• Journal of Soil and Groundwater Environment
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• v.17 no.6
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• pp.59-68
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• 2012

This study provided sorption properties of chlorofluorocarbons (CFCs), and elucidated potential application of CFC sorption data in hydrogeochemistry. Prior sorption studies were reviewed for hydrophobic organic compounds similar to the CFCs, because there were only few CFC sorption studies. The CFCs are regarded as relatively conservative chemicals in groundwater environments based on their moderate hydrophobicity. However, thermally altered carbonaceous matter (TACM) can significantly increase sorption capacity and nonlinearity for hydrophobic organic compounds such as CFCs, compared to general soil organic matter. CFC sorption behavior are close to the sorption for reviewed organic chemicals. Therefore, the CFC sorption data can be used for determining hydrogeochemical properties and predicting transport of organic contaminants in TACM-containing aquifer environments.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.5
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• pp.30-36
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• 2013

Hydrophobic property of Kapok fiber was investigated by sequential removal of its components by different extraction methods. Acetone extraction for the removal of the hydrophobic extractives, holo-cel-lulose preparation after the removal of lignin and xylan extraction by potassium hydroxide was applied. The degree of hydrophobicity of each samples were measured by the water sorption ability. The water sorption ability of Kapok fiber was increased by the sequential treatment of acetone extraction, holocellulose preparation and xylan removal. Based on holocellulose compositional analysis by $^1H$-NMR spectroscopic method, the unusual high amount of the acetyl groups in the holocellulose of Kapok partially contributed to the hydrophobicity of Kapok holocellulose fiber.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.114-117
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• 2002

Sorption and desorption studies were conducted to evaluate several media as a potential biobarrier for the remediation of groundwater contaminated with hydrophobic organic compounds (HOCs). Pahokee and Bion peats, Devonian Ohio shale, vermicompost, and 50% HDTMA-montmorillonite were used as model sorbents. Sorption and desorption isotherms were determined using the radiolabeled phenanthrene (Phe). Sorption capacity of Phe on several sorbents was in the order Ohio shale > 50% HDTMA-montmorillonite > vermicompost > Pahokee peat. Mineralization kinetics was investigated for Phe-sorbed sorbents using Pseudomonas putida 17484. Among the tested sorbents, active biodegradation of Phe was observed in shale and vermicompost: degradation in shale exhibited little lag time while that in shale showed a significant lag time. Results of this study indicate that sorbents used in this work can be utilized as permeable reactive biobarrier media for the remediation of HOC-contaminated groundwater.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.26-29
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• 2001

Sorption/desorption Study was conducted to determine desorption-resistance hydrophobic organic compounds in natural soils with low organic carbon content. Sorption/desorption characteristics of chlorobenzene and phenanthrene for both PPI (Petro Processors, Inc. Superfund site) and BM (Bayou Manchac), soils were investigated. Desorption was biphasic including reversible and desorption-resistant compartments. The biphasic sorption parameters indicated the presence of appreciable size of desorption-resistant phase in these soils. A finite maximum capacity of desorption-resistant fraction (equation omitted) was observed after several desorption steps. The apparent organic carbon based Partition coefficient, K(equation omitted) was 10$^{4.92{\pm}0.27}$ for PPI soil and 10$^{4.92{\pm}0.27}$ for BM soil, respectively. The difference in K(equation omitted) was attributed to different characteristics in soil organic matter. The results suggest that desorption-resistance should be considered in remediation and risk assessments in natural soils and sediments.

• Journal of the Korean Solar Energy Society
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• v.35 no.4
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• pp.17-24
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• 2015

The formation of heat islands causes high energy demand for space cooling and peak cooling loads in conditioned buildings. High-temperature fluctuations on a building roof may cause mechanical stress and increase surface deterioration. Thermal energy storage (TES) systems using microencapsulated phase-change materials (MPCMs) have been recognized as one of the most advanced energy technologies for enhancing the energy efficiency and sustainability of buildings. In this study, we prepared MPCM/paint composites for mitigating the heat island effect and reducing peak temperature. In addition, we carried out thermal and physical analysis of prepared MPCM composite samples by means of SEM, FTIR spectroscopy, DSC, and TGA. Further, we evaluated the dynamic heat transfer performance of heat-storage tiles painted with 10 g of heat-storage paint. From the obtained results, we deduced that MPCM/hydrophilic paint composites are more applicable to various fields, including the building sector, than MPCM/hydrophobic paint composites. On the basis of SEM and FTIR spectroscopy results, we concluded that materials with hydrophilic properties are more compatible with MPCMs than those with hydrophobic properties. In addition, DSC analysis results revealed that MPCM/hydrophilic paint composites have better compatibility, higher latent heat capacity, and better thermal properties than other composites. TGA results showed that hydrophilic-paint-based composites have higher thermal durability than hydrophobic-paint-based composites. Finally, a lot of MPCM-loaded heat-storage tiles showed lower peak temperatures at all measurement positions.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.148.2-148.2
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• 2013

