• Journal of odor and indoor environment
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• v.17 no.4
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• pp.396-403
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• 2018

In this study, volatile organic compounds (VOCs) emitted from printing industries were analyzed, and an inorganic adsorbent, ${\gamma}-alumina$, was selected for the effective control of the VOC emissions. Printing processes commonly require inks, thinners, and cleaners, and they were mixed organic solvents containing aromatic compounds, ketones, and alcohols. Therefore, toluene, methyl ethyl ketone (MEK), and isopropyl alcohol (IPA) were selected as model compounds for this study. The adsorptive properties using ${\gamma}-alumina$ were determined for the model compounds. Both batch isotherm and continuous flow column tests demonstrated that the adsorption capacity of MEK and IPA was 3~4 times higher than that of toluene. The column test performed at an inlet toluene concentration of 100 ppm showed that an 80% breakthrough for toluene was observed after 3 hours, but both MEK and IPA were continuously adsorbed during the same time period. A numerical model simulated that the ${\gamma}-alumina$ could remove toluene at a loading rate of 0.4 mg/min only for a 4-hour period, which might be too short of a duration for real applications. Consequently, lifetime enhancement for ${\gamma}-alumina$ must be implemented, and ozone oxidation and regeneration would be feasible options.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.7 no.1
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• pp.71-85
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• 1997

The purpose of this study was to evaluate concentrations of organic solvent mixtures in air of rotogravure printing workplaces. Qualitative and quantitative analysis of organic solvents contained in the gravure inks used at rotogravure factories had been done. The results obtained were as follows: 1. The gravure inks mainly consist of toluene, methyl ethyl ketone(MEK), and ethyl acetate(EA), and traces of isopropyl alcohol(IPA), xylene, 2-butanol, cyclohexane, cellosolve etc were also contained in them. 2. Thinner used as a diluent consist of toluene, MEK, and EA. 3. Geometric mean concentration of toluene in ambient air were 23.81 ppm at gravure printing of packing material, 42.10 ppm at gravure printing of wallpaper, 16.95 ppm at gravure printing of plastic bottle for beverage and 4.31 ppm at gravure printing of plywood printing or floor covering. Concentrations of toluene in ambient air showed statistically significant difference between types of printing. 4. Concentrations of MEK in ambient air were 12.43 ppm at gravure printing of packing material, 5.47 ppm at gravure printing of wallpaper, 16.78 ppm at gravure printing of plastic bottle for beverage and 16.44 ppm at gravure printing of plywood printing or floor covering. MEK concentrations in ambient air showed no significant difference. 5. Conentrations of EA were 14.30 ppm at gravure printing of packing material, 1.92 ppm at gravure printing of wallpaper and 21.12 ppm at gravure printing of plywood printing or floor covering. EA concentrations in ambient air shown significant difference. 6. Percentage of the workplaces where the ambient air concentration of organic solvent mixtures exceeded the Korean Permissble Exposure Level(KPEL) amounted to 18.03%. 7. Toluene concentrations in ambient air of rotogravure printing workplaces ranged from 0.69 to 156.02 ppm and urinary hippuric acid excretion ranged from 0.10 to $1.32g/{\ell}$.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.8
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• pp.747-753
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• 2010

This study was performed to investigate the removal characteristics of volatile organic compounds (VOCs) in the gasphase biofilters, and to propose a stoichiometric analysis approach to characterize biological reaction through carbon mass balance. The VOCs studied were toluene, styrene, methyl ethyl ketone (MEK), and methyl isobutyl ketone (MIBK) as a single substrate for each biofilter. The critical loading rate was determined to be $46.9\;g/m^3{\cdot}hr$, $25.8\;g/m^3{\cdot}hr$, $96.3\;g/m^3{\cdot}hr$, and $66.5\;g/m^3{\cdot}hr$ for toluene, styrene, MEK, and MIBK, respectively. The obtained results indicated that the critical loading rate was well correlated the octanol-water partition coefficient. In the analysis of carbon mass balance, carbon recovery to $CO_2$ became relatively lower as substrate loadings increased, but higher for carbon recovery to biomass. Stoichiometric analysis revealed that biomass yield increased as substrate loadings increased, and its coefficient (g biomass/g substrate) varied from 0.31 to 0.57 for toluene, 0.29 to 0.57 for styrene, 0.08 to 0.56 for MEK, and 0.14 to 0.53 for MIBK.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.7 no.1
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• pp.21-31
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• 1997

Toluene, n-hexane, and methyl ethyl ketone(MEK) were exposed to the activated carbon fiber(ACF) and 3M(Model 3500) diffusive samplers under low and high humidity levels. In order to evaluate these two samplers, the sampling capacity, sampling rate, reverse diffusion, and storage stability were obtained. At low humidity level($8{\pm}3%RH$), the adsorption amount of all three organic vapors to the ACF diffusive sampler showed a positive linear relationship up to 8 hours. However, at high humidity level($90{\pm}5%RH$), n-hexane and MEK maintained a positive linear relationship up to 1.5 hrs, but decreased in their adsorption amounts afterwards. On the other hand, the adsorption amount of n-hexane, MEK, and toluene to 3M diffusive sampler showed almost a positive linear relationship up to 8 hours at both humidity levels. At low humidity level, there was almost no reverse diffusion for both 3M and ACF diffusive samplers. However, when the ACF diffusive sampler was used at high humidity level, there was about 52.63% of MEK sample loss and about 92.59% of n-hexane sample loss. The storage stabilities of the ACF and 3M diffusive samplers were both relative stable except for MEK. In the case of MEK, the difference between the analysis of the organic vapor right after the sampling and that of 3 weeks later at room temperature was 45% for the ACF diffusive sampler and 18% for the 3M diffusive sampler. Since the storage stability of the samples stored in a refrigerator was relatively stable, they need to be refrigerated until the analysis is done.

