• Korean Journal of Materials Research
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• v.29 no.3
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• pp.143-149
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• 2019

To develop flexible adsorbents for compact volatile organic compound (VOC) air purifiers, flexible as-spun zeolite fibers are prepared by an electrospinning method, and then zeolite particles are exposed as active sites for VOC (toluene) adsorption on the surface of the fibers by a thermal surface partial etching process. The breakthrough curves for the adsorption and temperature programmed desorption (TPD) curves of toluene over the flexible zeolite fibers is investigated as a function of the thermal etching temperature by gas chromatography (GC), and the adsorption/desorption characteristics improves with an increase in the thermal surface etching temperature. The effect of acidity on the flexible zeolite fibers for the removal of toluene is investigated as a function of the $SiO_2/Al_2O_3$ ratios of zeolites. The acidity of the flexible zeolite fibers with different $SiO_2/Al_2O_3$ ratios is measured by ammonia-temperature-programmed desorption ($NH_3-TPD$), and the adsorption/desorption characteristics are investigated by GC. The results of the toluene adsorption/desorption experiments confirm that a higher $SiO_2/Al_2O_3$ ratio of the flexible zeolite fibers creates a better toluene adsorption/desorption performance.

• Membrane and Water Treatment
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• v.14 no.2
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• pp.95-106
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• 2023

In the developing country like India, groundwater is the main sources for household, irrigation and industrial use. Its contamination poses hydro-geological and environmental concern. The hazardous waste sites such as landfills can lead to contamination of ground water. The contaminants existing at such sites can eventually find ingress down through the soil and into the groundwater in case of leakage. It is necessary to understand the process of migration of pollutants through sub-surface porous medium for avoiding health risks. On this backdrop, the present paper investigates the behavior of pollutants' migration through porous media. The laboratory experiments were carried out on a soil-column model that represents porous media. Two different types of soils (standard sand and red soil) were considered as the media. Further, two different solutes, i.e., non-reactive and reactive, were used. The experimental results are simulated through numerical modeling. The percentage variation in the experimental and numerical results is found to be in the range of 0.75- 11.23 % and 0.84 - 1.26% in case of standard sand and red soil, respectively. While a close agreement is observed in most of the breakthrough curves obtained experimentally and numerically, good agreement is seen in either result in one case.

• Carbon letters
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• v.2 no.1
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• pp.9-14
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• 2001

Adsorption and desorption characteristics of methyl iodide at high temperature conditions up to $250^{\circ}C$ by TEDA-impregnated activated carbon, which is used for radioiodine retention in nuclear facility, was experimentally evaluated. In the range of temperature from $30^{\circ}C$ to $250^{\circ}C$, the adsorption capacity of base activated carbon decreased sharply with increasing temperature but that of TEDA-impregnated activated carbon showed higher value even at high temperature ranges. Especially, the desorption amount of methyl iodide on TEDA-impregnated carbon represented lower value than that on unimpregnated carbon. The breakthrough curves of methyl iodide in the fixed bed packed with base carbon and TEDA-impregnated activated carbon at high temperature were compared. TEDA-impregnated activated carbon would be applicable to adsorption process up to $150^{\circ}C$ for the removal of radioiodine in a nuclear facility.

• Nuclear Engineering and Technology
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• v.44 no.1
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• pp.79-88
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• 2012

Migration tests were performed with conservative tracers in a fractured zone that had a single fracture of about 2.5 m distance at the KURT. To interpret the migration of the tracers in the fractured rock, a solute transport model was developed. A two dimensional variable aperture channel model was adopted to describe the fractured path and hydrology, and a particle tracking method was used for solute transport. The simulation tried not only to develop a migration model of solutes for open flow environments but also to produce ideas for a better understanding of solute behaviours in indefinable fracture zones by comparing them to experimental results. The results of our simulations and experiments are described as elution and breakthrough curves, and are quantified by momentum analysis. The main retardation mechanism of nonsorbing tracers, including matrixdiffusion, was investigated.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.111-114
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• 2003

A new monitoring system has been developed for in-situ and realtime measurement of ozone transport in unsaturated porous media using a fiber optic sensor. The calibration of the fiber optic transflection dip probe (FOTDP) system was successfully carried out at various ozone concentrations using a column with length of 30 cm and diameter of 5 cm packed with glass beads, which don't react with gaseous ozone. The breakthrough curves (BTCs) of ozone was obtained by converting the normalized intensity into ozone concentration. The FOTDP system reflected the ideal transport phenomena of gas phase ozone at various flow rates. The FOTDP system worked well for in-situ monitoring of gas phase ozone at various water saturations and in presence of SOM. However, the FOTDP system did not measure the ozone concentration at more than 70% water saturation.

