• Journal of Korean Society of Environmental Engineers
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• v.22 no.11
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• pp.1985-1994
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• 2000

This research was designed to investigate the effect of initial adsorbed amount of phenol, temperature, and pH on the desorption reaction of phenol from spent activated carbon loaded with phenol. Methanol, acetone, and N,N-dimethylformamide( DMF) were used as test organic solvents. The initial adsorbed quantities of phenol investigated here were 166.1mg/g, 180.7mg/g, and 197.9mg/g. The effect of temperature was evaluated from 15 to $55^{\circ}C$ with an interval of $10^{\circ}C$, while that of pH was investigated under acidic. neutral. and alkaline conditions. The extent of phenol desorption was proportional to the strength of dipole moment such as methanol < acetone < DMF. Over 90% desorption of phenol was achieved by acetone and DMF. The quantity of des orbed phenol by the organic solvents decreases with increasing the initial adsorbed amount of phenol. DMF is affected least by the initially adsorbed amount of phenol. An increase in reaction temperature leads to higher desorption of phenol. Desorption reaction by methanol is most sensitive to the temperature. As the pH of solvents increases. the desorption rate is also increasing. At pH=12. the desorption rate of phenol by methanol increases sharply by 10%. Although methanol demonstrated the weakest desorption power. the desorption capacity of methanol would approach that of acetone and DMF by adjusting temperature and pH. Methanol may emerge as a promising solvent for removing phenol from activated carbon because of acceptable regeneration efficiency as well as relatively cheap price.

• Journal of Soil and Groundwater Environment
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• v.10 no.5
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• pp.45-51
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• 2005

The sorption/desorption characteristics of phenanthrene on the natural manganese oxide (NMD) were investigated in the presence of phenolic compounds. 4-chlorophenol (4-CP) was effectively oxidized by NMD catalyzed reaction and transformed into humic-like macromolecular compound through inter-or cross-coupling reaction between byproducts. As 4-CP was degraded with time, sorbed amount of phenanthrene on NMD was significantly increased, resulting from the formation of oxidative coupling products. These results imply that NMD can be used for simultaneous treatment of phenolic contaminants and polycyclic aromatic hydrocarbons (PAHs) in soils, sediments, or water. Also, sorbed phenanthrene on NMD in the presence of 4-CP showed high degree of desorption resistance, indicating that sequestration process of phenanthrene was ongoing with time.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.12
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• pp.2115-2123
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• 2000

This research was designed to investigate the mathematical model and kinetics of phenol desorption from spent activated carbon. elucidating the desorption characteristics of phenol in the case of using acetone. The Freundlich isotherm constant ($k_e$) is expressed as a function of temperature: $k_e(T)=0.1exp(797.297/T)$. The Freundlich isotherm constant(n) is a weak temperature function and is rarely affected by temperature below $50^{\circ}C$. whereas it is necessary to correct the n value with respect to temperature above $100^{\circ}C$ owing to significant deviation (~5%). Based on the assumption that the surface desorption reaction of phenol is rate limiting, the desorption model was developed. Desorption reaction constant($k_d$) was determined by means of fitting the theoretical results best to experimental ones. The Arrhenius relationships for $k_d$ was expressed by: $k_d(sec^{-1})=0.0479{\cdot}exp(-3037/T)$. The model was verified by comparing the experimental ones under different reaction conditions with the theoretical results determined by the previously estimated $k_d$. Since the difference between them is with 5%, it is expected that the desorption model of this research seems to be appropriate to explain the desorption of phenol from activated carbon by acetone. According to studies of the model. regeneration time and ratio was estimated as a function of temperature under present conditions as follows: (1) regeneration time : ${\tau}_{reg}(hr)=-0.08130T_c+8.4775$. (2) regeneration ratio : ${\eta}(%)=0.2210T_c+83.745$. The regeneration time at 15, 55, and $100^{\circ}C$. respectively. was 7, 4.2, and 0.35 hours, whereas the regeneration ratio was 87. 96. and 99%. respectively. Also. studies of the model would make it possible to determine the regeneration time and ratio under other specific conditions (temperature, applied acetone volume, amount of activated carbon, and initially adsorbed phenol amount).

