• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.339-339
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• 2006

In this study, the microvoids in glassy polymers were investigated by Xe sorption and $^{129}Xe$ NMR measurements. Xe sorption isotherms of glassy polymers have been successfully interpreted by the dual-mode sorption model. $^{129}Xe$ NMR chemical shift of the $^{129}Xe$ in the samples show nonlinear low-field shift with increasing sorption amount of Xe because of a fast exchange of Xe atoms between Henry and Langmuir sites, whereas it has showed linear shift against sorption amount of Xe into the Langmuir site. From this Xe-density dependence of the $^{129}Xe$ NMR chemical shift, it has been able to estimate mean size of the microvoids in glassy polymer. It is confirmed that there is correlation between ${C_H}'$ and volume or number of microvoids. From these findings, it is demonstrated that $^{129}Xe$ NMR spectroscopy is a powerful technique to determine the mean size and number of microvoids in glassy polymers.

• Journal of the Korean Wood Science and Technology
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• v.44 no.2
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• pp.191-203
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• 2016

To investigate the dynamic sorptive and hygroexpansive behaviors of wood by different cyclic hygrothermal changing effects, poplar (populus euramericana Cv.) specimens, were exposed to dynamic sorption processes where relative humidity (RH) and temperature changed simultaneously in sinusoidal waves at 75-45% and $5-35^{\circ}C$ (condition A) and where RH changed sinusoidally at 75-45% but temperature was controlled at $20^{\circ}C$ (condition B), both for three cyclic periods of 1, 6, and 24 h. Moisture and dimensional changes measured during the cycling gave the following results: Moisture and transverse dimensional changes were generally sinusoidal. Moisture and dimensional amplitude increased with increasing cyclic period but all were lower for thicker specimens. The amplitude ratio of condition A to condition B ranged from 1.0 to 1.6 with the maximum value of 1.57 occurring at the shortest cyclic period, not as much as expected. T/R increased as cyclic period increased or specimen thickness decreased. T/R from condition B was weaker than that from condition A. Sorption and swelling hysteresis existed in both conditions. Sorption hysteresis was negatively related to cyclic period but in positive correlation with specimen thickness. Sorption hysteresis was found more obvious in condition B, while moisture sorption coefficient and humidity expansion coefficient showed the opposite results.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.42-45
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• 2005

Accurate prediction of the fate and transport of contaminants in soils and sediments is very Important to environmental risk assessment and effective remediation of contaminated soils and sediments. The fate and transport of contaminants in subsurface are affected by geosorbents, especially carbonaceous materials including black carbon. Various physical and chemical treatment methods have been developed to separate different kinds of carbonaceous materials from soils and sediments. However, the effects of these separation methods on the properties of remaining carbonaceous materials including sorption capacity and linearity are unclear. The objective of this study is to determine if the chemical and thermal treatment methods previously used to separate different carbonaceous material fractions affect the properties of carbonaceous materials including longer term sorption capacity of hydrophobic organic contaminants. The results indicate that treatments with hydrochloric acid (HCl)/hydrofluoric acid (HF), trifluoroacetic acid (TFA), sodium hydroxide (NaOH) may not affect the sorption capacity of black carbon reference materials such as char and soot, however, treatments with acid dichromate $(K_2Cr_2O_7/H_2SO_4)$ and heat $(375^{\circ}C)$ for 24 hours in sufficient of oxygen) decrease the sorption capacity of them. The results of longer term sorption isotherm indicate that 2 days might be enough for trichloroethene (TCE) to equilibrate apparently with treated black carbon reference materials. The results suggest that acid dichromate and heat treatments may not appropriate method to investigate sorption properties of black carbon in soils and sediments.

• Korean Journal of Materials Research
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• v.16 no.2
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• pp.116-122
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• 2006

The effects of milling time in argon and hydrogen atmospheres on the hydrogen sorption speed of a getter alloy, $Zr_{57}V_{36}Fe_{7}$, was studied. The hydrogen sorption speed of milled alloys was evaluated at room temperature. In argon, as the oxygen content increased with milling time, the hydrogen sorption speed decreased accordingly. In hydrogen, on the other hand, the oxygen content decreased at first with milling time but started increasing after 5 hrs of milling time. Similar to the case of argon, however, the hydrogen sorption speed changed exactly in the opposite direction with the oxygen content, exhibiting the maximum rate at 5 hrs. These results suggest that in both atmospheres the hydrogen sorption speeds are inversely related with the oxygen contents.

• Korean Journal of Agricultural Science
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• v.23 no.2
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• pp.250-260
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• 1996

Observed results of the adsorption between two competing anions for the shared sorption sites represent that the adsorption phenomena may depends on the characteristics of anion and available sorption sites in a given conditions. In binary systems, adsorption of one species can significantly influence the fate of the other anion, resulting in control of the extent of solute-adsorbate distributions throughout soil profile. And the proton-donation mechanisms by organic anions having a carboxyl as a functional group can also influence the adsorption of inorganic anions onto the hydroxylated sites of Fe and Al oxides. However, study of competitive adsorption of specifically adsorbed anions illustrates some of difficulties which arise in interpretation of reactions at oxide/aqueous solution interfaces. At least two factors prevented a simple analysis of reactions. First, at any pH value the maximum amount of adsorbate taken up at the surface depends on the identity of the anion. Second, it was necessary to postulate the sorption sites where the anion can be adsorbed. Hence, anions having non-specific adsorption characteristics are less capable for sorption sites, compared to those of specific adsorption characteristics, even though competition complies both ordinary and electrostatic interactions for sorption sites. Therefore, competition among chemical species in soil matrix can be of major significance in determining the effective mobility of any reactive anions with sorption sites.

