• Journal of the Korean Ceramic Society
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• v.53 no.6
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• pp.604-609
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• 2016

This study reports on wet-foam stability with respect to porous ceramics from a particle-stabilized colloidal suspension that is achieved through the addition of polymethyl methacrylate (PMMA) using a wet process. To stabilize the wet foam, an initial colloidal suspension of $Al_2O_3$ was partially hydrophobized by the surfactant propyl gallate (2 wt.%) and $SiO_2$ was added as a stabilizer. The influence of the PMMA content on the bubble size, pore size, and pore distribution in terms of the contact angle, surface tension, adsorption free energy, and Laplace pressure are described in this paper. The results show a wet-foam stability of more than 83%, which corresponds to a particle free energy of $2.7{\times}10^{-12}J$ and a pressure difference of 61.1 mPa for colloidal particles with 20 wt.% of PMMA beads. It was possible to control the uniform distribution of the open/closed pores by increasing the PMMA content and by adding thick struts, leading to the achievement of a higher-stability wet foam for use in porous ceramics.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.21 no.1
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• pp.19-37
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• 1995

A fine oil -in-water (O/W) emulsion using non-aqueous emulsification technique was developed. And the behaviors of POE(25)octyldodecyl ether in non-aqueous polyol/oil systems were studied by observing the surface tension, interfacial tension, turbidity and transition temperature. It was found that POE(25)octyldodecy1 ether hardly existed as the micelle in the non-aqueous polyol system while, in water, it formed micelles very easily. So, when a polyol, like glycerine in which POE(25)octyldodecyl ether has a poor solubility, was added, POE(25)octyldodecyl ether moved to the surface. After saturated at surface, POE(25)octyldodecyl ether began to precitate. The mean particle size of the final emulsion was 230nm. Also, the emulsion system was stable at 0$^{\circ}C$, 25$^{\circ}C$, 40$^{\circ}C$, 50 $^{\circ}C$ and freeze-thaw cycle chamber for a month, while a conventional emulsion system was unstable. It is concluded that, by pertinent combination of polyols, we can improve the adsorption efficiency of surfactant.

• Journal of the Korean GEO-environmental Society
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• v.15 no.12
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• pp.61-69
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• 2014

Carboxymethyl-${\beta}$-cyclodextrin (${\beta}$-CMCD), as a biodegradable surfactant with hydrophobic and hydrophilic properties, has potential advantages of being applicable to the simultaneous treatment of multiple contaminated soils. In this study, the desorption behaviors of r adionuclides such as cobalt (Co), strontium (Sr), and cesium (Cs) from the soil contaminated with them were experimentally investigated and the effectiveness of CMCD as a desorbent was evaluated. The desorption equilibrium of used radionuclides could be achieved within 1~3 hr and the desorption ratio from kaolin was higher than that from natural soil. The addition of CMCD of 2 g/L increased the desorption ratio by 5~20 % and the desorption ratio of used r adionuclides was shown in the order of Co > Cs > Sr. The experimental desorption data were fitted successfully by pseudo-second order kinetic model and the desorption rate of the r adionuclides was shown in the order of Cs > Co > Sr. Hysteresis between adsorption and desorption of the r adionuclides, as shown in the order of Sr > Co > Cs, increased as the desorption rate decreased. Consequently, it could be considered that the desorption rate was one of the significant factors of the hysteresis. The addition of CMCD as desorbent increased the amount of desorbed radionuclides and decreased the hysteresis. However, the CMCD could not completely desorb the radionuclides from soils even though the excess of CMCD was added.

• Analytical Science and Technology
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• v.8 no.1
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• pp.1-7
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• 1995

Spectrophotometric determination of U(VI) and Th(IV) by Flow injection method is described. Chrome Azurol S forms water soluble complexes with U(VI) and Th(IV) in the presence of cethyltrimethylammonium bromide. The maximum adsorption of U(VI) and Th(IV) complexes are at 600nm with molar absorptivity of $2.3{\times}10^5Lmol^{-1}cm^{-1}$ and 611nm with molar absorptivity of $3.8{\times}10^5Lmol^{-1}cm^{-1}$ in acetate buffer medium having pH 5.0 and 5.5. The calibration curves of U(VI) and Th(IV) are linear over the range of 0.1~0.8ppm and the correlation coefficients are ca. 0.9960 and 0.9930 respectively. The detection limits(S/N) are 20ppb for U(VI) and 15ppb for Th(IV). The relative standard deviation are ${\pm}1.8%$ for U(VI) and ${\pm}2.1%$ for Th(IV). The sample throughput was ca. $50hr^{-1}$.