• Toxicological Research
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• v.32 no.4
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• pp.337-343
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• 2016

We determined the toxicity of mixtures of ethyl acetate (EA), isopropyl alcohol (IPA), methyl ethyl ketone (MEK), toluene (TOL) and xylene (XYL) with half-maximal effective concentration ($EC_{50}$) values obtained using human hepatocytes cells. According to these data, quantitative property-activity relationships (QPAR) models were successfully proposed to predict the toxicity of mixtures by multiple linear regressions (MLR). The leave-one-out cross validation method was used to find the best subsets of descriptors in the learning methods. Significant differences in physico-chemical properties such as boiling point (BP), specific gravity (SG), Reid vapor pressure (rVP) and flash point (FP) were observed between the single substances and the mixtures. The $EC_{50}$ of the mixture of EA and IPA was significantly lower than that of contained TOL and XYL. The mixture toxicity was related to the mixing ratio of MEK, TOL and XYL (MLR equation $EC_{50}=3.3081-2.5018{\times}TOL-3.2595{\times}XYL-12.6596{\times}MEK{\times}XYL$), as well as to BP, SG, VP and FP (MLR equation $EC_{50}=1.3424+6.2250{\times}FP-7.1198{\times}SG{\times}FP-0.03013{\times}rVP{\times}FP$). These results suggest that QPAR-based models could accurately predict the toxicity of polar and nonpolar mixtures used in rotogravure printing industries.

• Applied Chemistry for Engineering
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• v.21 no.4
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• pp.430-434
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• 2010

The sheet for electromagenetic interference (EMI) shielding was prepared with slurry made by the mixture of binder, methyl ethyl ketone, cyclohexanone and metal powder. We tried to enhance the shielding efficiency by adding carbon nanotube (CNT), which has known as highly conducting material. Surface and component analyses were carried out with SEM and EDS, respectively. The electric characteristics and EMI shielding efficiencies were measured with 4-point probe measurement and EMI efficiency measurement equipment. The sheet with 2% CNT addition showed the lowest electrical resistance, $13.13{\Omega}}{\cdot}cm$. It also showed the highest EMI shielding efficiency of 63 dB.

• Journal of the Korean Society of Urban Environment
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• v.18 no.4
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• pp.503-509
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• 2018

In this study, a Proton-Transfer Reaction-Time-of-Flight Mass spectrometer (PTR-TOF-MS) was used for the continuous monitoring of Volatile Organic Compounds (VOCs) emitted from semiconductor workplace such as photolithography (PHOTO), flat panel display (FPD), organic light emitting diode (OLED), etching (WET) process. The averaged VOCs mixing ratio in the such workplace, PHOTO was 6.5 ppm, FPH was 6.4 ppm, WET was 2.0 ppm and OLED was 1.3 ppm, respectively. The abundance of VOCs in the workplace were methyl ethyl ketone (MEK) with 2.8 ppm (69%) and acetaldehyde with 0.5 ppm (13.2%). Depending on the semiconductor process characteristics, various VOCs have been observed in the workplace. The VOCs mixing ratio are lower than the workplace regulation standard (TWA), it is necessary to continuously monitor and effectively manage these VOCs.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.5 no.1
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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.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.12
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• pp.1209-1214
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• 2006

This paper presents an application of Dividing Wall Column(DWC) to the recovery of the waste solvent from the film making processes. The waste solvent feed contains MEK(Methyl-Ethyl-Ketone), Toluene, Cyclohexanone, and water. The commercial software $HYSYS^{TM}$ was used for rigorous simulation and analysis. Sensitivity analysis for several major design variables were carried out to achieve the optimal design of the process. Distribution of the internal vapor and liquid flows to the prefractionator and main sections is shown to be the most dominant design factor for energy saving efficiency in the DWC process. The simulation results also show that the solvent recovery process using the DWC significantly improves both the energy efficiency and the compactness of the solvent recovery process.

• Analytical Science and Technology
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• v.24 no.6
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• pp.493-502
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• 2011

The catalyst works for visible-light region was characterized. Toluene, xylene, MEK and ammonia were used as reactants. The decomposition efficiency was compared between visible-light photocatalyst and UV-light one. UV-photocatalyst can be activated with UV-light wave length of 280~360 nm. However, visible-light photocatalyst can be activated with visible wave length of 400~750 nm. This result was found by using UV-Vis absorbance. A lot of materials were doped to visible light photocatalyst in order to increase its performance. Platinum was added to visible light photocatalyst with manganese in order to increase performance of the visible light photocatalyst. MTMS (Methyl tri methoxy silane) was used as a binder. Contact angle was analyzed varying with amount of binder. Contact angle was increased with increasing the amount of MTMS. As a result, the hydrophilic property of photocatalyst with MTMS binder was decreased due to its hydrophobic one. And Mn-$TiO_2$ catalyst had an excellent anti-bacterial property.