• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2001년도 추계학술발표회
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• pp.19-22
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• 2001

The effects of pH on the sequential sorption/desorption of chlorinated phenols (2-chlorophenol, 2.4-dichlorophenol and 2,4,5-trichlorophenol) in HDTMA-montmorillonite were investigated by maintaining pH 4.85 or 9.15 in the sequential batch sorption and desorption experiments. The chlorinated phenols are hydrophobic ionizable orginic compounds; they can exist as either neutral (pH << pKa) or anionic (pH >> pKa) forms. Among the tested chlorinated phenols, 2,4,5-trichlorophenol showed the highest sorption affinity at pH 4.85 as expected by the $K_{ow}$ . Neutral speciation at pH 4.85 exhibited higher sorption affinity than anionic speciation at pH 9.15. Our results indicates that desorption of chlorinated phenols is strongly dependent on pH of the aqueous phase. Freundlich model was used to analyze the single-solute sorption/desorption results. The ideal adsorbed solution theory(IAST) was employed to predict the hi-solute sorption/desorption equilibria.

• 한국산업보건학회지
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• 제24권3호
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• pp.353-358
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• 2014

Purpose: This study was conducted to evaluate desorption efficiency and storage stability on activated carbon acquired form domestic market. Materials: Mixture of acetone, benzene, normal hexane and toluene was injected on four types of charcoal 100 mg. After overnight, charcoal was desorbed by carbon disulfide $1m{\ell}$ and analyzed by gas chromatography with flame ionization detector. Results: Desorption efficiency of benzene, normal hexane and toluene in charcoal tubes were 95% ~ 105%. But desorption efficiency of acetone in charcoal tubes was below 75% and different from types of charcoal. The more injected amount of acetone on charcoal showed higher desorption efficiency. Acetone injected on charcoal tubes migrated from front section into back section after 10 days storage at room temperature. Conclusions: Desorption efficiency and storage stability of activated carbon acquired from domestic market was good for benzene, normal hexane and toluene. The activated carbon acquired from domestic market has ability to be used as sampling media.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.249-249
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• 2012

The interaction of hydrogen with ZnO single crystal surfaces, ZnO(0001) and ZnO(000-1), has been investigated using a temperature programmed desorption (TPD) technique. Both surfaces do not interact with molecular hydrogen. When the ZnO(0001) is exposed to atomic hydrogen at 370 K, hydrogen is adsorbed in the surface and desorption takes place at around 460 K and 700 K. In ZnO(000-1), the desorption peaks are observed at around 440 K and 540 K. In both surfaces, as the atomic hydrogen exposure is further increased, the intensity of the low-temperature peak reaches maximum but the intensity of the high-temperature peak keeps increasing. In ZnO(000-1), the existence of hydrogen bonding to the surface O atoms and the bulk hydrogen has been confirmed by using X-ray photoelectron spectroscopy (XPS). When the Zn(0001) surface is exposed to atomic hydrogen at around 200 K, a new $H_2$ desorption peak has been observed at around 250 K. The intensity of the desorption feature at 250 K is much greater than that of the desorption feature at 460 K. This low-temperature desorption feature indicates hydrogen is bonded to surface Zn atoms. We will report the effect of the ZnO structure on the adsorption and bulk diffusion of hydrogen.

• Bulletin of the Korean Chemical Society
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• 제30권6호
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• pp.1349-1352
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• 2009

We report the results of the surface chemistry of deuterized ethanol exposed Zircaloy-4 (Zry-4) surfaces with various amount of $C_2D_5$OD exposures at 190 K. This system was examined with Auger electron spectroscopy (AES) and temperature programmed desorption (TPD) techniques. In TPD study, $D_2$ was evolved at two different desorption temperature regions accompanying with broad desorption background. The lower temperature feature at around 520 K showed first-order desorption kinetics. The high temperature desorption peak at around 650 K shifted to lower desorption temperature as the exposure of $C_2D_5$OD increased. The Zr(MNV) Auger peak shifted about 2.5 eV from 147 eV to lower electron energy followed by 300 L of $C_2D_5$OD dosing. This implies metallic zirconium was oxidized by deuterized ethanol adsorption. After stepwise annealing of the oxidized Zry-4 sample up to 843 K, the shifted Zr(MNV) peak was gradually shifted back to metallic zirconium peak position. After the sample was heated to 843 K, the oxygen content near the Zry-4 surface was recovered to clean surface level. The concentration of carbon, however, was not recovered by annealing the sample.

