• Biotechnology and Bioprocess Engineering:BBE
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• 제10권1호
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• pp.34-39
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• 2005

Trichloroethylene (TCE) is an environmental contaminant provoking genetic mutation and damages to liver and central nerve system even at low concentrations. A practical scheme is reported using toluene as a primary substrate to revitalize the biofilter column for an extended period of TCE degradation. The rate of trichloroethylene (TCE) degradation by Pseudomonas putida F1 at $25^{\circ}C$ decreased exponentially with time, without toluene feeding to a biofilter column ($11\;cm\;I.D.{\times}95\;cm$ height). The rate of decrease was 2.5 times faster at a TCE concentration of $970\;{\mu}g/L$ compared to a TCE concentration of $110\;{\mu}g/L$. The TCE itself was not toxic to the cells, but the metabolic intermediates of the TCE degradation were apparently responsible for the decrease in the TCE degradation rate. A short-term (2 h) supply of toluene ($2,200\;{\mu}g/L$) at an empty bed residence time (EBRT) of 6.4 min recovered the relative column activity by $43\%$ when the TCE removal efficiency at the time of toluene feeding was $58\%$. The recovery of the TCE removal efficiency increased at higher incoming toluene concentrations and longer toluene supply durations according to the Monod type of kinetic expressions. A longer duration ($1.4{\sim}2.4$ times) of toluene supply increased the recovery of the TCE removal efficiency by $20\%$ for the same toluene load.

• Korean Chemical Engineering Research
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• 제44권2호
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• pp.129-135
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• 2006

본 연구에서는 용매로써 sulfolane을 사용하고 2기의 증류탑을 이용하여 톨루엔이 과량 함유된 비 방향족 혼합물로부터 고 순도의 톨루엔을 생산해 내는 추출증류공정에 대한 전산모사 작업을 수행하였다. Sulfolane 용매를 이용한 추출증류공정의 모사를 위한 열역학 모델식으로는 NRTL 액체 활동도계수 모델식을 사용하였으며 범용성 화학공정 모사기인 Aspen Plus 12.1을 사용하였다. 모사 결과 최종제품으로 얻어진 톨루엔의 순도는 99.8 wt％였으며, 원료에 대한 회수율은 99.65％로 나타남을 알 수 있었다.

• 한국식품위생안전성학회지
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• 제14권1호
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• pp.76-83
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• 1999

Solid phase microextraction (SPME) was used for the determination of 6 standard solvents (methanol, isopropanol, methyl ethyl ketone, ethyl acetate, cyclohexane, toluene) in food packaging materials. SPME method is a solvent-free sample preparation technique in which a fused silica fiber coated with polymeric organic liquid is introduced into the headspace above the sample. SPME method using fiber coated polydimethylisiloxane (PDMS) was compared with static headspace (SHS) method used as a reference. It was found that the optimal adsorption condition using PDMS-SPME method was 2$0^{\circ}C$ for 15 minutes for the standard solvents. Detection limits, linearity, reproducibility and recovery of both SHS and PDMS-SPME methods have been determined using 6 standard solvents. Both methods were characterized by high reproducibility and good linearity. Using SHS methods, the mean recovery of the 6 standard solvents was ranged from 75.5% to 105.8% with a mean relative standard deviation (RSD) of 0.3% to 4.8%. With PDMS-SPME method, the mean recovery of the 6 standard solvents was ranged from 86.7% to 108.3% with a mean RSD of 0.4% to 2.5%. The detection limits of both methods were the same for toluene, cyclohexane and methyl ethyl ketone; those of PDMS-SPME method were higher than those of SHS method for methanol, isopropanol and ethyl acetate. PDMS-SPME fiber shoed excellent adsorption for non-polar solvents such as toluene, while it showed relatively low adsorption for polar solvents such as methanol.