• Fibers and Polymers
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• v.5 no.4
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• pp.280-288
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• 2004

Split-type nylon/polyester microfiber and polyester microfiber fabrics possess drapeability, softness, bulkiness, and smoothness, so that they can be applied in various industrial fields. In particular, these fabrics are able to absorb various organic solvents, and can be used as clean room materials. To investigate the chemical affinity between solvents and the compositional materials of these fabrics, the contact angle of thermally pressed film fabrics was measured with different solvents. The thermally pressed nylon/polyester fabric films showed a chemical attraction to formamide. The sorption properties of the microfiber fabrics were investigated using a real time testing device, and these tests showed that the sorption behavior was more influenced by the structure of the fibrous assembly than by any chemical attraction. The effect of the fabric density, specific weight, and sample structure on the sorption capacity and rate was examined for various organic solvents. The sorption capacity was influenced by the density and the specific weight of the fibrous assembly, and knitted fabric showed a higher sorption capacity than woven fabric. However, the sorption rate was less affected in lower viscosity solvents. On applying Poiseuille's Law, the lower viscosity solvents showed higher initial sorption rates, and more easily penetrated into the fibrous assembly.

• The Journal of the Korean dental association
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• v.57 no.5
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• pp.264-268
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• 2019

Objectives: This study aimed to measure the water sorption / solubility of Biodentine, composite resin and glass ionomer cement. Materials and Methods: The materials used in this study were Biodentine(BD), Filtek Z250(FZ) and Ketac Molar(KM). Twenty disc-shaped specimens of each material were prepared of 6mm diameter and 1mm thickness. All specimens were desiccated for 24 hours and weighed(m1). After then, They were immersed in distilled water and stored at $37^{\circ}C$. 1 week later, They were washed with running water, wiped with absorbent paper and weighed(m2). Finally, They were dried for 24 hours and weighed(m3). Water sorption and solubility, net water uptake were calculated. Results: KM and BD showed high water sorption than FZ(P<0.05). KM and BD exhibited similar water sorption(P<0.05). BD exhibited high solubility than KM(P=0.012). BD exhibited high net water uptake than FZ(P=0.008). Conclusion: Biodentine showed higher water sorption, solubility and net water uptake than Filtek Z250 and Ketac Molar. Within limitation of this study, it is not recommended to use Biodentine for permanent restoration.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.19 no.1
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• pp.1-7
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• 2021

The pH dependence of sorption distribution coefficient (Kd) of Np(IV) on MX-80 in Ca-Na-Cl type solution with the ionic strength of 0.3 M, which was similar to one of the reference groundwaters in crystalline rock, was experimentally investigated under the reducing conditions. The overall trend of Kd on MX-80 was independent of pH at 5 ≤ pH ≤ 10 but increased as pH increased at pH ≤ 5. The 2-site protolysis non-electrostatic surface complexation and cation exchange model was applied to the experimentally measured pH dependence of Kd and the optimized surface complexation constants of Np(IV) sorption on MX-80 were estimated. The values of surface complexation constants in this work agreed relatively well with those in the Na-Ca-Cl solution previously evaluated, suggesting that compared to Na+, the competition of Ca2+ with Np(IV) for surface complexation on MX-80 was not much strong in Ca-Na-Cl solution. The sorption model well predicted the pH dependence of Kd values but slightly overestimated the sorption at the low pH region.

• Journal of the Korean earth science society
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• v.43 no.4
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• pp.532-538
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• 2022

Under anoxic conditions, this study investigated removal of dissolved As(III) by Si and Al oxides including natural sand, chemically washed sand (silica), alumina, and activated alumina. Despite the similar surface area, natural sand showed greater extents of As(III) sorption than chemically washed sand. This was likely due to the high reactivity of Fe(oxyhydr)oxide impurities on the surface of natural sand. For both sands, As(III) sorption was the greatest at pH 7.1, in agreement with the weakly dissociating tendency of arsenous acid. Also, the least sorption was observed at pH 9.6. At basic pH, elevated silicate, which originated from the dissolution of silica in sands, would compete with As(III) for sorption. Due to the highest surface area, activated alumina was found to quantitatively immobilize the initially added As(III) (6.0×10^-7-2.0×10^-5 M). Alumina showed As(III) sorption compared to or greater than chemically washed sand, although the former had less than 6% of the surface of area the latter. The greater reactivity of alumina than chemically washed sand can be explained by using the shared charge of oxygen.

• The Journal of Engineering Geology
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• v.13 no.3
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• pp.369-378
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• 2003

The statistical modeling was introduced to satisfy various experimental conditions on the sorption of heavy metals (Pb, Cu, Cd, and Zn) by clay minerals, i.e. kaolinite, illite and chlorite. The Box-Behnken model designed statistically was applied to determine a relative impact among three variables such as pH, HCO3(or K) concentration and initial concentration of heavy metals. The SAS program was used to obtain the statistical solution by surface response analysis. The results of a statistical sorption modelling indicated that pH is a strong impact of the variables influencing the sorption of heavy metals. A relative effect between an initial concentration of heavy metals and bicarbonate(or K) concentration is dependent on solution condition. The sorption edge of heavy metals as function of pH shows sigmoidal curve, and a great increase in the range of pH 6～8. The sorption sequence among heavy metals is Cu>Pb>>Zn>Cd. The solution chemistry exerts greater influence on the sorption of heavy metals rather than the crystal chemistry of clay minerals. The potassium exerts some effect into a sorption competition with heavy metals. The research suggests that the statistical modeling is an effective method to demonstrate sorption results in three dimension and to reduce the effort of batch sorption experiment.