• 한국환경과학회지
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• 제11권3호
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• pp.227-234
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• 2002

Laboratory experiments were conducted to examine the behavior of metalaxyl in environment which was used as pesticide in green soil of golf course and as functions of the characteristics of adsorption, desorption and degradation in soil texture and organic matter contents. Acid water containing metalaxyl was conducted to evaluate the effects on adsorption, desorption and degradation. The adsorption of metalaxyl played more significant role in organic contents than clay contents, and pH Increases more pH 2.5 than pH 5.6. The desorption of metalaxyl from contaminants soil decreased higher organic contents LS-soil than S-soil, but the desorption amount of metalaxyl increased more pH 5.6 than pH 2.5. The rate of degradation of metalaxyl in green soil environmental increased higher organic contents LS-soil than S-soil and decreased more pH 2.5 than pH 5.6. These results indicated that the behavior of metalaxyl of the green soil was affected the soil texture of the golf course. Increasing of organic contents, the adsorption amount of metalaxyl on soil increased. Moreover the decrease of the pH of solution increased adsorption amounts and decreased desorption amounts. As the results, the transportation of metalaxyl in soil decreased the acidic rates. The acidification of soil by the acid rain increased the adsorption amount of metalaxyl, but the degradation of metalaxyl decreased. Therefore, it is possible to sustain contamination in run-off the stream and ground water by residuals in soil.

• 한국재료학회지
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• 제29권3호
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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.

• 한국산업융합학회 논문집
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• 제27권4_2호
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• pp.981-989
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• 2024

In recent years, there has been a growing focus on preserving the global environment and utilizing resources efficiently. The significance of energy conservation has led to the development of systems that recycle waste heat from factories and use eco-friendly refrigerants. This study aims to enhance the performance of adsorption-desorption systems using thermoelectric devices, which are known for their ability to convert temperature differences into electrical energy. The research focuses on improving the efficiency of these systems by integrating thermoelectric modules to cool the adsorption side and heat the desorption side, thus enhancing overall system performance. The experiments utilized a typical thermoelectric device and silica gel as the adsorbent. Key experimental parameters included varying the inlet air temperature and relative humidity on the desorption side. The results indicated that increasing the relative humidity of the inlet air on the desorption side significantly enhanced the overall mass transfer coefficient while reducing the completion time of the process. Similarly, higher inlet air temperatures led to an increase in the mass transfer coefficient and a decrease in process completion time. These findings suggest that optimizing the operational conditions of thermoelectric devices can substantially improve the performance of adsorption-desorption systems, offering potential benefits for applications in ventilation systems and other related fields.

• 대한환경공학회지
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• 제22권11호
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• pp.1985-1994
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• 2000

본 연구는 페놀의 초기 홉착량, 온도, pH가 유기용매에 의한 페놀 탈착에 미치는 영향을 조사하기 위한 것으로 methanol, acetone, N,N-dimethylformamide(DMF)를 유기용매로 사용하였다. 초기 흡착량은 166.1mg/g, 180.7mg/g, 197.9mg/g의 세 경우, 온도는 $15{\sim}55^{\circ}C$까지 $10^{\circ}C$ 간격으로 다섯 온도 조건, pH는 산성, 중성, 염기성에서의 페놀 탈착율 변화를 살펴보았다. 페놀의 탈착은 용매의 극성 모멘트와 비례하여 methanol < acetone < DMF 순으로 나타났으며, acetone과 DMF의 경우에는 탈착율이 약 90% 정도로 유사하였다. 초기 흡착량이 증가할수록 용매에 의한 페놀 탈착율은 직선적으로 감소하였으며, DMF에 의한 탈착율 감소 정도가 가장 완만한 것으로 미루어 초기 흡착량이 DMF 탈착 성능에 미치는 영향이 가장 적은 것으로 나타났다. 온도가 높아질수록 페놀 탈착도 증가하였으며, methanol의 증가폭이 가장 큰 것으로 미루어 methanol에 의한 페놀 탈착반응이 온도에 가장 민감함을 알 수 있다. 용매 pH가 높아질수록 페놀 탈착율도 증가하였으며, 특히 methanol의 경우는 pH 12에서 페놀의 탈착율이 10% 이상 급격히 증가되었으며, 이는 methanol의 탈착 능력이 pH의 영향을 가장 많이 받는 것으로 추정된다. 세 용매 중에서 methanol의 페놀 탈착율이 가장 떨어졌으나, 온도와 pH를 조절하게 된다면 acetone, DMF와 유사한 탈착율을 보였으며, methanol이 가장 저렴하기 때문에 적정한 탈착 조건을 선정 적용한다면 경쟁력있는 재생 용매로서 가능성을 지니고 있다고 판단된다.