We prepared hydrophobic PDMS-coated porous silica as pre-concentration adsorbent for chemical warfare agents (CWAs). Since CWAs can be harmful to human even with a small amount, detecting low-concentration CWAs has been attracting attention in defense development. Porous silica is one of the promising candidates for CWAs pre-concentration adsorbent since it is thermally stable and its surface area is sufficiently high. A drawback of silica is that adsorption of CWAs can be significantly reduced due to competitive adsorption with water molecule in air since silica is quite hydrophilic. In order to solve this problem, hydrophobic polydimethylsiloxane (PDMS) thin film was deposited on silica. Adsorption and desorption of chemical warfare agent (CWA) simulants (Dimethylmethylphosphonate, DMMP and Dipropylene Glycol Methyl Ether, DPGEM) on bare and PDMS-coated silica were studied using temperature programed desorption (TPD) with and without co-exposing of water vapor. Without exposure of water vapor, desorbed amount of DMMP from PDMS-coated silica was twice larger than that from bare silica. When the samples were exposed to DMMP and water vapor at the same time, no DMMP was desorbed from bare silica due to competitive adsorption with water. On the other hand, desorbed DMMP was detected from PDMS-coated silica with reduced amount compared to that from the sample without water vapor exposure. Adsorption and desorption of DPGME with and without water vapor exposing was also investigated. In case of bare silica, all the adsorbed DPGME was decomposed during the heating process whereas molecular DPGME was observed on PDMS-coated silica. In summary, we showed that hydrophobic PDMS-coating can enhance the adsorption selectivity toward DMMP under humid condition and PDMS-coating also can have positive effect on molecular desorption of DPGME. Therefore we propose PDMS-coated silica could be an adequate adsorbent for CWAs pre-concentration under practical condition.

• Proceedings of the Korean Fiber Society Conference
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• 2003.10a
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• pp.51-52
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• 2003

In order to understand the buffering behavior of hygroscopic fabric under subzero conditions, microclimates of the wool and PET clothing system were measured and compared. Vertical type Man-Clothing-Environment simulator was used to measure the microclimate at the environmental temperature of -10$^{\circ}C$. Buffering capacity was quantified by calculating from the depth and width of the hyperbolic curve of the graph. Hydrophilic wool fabrics showed better buffering capacity at the transient state than hydrophobic PET fabrics; which is attributed to the heat of sorption.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.05a
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• pp.59-62
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• 2003

Kinds, shapes and fraction ratios of fibers have influence on properties of HPFRCC(High-Performance Fiver Reinforced Cementitious Concrete ) like bending strength, strain capacity and fracture toughness. For example, hydrophilic fibers have different chemical bond strength from hydrophobic fibers, fiber shapes influence on fiber pull-out and rupture, and fiber volume fraction influence on bending strength. In this study, to estimate influences of kinds, shapes and fraction ratios of fibers, we make HFRCC with 3 kind of fiber in various volume fraction of fiber and compare cracking, bending strength and fracture toughness. As the results, bending strength of HPFRCC was increased as fiber volume fraction was Increase and fiber tensile strength was increase, and strain capacity and fracture toughness of HFRCC was higher in fiber pull-out fracture than in fiber rupture fracture. And HFRCC showing pseudo strain hardening has higher fiber reinforce efficiency than others.

• Environmental Analysis Health and Toxicology
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• v.12 no.3_4
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• pp.75-84
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• 1997

Chromatographic retention behavior and separation of various phenol derivatives on a Partisil 10 ODS 3 column-with mobile phase containing $\alpha$-cyclodextrin-were systematically studied. The decrease in k' values caused by the addition of cyclodextrins in the mobile phase was based on the formation of an inclusion complex, resulting in weakening of the hydrophobic interaction between solutes and the stationary phase. The content of the organic solvent in the mobile phase also influenced k' values of the solutes, and k' values increased with a decrease of the content of organic solvent in the mobile phase. A simple equation has been derived that reveals the hyperbolic dependence of the capacity factor on the total concentration of cyclodextrin. A plot of the reciprocal of the capacity factor against (CD)$_T$ gives a straight line and the dissociation constant, K$_D$, of the inclusion complex can be calculated from the slope. The capacity factor decreased with increasing temperature. The enthalpy was calculated from the slope of van't Hoff plots. Under optimum conditions, some mixtures of phenol derivatives were able to separated successfully.

• 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.