• Journal of Microbiology and Biotechnology
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• v.13 no.2
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• pp.301-304
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• 2003

In this study, hydrogen sulfide ($H_2S$), ammonia ($NH_3$), and benzene, which represent the major odor from a natural leather process plant, were removed using a fluidized bed bioreactor and biofilter including Thiobacillus sp. IW and a MY microbial consortium. The critical removal rate was $12g m^{-3}h^{-1}\;for\;H_2S,\;11g m^{-3}h^{-1}\;for\;NH_3\;and\;28 g m^{-3}h^{-1}$ for benzene by the fluidized bed bioreactor, and $8.5g m^{-3}h^{-1}\;for\;H_2S\;7g m^{-3}h^{-1}\;for\;NH_3,\;and\;25 g m^{-3}h^{-1}$ for benzene in the biofilter. The average removal efficiency of $H_2S$, $NH_3$, and benzene by continuous operation for over 30 days with the fluidized bed bioreactor was $95{\pm}3\%,\;99{\pm}1\%,\;and\;98{\pm}5\%$, respectively, whereas that with the biofilter was $96{\pm}4\%,\;95{\pm}4\%,\;and\;97{\pm}3\%$, respectively. Therefore, the critical removal rate of $H_2S$, $NH_3$, and benzene was higher in the fluidized bed bioreactor, whereas the removal efficiency on the continuous operation was similar in both bioreactors.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.25 no.2
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• pp.146-155
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• 2015

Objectives: The aims of this study were to set up benzene exposure matrices according to industry and process and to assess the risk of those occupational exposure to benzene. Methods: The benzene exposure matrices were assembled depending on industry and process, based on an exposure database provided by KOSHA(the Korean Occupational Safety and Health Agency), which was gathered from a workplace hazards evaluation program in Korea. These exposure matrices were assessed by Hallmark Risk Assessment tool. Results: The benzene was treated 412 industries sector(36%), 2,747 business places, and 471 industrial processes according to database. The arithmetic mean of past decade 8 hours time-weighted average of airborne benzene concentrations in the workplace was 0.10722 ppm. 1.07% of the total sample were greater than OEL, and 59.8% were showed less than the limit of detection. The highest risk values(Danger Value) were seen 36 industries including manufacture of general paints and similar product and 12 processes, such as other painting of manufacture of metal fabricated members. Exposure matrices based on employee exposure data base may provide exposure histories and can be used in epidemiological studies. Conclusions: It was found that more attentions should be paid to 36 among 412 industries and 12 of 471 processes, with a higher risk value.

• Journal of the Korean Chemical Society
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• v.13 no.4
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• pp.273-280
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• 1969

The MO's of maleic anhydride are calculated using the parameter values, $h_{o}$.= 1, $h_{o}$:= 2, $k_{c=o}$= 1, $k_{c-o}$= 0.8, and ${\delta}_{{\alpha}_n}=2{\times}(0.3)^n$. With these MO's the interaction energies of the photochemical reaction of maleic anhydride (MA) with benzene are calculated using intermolecular orbital theory. It is shown that there are cases where the interaction energy includes a constant term and this term takes a great role in the photochemical interaction energy, and that with the calculated interaction energies the reaction mechanism is quite well explained. And it is proved that the photochemical reaction is possible for the second addition step of MA to benzene, and that the MA-benzene adduct should have the well-known stereochemical structure.

• Korean Journal of Agricultural Science
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• v.46 no.2
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• pp.257-271
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• 2019

The use of food grade hexane (FGH) for edible oil extraction is responsible for the presence of benzene in the crude oil. Benzene is a Group 1 carcinogen and could pose a serious threat to the health of consumer. However, its detection still depends on classical methods using chromatography which requires a rapid non-destructive detection method. Hence, the aim of this study was to investigate the feasibility of using Fourier transform infrared (FTIR) spectroscopy combined with multivariate analysis to detect and quantify the benzene residue in edible oil (sesame and cottonseed oil). Oil samples were adulterated with varying quantities of benzene, and their FTIR spectra were acquired with an attenuated total reflectance (ATR) method. Optimal variables for a partial least-squares regression (PLSR) model were selected using the variable importance in projection (VIP) and the selectivity ratio (SR) methods. The developed PLS models with whole variables and the VIP- and SR-selected variables were validated against an independent data set which resulted in $R^2$ values of 0.95, 0.96, and 0.95 and standard error of prediction (SEP) values of 38.5, 33.7, and 41.7 mg/L, respectively. The proposed technique of FTIR combined with multivariate analysis and variable selection methods can detect benzene residuals in edible oils with the advantages of being fast and simple and thus, can replace the conventional methods used for the same purpose.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.32 no.4
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• pp.340-349
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• 2022