• Analytical Science and Technology
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• v.7 no.1
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• pp.33-39
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• 1994

The purpose on this study was to develop a new improved chromatographic method for determination of trace phenols from environmental waste water. The research was carried out with selected 8 phenols, and solid-phase extraction was employed as sample pretreatment method. The coupling of XAD-4 and Dowex $1{\times}8$ resin as preconcentration column increased the selectivities toward interferences coexisted in matrix. Automation was accomplished with on-line process of pretreatment and HPLC system. After elution of sample through XAD-4 column, phenols were adsorbed by dispersion force, then displaced from it by ACN basified, simultaneously and selectively readsorbed via anion exchange on Dowex $1{\times}8$. Dowex $1{\times}8$ column was washed by water. Phenols readsorbed were removed from Dowex $1{\times}8$ column by a minimum volumn of methanol containing HCl. Each pretreatment step was connected by switching valves and the eluate was directly on-line injected to obtain fast and reliable results into the HPLC. Recovery of phenols was greater than 90%. To examine utility of this method, analysis of phenols from laboratory waste water sample which was added some organic pollutants to find with phenols on environmental waste water were also accomplished without their interference effects.

• Journal of Korean Society on Water Environment
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• v.27 no.3
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• pp.329-333
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• 2011

p-phenylene-2,5-benzobisoxazole (PBO; Zylon$(R)$) fibers as an adsorbent were employed for solid phase extraction of aqueous alkylphenols. The removal ratios for 10 kinds of alkylphenols at initial concentration of $100{\mu}gL^{-1}$ were in the range of 16.8-96.3% and the removals increased with the increase of the phase ratio (fiber weight/solution volume). The plots of the logarithm of partition coefficient (log K) were correlated with the logarithm of the n-octanol/water partition coefficient (log P). The adsorbed alkylphenols were completely desorbed with the mixture of acetonitrile and dichloromethane.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.89-89
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• 2019

수환경으로 유출되는 유해화학물질은 독성을 가지고 직접 유출되거나 다양한 매체와 반응하여 화재 및 폭발 등의 사고가 발생한다. 실제로 낙동강 유역에서는 1991년 페놀 유출사고를 시작으로 2009년 구미공단 '1,4-다이옥산' 유출사고, 2014년 11월 경북 봉화군의 황산유출사고 등 크고 작은 사고가 빈번히 발생하고 있으며 작년 6월에는 대구와 부산의 수돗물에서 과불화화합물이 검출되기도 하였다. 이러한 대규모 사고를 방지하기 위해 신속한 오염물의 거동 예측이 가능한 추적모델이 필요하며, 본 연구에서는 수환경으로 유출된 유해화학물질의 추적을 위한 1차원 저장대 모형을 개발하였다. 일반적으로 저장대 모형은 복잡한 하천 구조를 하천의 주 흐름이 존재하는 본류대와 하천 흐름이 정체되는 저장대, 그리고 하상구조로 단순화 하여 나타낸다. 본류대에서는 하천흐름에 의한 이송 및 횡방향 유속차로 발생하는 전단류에 의한 확산이 일어나며, 저장대와의 물질교환으로 발생하는 저장효과와, 하상구조와의 흡착 및 탈착, 그리고 생물화학적 반응 및 휘발이 발생한다고 가정한다. 본류대와 저장대간의 질량교환은 난류유속변동과 농도차에 의해서만 발생한다고 가정하고 오염물질의 이송과 분산과정을 해석한다. 저장대에서는 이송 및 전단류에 의한 확산은 일어나지 않으며, 본류대와의 물질교환으로 발생하는 저장효과와 하상구조로의 흡착, 그리고 생물화학적 반응 및 휘발이 발생한다고 가정하며, 하상구조에서는 본류대 및 저장대와의 흡착 및 탈착만 발생한다고 가정한다. 저장대 모형의 해석을 위해서는 리치(Reach) 별로 본류대 분산계수($K_F$), 본류대 면적($A_F$), 저장대 면적($A_S$), 그리고 저장대 교환계수(${\alpha}$)의 네 가지 저장대 매개변수가 필요하며 본 연구에서 개발된 저장대 모형은 흡탈착, 생물화학적 반응 및 휘발 과정을 모두 고려하여 유해화학물질의 확산 거동을 모의한다. 최적의 리치길이, 흡탈착, 반응 및 휘발 계수를 산정하여 모형의 정확도를 향상시켰으며, 신속하고 정확하게 오염물의 거동을 예측할 수 있었다.