• Korean Chemical Engineering Research
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• 제49권1호
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• pp.15-20
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• 2011

고분자전해질 연료전지에 유입되는 공기가 톨루엔에 오염되었을 때 전지 성능에 미치는 영향을 여러 톨루엔 농도와 운전 조건에서 연구하였다. 그리고 청정한 공기에 의한 전지 성능 회복과 활성탄 흡착에 의한 공기 중 톨루엔의 제거에 대해서도 연구하였다. 본 연구에서 실험한 톨루엔의 농도 범위는 0.1~5.0 ppm이었고 전지 성능감소와 회복은 일정전류에서 전압변화 측정법과 전기화학적 임피던스 측정법(EIS)에 의해 측정하였다. KOH 첨착활성탄의 톨루엔 흡착용량은 등온흡착곡선으로 구했다. 톨루엔 농도가 증가할수록, 전류밀도가 증가할수록, 공기유량이 증가할수록 톨루엔 오염에 의한 성능감소가 심했다. 그러나 상대습도가 증가할수록 톨루엔 오염에 의한 성능감소는 작았다. 가습된 청정 공기 중의 산소와 수분에 의한 톨루엔의 산화에 의해 전지의 성능이 회복되었다. 톨루엔의 백금 표면 흡착에 의한 전하 전달 저항 증가가 전지 성능을 주로 감소시킴을 EIS가 보였다. 첨착활성탄의 톨루엔 흡착 용량은 KOH 첨착량이 증가할수록 감소하였다.

• Bulletin of the Korean Chemical Society
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• 제22권9호
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• pp.953-957
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• 2001

The specificity of conjugation site for coating ligands was investigated using toluene-bovine serum albumin (BSA) conjugates in which BSA was conjugated at the position of o-, m-, and ${\rho}-toluic$ acid. Toluene-BSA conjugated at ${\rho}-position$ showed a binding activity of about 89-95%, whereas, those conjugated at o- and m-position of toluene exhibited a binding activity of 5 and 11%, respectively. On the basis of the above result, coating ligands with various proteins (OVA, BSA, KLH) were compared by conjugating with $\rho-toluic$ acid, and toluene-KLH was considered as the best coating ligand for this ELISA. Indirect competitive ELISA method was developed using anti-toluene antibody and $\rho-position$ conjugated toluene-KLH. The dose-response curve constructed after kinetic and optimization studies showed a 1${\times}$10-4 - 1${\times}$102 mM detectable response range with 0.1 ${\mu}M$ detectability. In specificity test of the antibody, the binding capabilities of aromatic compounds substituted with nitro-, alkyl-, chloro-, and hydroxyl group were larger rather than those of aromatic compounds (benzene, toluene and xylene) themselves. Also, tests with soil and water samples that had been spiked with toluene resulted in 102.7-113.7% recovery.

• 한국산업보건학회지
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• 제25권2호
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• pp.156-165
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• 2015

Objectives: The purpose of this study was to investigate the possible effects of a gasoline vapor recovery system on personal exposure levels of gasoline vapor constituents including benzene, toluene, ethyl benzene, xylene(BTEX), and methyl tert-butyl ether(MTBE) among gas station workers in a metropolitan area. Methods: Thirty-one gas station workers at ten gas stations in a metropolitan area were selected as subjects for this study. Test method PV2028 as recommended in the OSHA process was used for sampling and analysis. Results: The personal exposure levels of benzene, toluene, ethyl benzene, xylene, MTBE and gasoline vapor in the gas station workers were $0.0018{\pm}0.0069ppm$, $0.0077{\pm}0.0137ppm$, $0.0002{\pm}0.0008ppm$, $0.0016{\pm}0.0084ppm$, $0.2619{\pm}0.3340ppm$, and $1.4940{\pm}1.7984ppm$, respectively. After adjustment for refueling frequency and volume, personal exposure levelswere higher in the gas stations where gasoline vapor recovery systems(Stage II) were not installed, but the results were not statistically significant. Gasoline vapor concentrations showed a positive correlation to the level of MTBE, a gasoline additive. Conclusions: Vapor recovery systems(Stage II) were effective not only in reducing emissions of air pollutants, but also in reducing exposure to hazardous substances among gas station workers. In addition, acorrelation between gasoline vapors and MTBE concentration was confirmed.