• 한국토양비료학회지
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• 제11권2호
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• pp.75-80
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• 1979

암모니움 탈착(脫着)을 16개(個) 토양에 대하여 $(NH_4)_2HPO_4$를 처리하여 0.01M $CaCl_2$로 7회(回) 연속침출(連續浸出)하여 검토하였다. 1. 탈착(脫着)은 2~4개의 속탈(速脫) 또는 완탈단계(緩脫段階)의 반복(反復)으로 진행(進行)된다. 2. 탈착단계(脫着段階)는 탈착량(脫着量)(y)과 침출회수(浸出回數)(x)간(間)에 log y=b-ax의 관계식(關係式)이 성립(成立)된다. 3. 탈착율(脫着率)(100${\times}$탈착량(脫着量)/흡착량(吸着量))은 15개(個) 토양평균이 65%였고 최고(最高)는 김천통(金泉統)의 87% 최소(最小)는 삼각통(三角統)의 32%였으며 이탄토(泥炭土)인 용호통(龍湖統)은 156%로 토양 ammonium 이 다량방출(多量放出)되었다. 4. 탈착률(脫着率)은 흡착량(吸着量)과 부(否)의 상관을 보이며 이 관계에서 토양은 세개의 계열(系列)로 분류(分類)되었다. 5. 탈착누적곡선(脫着累積曲線)은 최대치(最大値)에 접근(接近)하고 있으며 7회탈착(回脫着)으로 모든 토양이 최대치(最大値)에 접근(接近)하였다. 이때의 흡착량(吸着量)은 CEC의 502%(삼각통(三角統))에서 25%(김해통(金海統))의 범위(範圍)에 있었다. 6. 탈착량(脫着量) 또는 탈착률(脫着率)은 LAMA, (암모니움 Langmuir 최대흡착) CEC, 점토함량(粘土含量), 유효인산, 유기물함량등(有機物含量等)과 아무런 관계가 없었다. 7. 이상(以上)의 결과(結果)들은 ammonium의 흡착(吸着)과 탈착(脫着)에 있어 Fe, Al Si 등(等)의 관련성과 동반음(同伴陰) ion 흡탈착(吸脫着)이 관여함을 강하게 암시하는 것 같다.

• 한국산업보건학회지
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• 제5권1호
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• pp.104-118
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• 1995

This study was performed to evaluate factors affecting desorption of organic solvents collected on charcoal tube and to find out the optimum condition. Desorption efficiency for polar analytes was improved when several polar desorption solvents such as methanol, dimethylformamide(DMF), 2-(2-butoxyethoxy)ethanol were added to carbon disulfide($CS_2$). The best improvement was achieved when 10% dimethylformamide(DMF) in $CS_2$ was used as desorption solvent. During storage of polar analytes, recovery was greatly reduced. Especially, the recovery of cyclohexanone was decreased to 18.1 % after a month storage at $34^{\circ}C$. After two weeks storage, recovery of polar analytes was sharply decreased. Water adsorbed on charcoal interfered the recovery of polar analytes but didn't interfere that one of nonpolar solvent, toluene. When 10% DMF in $CS_2$ was used as desorption solvent, the effect of water on recovery was decreased, comparing with Desorption efficiency increased when analyte loading increased, and usage of 10% DMF in $CS_2$ decreased the loading effect. Increasing volume of desorption solvent was not effective to improve desorption efficiency of analytes when 10% DMF was used. Continuous shaking and sonication is not helpful to increase the desorption efficiency of analytes except cyclohexanone using 10% DMF. When silica gel used as adsorbent, methanol was better desorbent than dimethylsulfoxide. Analytes adsorbed on silica gel showed high recovery in low concentration and less affected by humidity. On the basis of this study, the following conclusions have been drawn. To improve the recovery of polar organic materials in air samples, it is necessary to analyze samples as soon as possible after they were collected. Otherwise, samples must be stored at low temperature. Using two components of desorption solvents, such as 10% DMF in $CS_2$, the effects of loading and humidity decreased for polar analytes such as methyl ethyl ketone and methyl isobutyl ketone. When work place has high humidity with low concentration of polar organic solvents, silica gel can be used as adsorbent, because it produces quantitative recovery for polar analytes at this condition. But it should be noted that high humidity makes breakthrough easy in silica gel samples.