• Geotechnical Engineering
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• v.11 no.4
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• pp.87-98
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• 1995

Laboratory tests were performed on modeling of in situ remediation of contaminated soils by aqueous solution extraction, thus investigating the feasibility of in situ treatments of soil to promote desorption of organic hazardous wastes. The investigation was conducted using phenol, aniline, quinoline, and 2-napthol adsorbed onto a UH40 soil, and various aqueous solutions were used to desorb, or otherwise remove, these organic contaminants. Decontaminants consisted of deionized water as a reference, hydrogen peroxide, acidy, bases, and surfactants. In situ conditions were modeled in the laboratory by permeating potential extracting liquids through reconstituted, contaminated soil specimens under controlled hydraulic gradients and stress condition through flexible wall permeameter tests. Sodium hydroxide desorbed phenol effectively. Aniline was effectively descorbed by nonionic surfactant. Anionic surfactant remediated quinoline and 2-napthol.

• Korean Chemical Engineering Research
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• v.49 no.2
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• pp.151-154
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• 2011

Catalytic activity such as conversion and selectivity on the phenol hydroxylation over TS-1 prepared by hydrothermal method and microwave heating method, respectively, was compared and discussed for understanding the dependence of solvent such as water, methanol, acetone, respectively, during phenol hydroxylation, with hydrogen peroxide. Basic physical properties such as XRD, EDS, SEM and $N_{2}$ adsorption/desorption were determined and compared. The relationship between catalytic activity and physical properties of TS-1 was explained.

• Korean Chemical Engineering Research
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• v.46 no.6
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• pp.1130-1134
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• 2008

Acetic acid has been used as a solvent in the process of manufacturing terephthalic acid. Although the used acetic acid has been mainly separated and recovered through the distillation process, adsorption process can be applied to recover a small amount of acetic acid remaining in the stream after the distillation process. In this study, activated carbon was selected as an adsorbent for acetic acid and the effects of temperature and acid treatment on adsorption capacity were investigated. The adsorption capacities of activated carbon for acetic acid were 0.176 mmol/g at 303 K and 0.118 mmol/g at 343 K, respectively. Adsorption capacity decreased with increasing temperature. The acid treatment of the activated carbon induced the increase in adsorption capacity, which was ascribed to increase in surface functional groups such as phenolic hydroxyl groups and carboxilic acid groups on the carbon surface. In the results of acetic acid desorption, 89% of adsorbed acetic acid was desorbed from activated carbon.

• Korean Chemical Engineering Research
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• v.48 no.6
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• pp.679-683
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• 2010

In this study, calcination temperature dependence of TS-1 catalyst was investigated in the hydroxylation of phenol with hydrogen peroxide during the regeneration of catalyst. Catalyst was regenerated 5 times by calcining at $550^{\circ}C$ and $700^{\circ}C$, respectively. When the catalyst was regenerated at $550^{\circ}C$ after 5th regeneration phenol conversion was decreased from 22.9% to 15.1% and at $700^{\circ}C$ after 5th regeneration phenol conversion was decreased from 22.9% to 18.8%. For formation ratio of catechol/hydroquinone was increased from 1.28 to 1.45 after 5th regeneration at $550^{\circ}C$, and from 1.28 to 1.20 after 5th regeneration at $700^{\circ}C$. The main reasons for deactivation of the catalyst were suggested by analyzing chemical/physical properties with XRD, UV-vis spectra, $N_2$ adsorption/desorption and TGA, and evaluating the catalytic activity such as phenol conversion and product selectivity.