 6, 7, 8, 9 included in a flux and an aluminum hydroxides gel, an aqueous solution of a mixture of $Na_2CO_3\;and\;Na_2PO_4{\cdot}12H_2O$ was added with stirring in an aqueous solution of a mixture of $Al_2(SO_4){_3}{\cdot}18H_2O,\;Na_2SO_4\;and\;K_2SO_4$, and then the complex gels were aged in 20 h at $90^{\circ}C$. As the hydrolysis pH changed, it had an effect on the physical properties such as the crystal structure, crystal morphology and a phase transition temperature of the AlO(OH) gel, and also on the crystal structure, crystal morphology, particle size and particle size distribution of the ${\alpha}-Al_2O_3$ platelets prepared by molten-salt precipitation. Also, in this study, the complex gels were crystallized at $1,200^{\circ}C$ and thereafter dried at $110^{\circ}C$, and then it was investigated to effect of the hydrolysis pH on the crystal structure, morphology and particle size distribution of the ${\alpha}-Al_2O_3$ platelets crystals using XRD, DTA, SEM and particle size analyzer.

• Membrane and Water Treatment
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• v.3 no.4
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• pp.243-252
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• 2012

Tri-n-butyl phosphate (TBP) was used as carrier for the transport of Golden yellow and Cibacron LSG dyes through a hexane bulk liquid membrane. The transport efficiency of dyes by TBP was investigated under various experimental conditions such as pH of the feed phase (dyes solution), concentration of the receiving phase (NaOH solution), concentration of TBP in membrane, rate of stirring, effect of transport time, type of solvent, dye concentration in feed phase, effect of temperature.. The maximum transport dyes occurs at ratio of 1:1 TBP-hexane At pH 3.0 0.1 (feed phase) the transport dyes decreased. At high stirring speed (300 rpm) the dyes transport from the feed phase to the strip phase was completed within 60 minutes at $27^{\circ}C$. Under optimum conditions: Feed phase 100 mg/L dyes solution at pH 1.0 0.1, receiving phase 0.1 mol/L NaOH solution, membrane phase 1:1 TBP-hexane , Stirring speed 300 rpm and temperature $27^{\circ}C$, the proposed liquid membrane was applied to recover the textile effluent.

• Korean Journal of Materials Research
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• v.8 no.4
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• pp.368-374
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• 1998

The corrosion characteristics of zirconium alloys have been investigated in various aqueous solutions of LiOH. NaOH, KOH, RbOH. and CsOH at 3S$0^{\circ}C$. The concentrations of solutions were set to 4.3 mmol and 32.Smmol with equimolar $M^+$ and OH . The oxide characterization was performed using TEM on the samples corroded in 32. Smmol LiOH, NaOH, and KOH solution. The samples were prepared to have the same oxide thickness for the pretransition and post- transition regimes. Considering the trend of experimental data, the cation would playa major role in the corrosion process of Zr alloys in alkali hydroxide solutions. The microstructures of the oxides formed in various solutions were quite different. In LiOH solution the oxides grown in pre-transition as well as post-transition had the equiaxed structures with many pores and open grain boundaries. The oxides grown in NaOH solution had the protective columnar structures in pre-transition and the equiaxed structures with many open grain boundaries in post- transition. On the other hand. in KOH solution the columnar structure was maintained from pre- transition to post- transition. It was considered that the cation incorporation into zirconium oxide controlled the oxide characteristics and the corrosion acceleration in alkali hydroxide solutions.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2008.04a
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• pp.77-79
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• 2008

Polynitro fullerenes were synthesized by reaction C-60 in benzen solution with a mixture of NaNO$_2$ and HNO$_3$. Hydrolysis of polynitro fullerenes in aqueous NaOH gave the corresponding polyhydroxylated fullerenes. Sulfonation reaction was carried out in pyridine solution of ClSO$_3$H. Infrared spectra of the resultant fullerene derivatives showed the characteristic IR bands, corresponding to absorptions of O-H, N-O, and SO$_3$Na functions. Electric resistivity and thermal transmittance of wool fiber absorbed with the water-soluble C-60 were investigated. Thermal transmittances of wool fiber were increased with increasing water-soluble C-60 concentrations, but electric conductivity were decreased with raising water-soluble C-60 uptake values.

• YAKHAK HOEJI
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• v.25 no.1
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• pp.1-7
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• 1981

Glycyrrhizin (GA) content in licorice was determined by a couple of methods using HPLC, respectively. In Method(I), GA content itself was determined from the licorice aqueous extract, while in Method (II) glycyrrhetinic acid (GHeA ; the aglicone of GA) content corresponding to the quantity of GA was measured from the chloroform extract of the hydrolyzed product of licorice aqueous extract. A reverse phase column Hibar Lichrosorb RP-18 (E. Merck) was used as the stationary phase. As the mobile phase MeOH: $H_{2}O$(0.05M-$NaH_{2}PO_{4}$)=58 : 42 solution in Method (I), and MeOH: $H_{2}O $: AcOH=78; 19: 3 solution in Method (II) were suitable, respectively. The value obtained by Method (II) appeared slightly higher than that by Method (I). The effect of some other herbal drugs on the assay of GA quantity in mixed sample was also observed in both above two methods. By Method (I) Cassiae Cortex, Rehmaniae Rhizoma, Paeoniae Radix, and Angelicae Radix gave the subtractive effect on the amount of GA compared with the value from licorice alone. In the case of Method (II) Cassiae Cortex and Rehmaniae Rhizoma appeared to have subtractive effect but Paeoniae Radix and Angelicae Radix scarcely showed any influence. Pachymae Fungus did not affect the GA content at all. It seems that glycyrrhizin in licorice interacts with certain components of other herbal drugs.

• Korean Journal of Materials Research
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• v.21 no.11
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• pp.587-591
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• 2011

The effect of the precipitator (NaOH, $NH_4OH$) and the amount of the precipitator (150, 200, 250, 300 ml) on the formation of $Fe_3(PO_4)_2$, which is the precursor used for cathode material $LiFePO_4$ in Li-ion rechargeable batteries was investigated by the co-precipitation method. A pure precursor of olivine $LiFePO_4$ was successfully prepared with coprecipitation from an aqueous solution containing trivalent iron ions. The acid solution was prepared by mixing 150 ml $FeSO_4$(1M) and 100 ml $H_3PO_4$(1M). The concentration of the NaOH and $NH_4OH$ solution was 1 M. The reaction temperature (25$^{\circ}C$) and reaction time (30 min) were fixed. Nitrogen gas (500 ml/min) was flowed during the reaction to prevent oxidation of $Fe^{2+}$. Single phase $Fe_3(PO_4)_2$ was formed when 150, 200, 250 and 300 ml NaOH solutions were added and 150, 200 ml $NH_4OH$ solutions were added. However, $Fe_3(PO_4)_2$ and $NH_4FePO_4$ were formed when 250 and 300 ml $NH_4OH$ was added. The morphology of the $Fe_3(PO_4)_2$ changed according to the pH. Plate-like lenticular shaped $Fe_3(PO_4)_2$ formed in the acidic solution below pH 5 and plate-like rhombus shaped $Fe_3(PO_4)_2$ formed around pH 9. For the $NH_4OH$, the pH value after 30 min reaction was higher with the same amount of additions of NaOH and $NH_4OH$. It is believed that the formation mechanism of $Fe_3(PO_4)_2$ is quite different between NaOH and $NH_4OH$. Further investigation on this mechanism is needed. The prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and the pH value was measured by pH-Meter.