Objectives: The importance of MSDS is emphasized for communicating hazardous information due to the increase in the types and usage of chemical substances. The purpose of this study is to assess the reliability of MSDS by collecting and examining paint thinners commercially available in South Korea. Methods: Twenty-five paint thinners were purchased at paint stores and the provision of MSDS was checked. Quantitative and qualitative analysis was performed on the chemical constituents of the thinners using GC-MSD and GC-FID. Reliability was evaluated by the MSDS collection rate for the paint thinners and calculating the rate of matching between laboratory analysis results and the contents and composition of chemical constituents given in the MSDS. Results: Unlike a study conducted in 2006, MSDS were provided for all 25 thinners. As a result of qualitative analysis using GC-MSD, 104 chemical substances were detected. The substances with the highest detection rate were identified in the order of toluene, butyl acetate, acetone, xylene, and ethyl benzene. A component matching rate of 41% was found by comparing the differences between the number of substances detected in laboratory testing and the number of substances listed in the MSDS. Benzene, a carcinogen not listed in the MSDS, was detected in two thinners produced by a small company. The detected benzene contents were 0.039 and 0.040%. When benzene is used, it should be strictly handled according to the Industrial Safety and Health Act. However, since it is not listed on the MSDS, it is judged that benzene was not being managed as a carcinogen in the workplaces where it is used. Conclusions: Since the reliability of MSDS, which play an important role in hazard communication, was evaluated to be low, it is necessary to systematically and continuously secure this reliability. In particular, carcinogens should be managed more strictly.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.33 no.4
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• pp.385-394
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• 2023

Objectives: Firefighters could be exposed to a range of toxic chemicals during firefighting. When tyre burns, various toxic chemicals including volatile organic compounds(VOCs) could be emitted. In this study, the researchers assessed the VOC exposure of firefighters during tyre fire suppression through biomonitoring. Methods: There was a big tyre fire on 12 March 2023. Of the responding firefighters, we recruited 14 participants to collect their urine after firefighting. One week later, researchers collected firefighters' urine again right after their off-duty period. We analyzed each metabolite of benzene, toluene, xylene, and styrene in urine and compared their exposure level based on sampling time. Results: The detection rate for metabolite of benzene, toluene, styrene, and xylene in urine sampled at each time was 43%-64%, 100%, 86%-100%, and 100%, respectively. Except for the benzene, metabolite levels measured in urine after firefighting were similar to that from off-duty period. However, the median concentration of benzene metabolite in urine sampled after firefighting was three times higher compared to that from off-duty period(34.2 ㎍/g crea. and 10.9 ㎍/g crea., respectively.) The estimated airborne concentration of benzene calculated from metabolite level in urine was 0.16 ppm, which exceeded the recommended exposure level set by the National Institute for Occupational Safety and Health. Conclusions: This study shows that firefighters could be exposed to the high level of VOCs including benzene during their firefighting especially at tyre fire. These results could be used as a valuable data to prove firefighters' exposure to hazardous chemicals during their duty.

• Bulletin of the Korean Chemical Society
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• v.25 no.2
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• pp.321-324
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• 2004

• Environmental Engineering Research
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• v.7 no.2
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• pp.85-92
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• 2002

• Bulletin of the Korean Chemical Society
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• v.22 no.9
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• pp.1056-1058
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• 2001

• Journal of Korean Society of Environmental Engineers
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• v.38 no.8
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• pp.435-443
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• 2016

In this study, MACT (Maximum Achievable Control Technology) application effect was evaluated for minimization of benzene fugitive emission in petrochemical industry. Although fugitive emission for benzene in the nation was regulated by the Clean Air Conservation Act from 2015, the US EPA already has introduced MACT standard to minimize its emission with up-to-date technology since 1995. EPA Emission Factor (AP-42) and EPA MACT Standard Guideline were used to assess MACT application effect. As a result, For MACT application it could reduce benzene emission up to 98% (average) comparing with uncontrolled facility, while the national regulation could achieve about 95% (average) reduction which is slightly lower than MACT. However there is no control measure in the national regulation to reduce benzene emission for vessel loading even though MACT standard requires preventive facility such as VRU (Vapor Recovery Unit). For further reduction of benzene emission, it needs to be mandatory for operation of VRU when benzene product is loaded in vessel. These efforts could contribute to achieve the global level for benzene emission management in national petrochemical industry.