• Korean Journal of Soil Science and Fertilizer
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• v.19 no.2
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• pp.115-121
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• 1986

This experiment was conducted to examined the effects of the physico-chemical and mineral-logical properties of paddy soil on the desorption of $Cs^{137}$ from radionuclide, $Cs^{137}$ absorbed soils. 1. Adsorption of $Cs^{137}$ by paddy soil was very much and exchangeable fraction of $Cs^{137}$ extracted by ammonium acetate was very high compared to the water soluble fraction. Exchangeable fraction of $Cs^{137}$ in paddy soil decreased with the increase of potassium application and increased proportionally with the increase of $Cs^{137}$ treatment. 2. The distribution of several forms of $Cs^{137}$ in soils depend on the soil type. Average-distribution rates of water soluble, exchangeable and non-exchangeable fractions of $Cs^{137}$ in soils were 5.9%, 17.1% and 77.0%, respectively. 3. The desorption of $Cs^{137}$ from adsorbed soils decreased with increase of pH and exchangeable cations of the soils, but it increased as organic matter and clay content increase in soil. 4. Non-exchangeable adsorption of $Cs^{137}$ was high in the soils of which both Illite and Vermiculite were dominant.

• Journal of the Korean Chemical Society
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• v.32 no.3
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• pp.171-178
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• 1988

The potential energy of adsorbate molecules in the main channel of $K^+$ ion exchanged zeolite L(K-L) was calculated. In K-L which adsorbs three molecules per unit cell, the interaction energies of $H_2O,\;NH_3,\;CH_3NH_2,\;(CH_3)_2NH,\;and\;(CH_3)_3N$ molecules with zeolite lattice are 61.11, 62.31, 65.68, 74.65, and 79.88kJ/mol, respectively. These values are less by 3.7∼12.6kJ/mol than $K^+$ ion affinities with adsorbing molecules. These results may be due to the facts that the electrostatic energies are reduced by the negative charge of the lattice oxygens. The distribution of adsorption sites of $NH_3$ and $CH_3NH_2$ in K-L was investigated by a technique of temperature programmed desorption. The experimental value of desorption energies of $NH_3$ and $CH_3NH_2$ on K-L are in good agreement with the theoritical values. It is concluded that the desorption of $NH_3$ and $CH_3NH_2$ on K-L is the first-order desorption with free readsorption.

• New & Renewable Energy
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• v.2 no.2 s.6
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• pp.60-68
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• 2006

소수 station의 수소분리정제를 위한 compact형 PSA 공정을 연구하였다. 기존 PSA 공정의 흡착탑이 차지하는 시스템의 공간을 줄이기 위하여 하나의 흡착탑 안에 다른 흡착탑을 넣어 흡착탑이 차지하는 공간을 최소화하였으며, 흡착탑 간의 열교환이 효과적으로 일어나도록 설계하였다. 수소 혼합물에 대한 활성탄으로 충진된 dual bed에서의 수소 혼합물에 대한 흡/탈착 동특성 실험을 실시하였으며, 시간에 따른 농도와 온도의 변화를 측정하였다. 수소 혼합물로는 $H_2/CO/CH_4/CO_2$ (69:2:3:26 vol.%) 를 사용하였으며, 흡착유량은 7LPM, 흡착압력은 9atm 조건에서 운전하였다. Inner bed와 outer bed의 성능은 각각의 열전달 특성의 차이로 인하여 다르게 나타났으나, 단일탑의 동특성보다는 우수한 성능을 보이고 있었다. 따라서 개발된 dual bed는 적은 부지를 차지하면서도, 보다 우수한 수소 분리 성능을 보일 수 있는 PSA 공정에 응용될 수 있음을 확인하였다.

• Korean Chemical Engineering Research
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• v.48 no.6
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• pp.752-756
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• 2010

Desorption reaction characteristics of the used activated carbons collected from painting process in Shiwha/Banwal industrial complex were investigated. Thermogravimetric analyzer was used to investigate the desorption characteristics. Activation energies and reaction orders for desorption reaction characteristics of used activated carbons were estimated by employing Friedman method and Freeman-Carroll method. In the used activated carbons collected from painting process, it was found that the activation energies were 20.6~43.2 kJ/mol in Friedman method and 12.3~26.5 kJ/mol in Freeman-carroll method, and reaction orders were 0.1~1.7.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.162-167
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• 2003

최근 수년간 유선 시뮬레이션은 연산 속도의 효율성과 수치 분산으로 인한 오차를 감소시킬 수 있는 장점으로 인해 많은 연구가 이루어졌으며 오염물의 거동을 모사 하는데 많이 사용되고 있다. 이 연구에서는 유선 시뮬레이션의 기법을 이용하여 1차의 비평형 흡착을 고려한 오염물 거동 수치 모사를 수행하였다. 1차의 비평형 흡착의 경우 흡착 계수에 따라 오염물의 이동 속도가 민감하게 반응하는 것을 확인할 수 있었고 흡착 계수의 값이 커질수록 오염의 전파 지연 효과가 크게 나타남을 알 수 있었다. 1차의 비평형 흡착의 경우에 평형 흡착과는 달리 오염이 진행되면서 오염물의 농도를 감소시키는 영향을 나타내었으며 이로 인하여 오염물이 더 이상 진행하지 못하는 제로라인을 형성하게 하였다. 이 제로라인은 흡착 계수의 값이 클수록 탈착 계수의 값이 작을수록 오염원에 가깝게 형성되었다.