• Clean Technology
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• v.8 no.2
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• pp.93-99
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• 2002

Adsorption dynamics for toluene and trichloroethylene with an isothermal fixed bed of activated carbon fiber were investigated. Equilibrium isotherms were measured by a static method for toluene and trichloroethylene onto activated carbon fiber at temperatures of 298, 323, and 348 K and pressure up to 3 kPa for toluene and 6 kPa for trichloroethylene, respectively. These results were correlated by the Toth equation. And dynamic experiments in an isothermal condition of 298 K were examined. Breakthrough curves reflected the effects of the experimental variables such as partial pressures for adsorbate and interstitial bulk velocities of gas flow. To present the column dynamics, a dynamic model based on the linear driving force (LDF) mass transfer model was applied.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1512-1517
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• 2008

Laboratory column tests were conducted in this study using $Cl^-$ tracers on Jumunjin sand to analyze contaminant transport in mixed contaminated soils. Results obtained from clean soils and soils containing residual diesel verified heterogeneous distribution of residual diesel, and clear acceleration of solute movement. In addition, asymmetric breakthrough curves indicated development of immobile region where solute movement becomes stagnant and creates tailing phenomenon.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09c
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• pp.140-145
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• 2010

Consolidation in cohesive soils mainly focuses on compressibility of soils, but it affects solute transport in some cases. The consolidation process takes on particular significance for fine grained soils at high water content, such as dredged sediments, but has also been shown to be important for compacted clay liners during waste filling operation. Numerical investigation using CST1 and CST2 was reviewed on consolidation-induced solute transport in this paper, especially with the development of CST2 model, verification by comparing experimental results with numerical simulations, and cases studies regarding transport in a confined disposal facility (CDF) and during in-situ capping. The importance of the consolidation process on solute transport is accessed based on simulated concentration or mass breakthrough curves. Results indicate that neglecting transient consolidation effects may lead to significant errors in transport analyses, especially with soft contaminated cohesive soils undergoing large volume change.

• Environmental Engineering Research
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• v.10 no.2
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• pp.71-78
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• 2005

A series of column experiments was conducted to develop a monitoring system for in-situ and realtime measurement of ozone transport in unsaturated porous media using a fiber optic sensor. The calibration of the fiber optic transflection dip probe (FOTDP) system was successfully carried out at various ozone concentrations using a column with length of 30 cm and diameter of 5 cm packed with glass beads, which don't react with gaseous ozone. The breakthrough curves (BTCs) of ozone were obtained by converting the normalized intensity into ozone concentration. The FOTDP system worked well for in-situ monitoring of gas phase ozone at various water saturations and in presence of soil organic matter (SOM). However, the FOTDP system did not measure the ozone concentration at more than 70% water saturation.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.9
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• pp.505-512
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• 2017

The adsorption characteristics of Sr ion in aqueous solution was examined using zeolite NaA powder (Z-PA) and pellets (Z-BA). In batch experiment, the adsorption of Sr ions by Z-BA and Z-PA was well expressed by pseudo-second-order kinetic model than psedo-first-order kinetic model. Experimental isotherm results was well fitted to Langmuir isotherm model and the maximum adsorption capacities obtained from Langmuir isotherm model were 233.32 mg/g for Z-PA and 164.60 mg/g for Z-BA, respectively. The continuous experiment results showed that the total Sr ion uptake (q) increased, but the breakthrough time, effluent volume ($V_{eff}$) and total removal (R) of Sr ion decreased with the Sr ion concentration. The breakthrough curves obtained from the experiment was modeled by Thomas model.