• Korean Chemical Engineering Research
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• 제51권5호
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• pp.545-549
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• 2013

높은 수율로 CHMI를 제조하는 공정을 개발하기 위한 연구의 일환으로, 공정 중간체 CHMAIE를 합성하는 실험적 연구를 수행하였다. CHMAIE 제조 공정의 중간체인 CHMA 생성반응은 무수 말레인산 용액에 사이크로헥실아민을 점적 투입한 후 반응액을 2시간 동안 숙성시키는 방법으로 완료하였으며, 생성된 CHMA를 $10^{\circ}C$ 이하에서 2.5시간 동안 석출시키면 98.2%의 수율을 얻을 수 있었다. CHMA로부터 CHMAIE를 제조하는 에스테르화 반응의 최적 온도는 $68^{\circ}C$ 이었으며, 이 최적 온도에서의 평형 전화율은 98.5%였다. 에스테르화 반응이 평형에 도달하는 시간은 온도에 따라 감소하며, 최적 온도에서의 평형도달 시간은 약 3시간 정도였다. 최종 생성물 중의 톨루엔은 진공 증류를 통하여 회수할 수 있었다. 톨루엔의 회수율은 증류 온도가 증가함에 따라 증가하였고, 증류 온도 $55^{\circ}C$에서의 톨루엔 회수율은 98%였다.

• 한국환경과학회지
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• 제22권9호
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• pp.1131-1139
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• 2013

Desorption characteristics of VOCs were investigated for the effective recovery of gasoline vapor. The adsorption capacity and desorption capacity were excellent at relatively low temperatures. The differences in the desorption capacity were not large in the condition; desorption temperature $25^{\circ}C$, desorption pressure 760 mmHg, inlet air flow rate 0.5 L/min, but were relatively great in the condition; desorption temperature $0^{\circ}C$, desorption pressure 60 mmHg, inlet air flow rate 1.0 L/min. The desorption ability of pentane was increased to about 81.4%, and the desorption ability of hexane was increased to about 102%, also the desorption ability of toluene was increased to about 156.7% by changes of temperature, pressure, inlet air flow rate in the experimental conditions. The optimum desorption condition for the effective recovery of VOCs was in the conditions; desorption temperature $0^{\circ}C$, desorption pressure 60 mmHg, inlet air flow rate 1.0 L/min.

• Nuclear Engineering and Technology
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• 제53권11호
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• pp.3717-3722
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• 2021

In this study, the recovery rates of the dissolution method for radioactivity analysis of expandable polystyrene (EPS) with a liquid scintillation counter (LSC) using tetrahydrofuran (THF), toluene, and acetone as solvents were estimated. The detection efficiency calibration curve for each solvent was derived. Two methods-the volumetric ratio method and the quenching agent method-were used to prepare quench source sets, and calibration curves were derived by linking the data from the two quench source sets. The R² value of the calibration curve for THF was found to be 0.984. The relationship between the mass of dissolved EPS and the quench level was estimated: the quench level increased as the mass of dissolved EPS increased. Premix and postmix dissolution methods were tested. The recovery rates using THF with the premix method were 84.9 ± 0.9% and 96.5 ± 1.5% for ³H and ¹⁴C, respectively. Furthermore, the stability of the recovery rate over time when using THF was evaluated. The dissolution method with the premixed solution exhibited a more stable recovery rate over time. The dissolution methods were found to be applicable for analysis using LSC, and THF was found to be the most suitable solvent for the proposed method.

• 자원리싸이클링
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• 제8권3호
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• pp.31-36
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• 1999

아크릴로니트릴 제조공정 중 부산물로 생성되는 물과 아세토니트릴 공비혼합물을 분비, 회수하기 위하여 혼합용매로서 toluene-ethylacetate를 선택하여 $25^{\circ}C$에서 4성분계 toluene(1)-water(2)-acetonitrile(3)-ethylacetate(4)에 대한 액-액평형 데이터를 구하였다. Tie-line 계산치를 예측하기 위하여 실험치를 UNIFA 모델식의 파라미터와 상호연관시켜 비교하였다. 또한 용매의 성능을 비교하기 위하여 분배계수 및 선택도를 고찰하였다.