• Journal of the Korean Chemical Society
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• v.48 no.6
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• pp.590-598
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• 2004

The preconcentration and determination of trace Cu(II) and Pb(II) on calcium alginate beads in aqueous solution were studied. A calcium alginate beads were prepared by adding an alginic acid to sample solution contained Ca(II). Some following conditions were optimized: the pH of sample solution, amount of alginic acid, and stirring time for effective adsorption; the type and concentration of acid, and sonication time in an ultrasonic vibrator for the perfect de-sorption. A sample solution was prepared with Cu(II) and Pb(II) in DI water. And Ca(II) and ethanol was added into the sample solution. The pH of the final sample solution was controlled with buffer solution. The alginic acid were dispersed in the sample solution by a magnetic stirrer. This mixture was stored in room temperature for 30 min to form a calcium alginate. After the beads were filtered and washed on a membrane filter, the analytes were redissolved from the beads by an ultrasonic vibration of 10 minutes in 1.0M $HNO_3$ solution. The effect of diverse ions on the adsorption of analytes were studied. This procedure was applied for the analysis of two real samples. The recoveries in spiked samples were $90.4{\sim}104.3%$ for analytes.

• The Korean Journal of Pesticide Science
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• v.2 no.3
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• pp.70-78
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• 1998

Dissipation, adsorption and desorption of oxadiazon were examined in two soils containing different amounts of soil organic matter. In addition, reactivity of oxadiazon with humic monomers was searched to clarify binding mechanism of oxadiazon to soil organic matter in the presence of a laccase of Myceliophthera thermophila. Half lives of oxadiazon were 38 days in Soil I and 45 days in Soil II. Freundlich constant, k values of fresh soils were higher than those of oxidized soils. Adsorption rates of oxadiazon were increased 17.1% in Soil I and 9.3% in Soil II in the presence of a laccase but no significant increase was observed in oxidized soils. Desorption rates of oxadiazon in fresh soils were lower than those in oxidized soils. Desorption rates of adsorbed oxadiazon in soils addes with the enzyme were not changed in oxidized soils but decreased in fresh soils. The herbicide oxadiazon alone underwent no transformation by a laccase but in the presence of catechol, guaiacol and gallic acid as humic monomer, transformation rates of it were from 20% to 24%.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.2
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• pp.279-285
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• 1993

It is important to understand the interrelationship between adsorption, equilibrium and mass transport in efficient design and operation of the granular activated carbon(GAC) adsorption systems. In this study, the micro-diameter-depth adsorption system(MIDDAS) technique was developed to estimate equilibrium and mass transport parameters, which were utilized to simulate adsorption and mass transport phenomena dynamically and mathematically. The homogeneous surface diffusion model(HSDM) utilizing the estimated equilibrium and mass transport parameters including the film transfer coefficients and surface diffusivities from the MIDDAS technique, successfully predicted competitive adsorption, desorption and chromatographic displacement effects. In the binary solute system of p-chlorophenol(PCP) and p-nitrophenol(PNP), PCP was displaced by PNP and the HSDM could predict successfully. While the HSDM described the desorption breakthrough curves for PCP, PNP and PTS well when complete reversible adsorption was assumed, the desorption breakthrough curves for DBS could be predicted after subsequent incorporation of the degree of irreversibility into the model simulations.

• Journal of Energy Engineering
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• v.4 no.1
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• pp.76-84
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• 1995

본 연구에서는 코코넛 껍질로부터 제조한 활성탄을 열 및 산소-암모니아의 혼합가스로 전처리하여 표면의 특성 변화와 이산화황 흡착능에 미치는 영향을 살펴보았다. 전처리한 활성탄으로 이산화황 흡착실험을 수행한 결과, 전처리한 활성탄은 기본 활성탄 시료보다 높은 흡착능력을 보였다. 본 연구의 전처리 실험에서는 산소와 암모니아를 주입하여 활성점을 제공하는 산소와 환원성 분위기를 조성하는 질소관능기를 도입하였다. 전처리 조건은 0∼25%의 암모니아와 473∼1273K의 온도이며 처리조건을 변화시킴으로써 표면 기능의 척도가 되는 세공구조와 원소조성 및 표면 관능기 등에 직접적인 영향을 주었다. 흡착능력은 고정층 반응기에서 전자 비틀림 저울로 이산화황 흡착량을 측정하여 비교하였고, 이 과정 중의 활성탄 표면의 특성변화를 원소분석, 승온탈착법, 산-염기 적정법, 주사현미경법 등의 분석 방법을 통해서 알아보았다. 그 결과, 이산화황의 최대 흡착 능력은 온도조건 973∼1173K에서 나타났다. 또한, 암모니아로 처리하지 않은 활성탄에 비하여 암모니아로 처리한 활성탄은 그 주입농도에 관계없이 이산화황의 흡착제거율을 약 48% 정도 향상시켰다.

• Journal of Sensor Science and Technology
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• v.1 no.2
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• pp.125-130
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• 1992

A resistive-type humidity sensors have been fabricated using cross-linked PMMA thin film as sensing material and their humidity characteristics have been investigated. The sensor coated of the cross-linked PMMA with PVA exhibited largely variation of resistance by increase of relative humidity and less than 3% of hysteresis. Furthermore, the fabricated sensor exhibited superior long-term stability. The response time of the PMMA humidity sensor was about 7 min. for adsorption and about 5 min. for desorption respectively.