• Journal of Korean Society of Water and Wastewater
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• v.23 no.2
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• pp.175-180
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• 2009

This study was conducted to improve biological degradation efficiency of toluene as a model volatile organic compound (VOC) using yeast Candida tropicalis and to suggest an effective method for bioreactor operation. The yeast strain was immobilized with polyethylene glycol (PEG), alginate, and powdered activated carbon (PAC). The yeast-immobilized polymer media were used as fluidized materials in an airlift bioreactor. Polymer media without PAC were also made and operated in another airlift bioreactor. The two bioreactors showed toluene removal efficiencies ranging 80-96% at loading rates of $10-35 g/m^3-hr$, and the bioreactor containing the polymer media with PAC achieved higher removal efficiency. Protein contents in the liquid phase showed that the bioreactor using the yeast-immobilized polymer media with PAC had a higher rate of microbial growth initially than that without PAC. In addition, the microbial growth rate inside of the polymer media with PAC was five times higher than that without PAC. Consequently, the polymer media containing the yeast strain and PAC could enhance removal efficiencies for VOCs, and the immobilization method improve microbial activity and stability for a long-term operation of biological systems.

• Proceedings of the Membrane Society of Korea Conference
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• 1998.10a
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• pp.63-65
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• 1998

1. Introduction : Atmospheric discharge of VOC-contaminated streams in chemical plants and air streams from chemical processes poses a serious environmental problem and entails large financial losses. Such emissions may be reduced by i) adsorption process, ii) absorption process and iii) incineration process. These processes only forbids the air pollutions. Throughout the recent decade, another technique-membrane process has emerged. The separation and recovery of organic vapors by membrane process may have great economic potential. Most of the published research works on the separation of organic vapors from air were performed using silicon rubber membranes. However, it is very difficult to fabricate very thin membranes with less than 1 $u m thickness. Plasma polymerization could be a good technique to generate a thin polymer film. The objective of this work is to find out the optimum condition of plasma polymerization for producing VOC separation membrane. For the objective, composite membranes are prepared through plasma polymerization of hexamethyldisiloxane onto porous substrates under different conditions. The membrane is then subjected to the permeation of permanent gases and VOCs to find the correlations between the physical properties of the penetrant and permeability and selectivity.

• Analytical Science and Technology
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• v.20 no.1
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• pp.17-24
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• 2007

This study was performed to investigate the distributions of volatile organic compounds and carbonyl compounds at the 120 households in new apartments before occupation. The concentration of toluene, m, p-xylene, formaldehyde, acetone and ethylbenzene dominated as $272.81{\mu}g/m^3$, $98.90{\mu}g/m^3$, $71.68{\mu}g/m^3$, $70.58{\mu}g/m^3$ and $49.76{\mu}g/m^3$, respectively. The identified compounds by standards occupied 42.5% of the TVOCs, also the concentration of toluene occupied the largest part of the identified compounds as 18.5%. The concentration of formaldehyde and acetone were 43.1% and 42.4% among carbonyl compounds. The indoor/outdoor ratio of the concentration of benzene, toluene, formaldehyde and o-xylene were investigated 1.29, 3.59, 10.76 and 28.74, respectively.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.05b
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• pp.429-430
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• 2003

TiO$_2$를 이용한 휘발성 유기화합물(VOCs)의 광촉매적 제게에 관한 연구는 오염된 공기의 정화를 위한 대안적인 산화공정으로서 현재 많은 연구가 진행되어 오고 있다(A. J. Maira et al., 2001; Rosana M. Alberici and Wilson F. Jardim, 1997). 또한 가시광영역, 암반응 및 수분 등의 영향을 최소화하기 위해 금속 성분을 첨가하여 광촉매적 활성을 높이고자 여러 가지 시도들이 행해져 왔다(Akawat Sirisuk et al., 1999; John L. Falconer and Kimberley A. Magrini-Bair, 1998). (중략)

• Journal of Animal Science and Technology
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• v.63 no.4
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• pp.790-798
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• 2021

The objective of this study was evaluation of pig behavior changes related to temperature, relative humidity, volatile organic compounds (VOCs), and illuminance. A total of 24 growing pigs ([Yorkshire × Landrace] × Duroc) were used in the experiment. A sensor was installed at a height of 0.5 m in the center of the pig house. In experiment 1, temperature was changed every four days to 18℃ (T1), 22℃ (T2), 26℃ (T3), and then 30℃ (T4). In experiment 2, relative humidity was adjusted to 45% (low humidity [LH]), 60% (middle humidity [MH]), and then 75% (high humidity [HH]) for four days. In experiment 3, after cleaning the pig house just before experiment, only minimal ventilation was provided. VOCs and pig behaviors were observed for 7 days without cleaning the pig house. In experiment 4, three light bulbs of 40 W (470 lumens / 45 lx; low illuminance [LI]), 75 W (1,055 lumens / 103 lx; middle illuminance [MI]), and 100 W (1,521 lumens / 146 lx; high illuminance [HI]) were used for four days each. Pig behavior analysis was performed for following criteria : Feed intake, Standing, Lying, Sitting, Drink water, Rooting, Posture transition (lying-standing), Posture transition (standing-lying), Wallowing, and Biting. In experiment 1, feed intake time was lower (p < 0.05) for the T3 than other treatment groups. Standing time was highest (p < 0.05) for the T1 and lowest (p < 0.05) for the T3. Lying time was shorter (p < 0.05) in T1 and T2 compared to T3 and T4. Drinking frequency was higher (p < 0.05) for the T4 than other treatment groups. In experiment 2, the frequency of rooting and wallowing increased (p < 0.05) with increasing humidity. LH showed the lowest (p < 0.05) rooting frequency and HH showed the highest (p < 0.05) rooting frequency. In experiment 3, VOCs concentration did not (p > 0.05) change pig behavior. In experiment 4, lying time was the longest (p < 0.05) at LI and shortest (p < 0.05) at HI. Therefore, pig behavior is heavily influenced by the environment, especially temperature and humidity. However, correlation between pig behavior to VOCs and illuminance seems to be needed more research.

• Analytical Science and Technology
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• v.35 no.3
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• pp.116-123
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• 2022

Polymer bags, metallic canisters, and glass bottles have been used as containers for analyzing the volatile organic compounds (VOCs) in air. In this study, various sampling containers were compared to investigate the short-term stability of VOCs, that is, from the time they are sampled to the time they are analyzed. Polyvinyl fluoride (PVF), polypropylene (PP), polyester aluminum (PE-Al) bags, canisters, and glass bottles were used as sample containers. A 100 nmol/mol standard gas mixture of benzene, toluene, ethylbenzene, m-xylene, styrene, and o-xylene was used for the VOC comparison. Changes in the concentrations of samples stored for 10~20 day in each container were measured using a thermal desorption-gas chromatograph-flame ionization detector (TD-GC-FID). As a result, VOCs stored in a canister and two kinds of amber glass bottles have shown immaterial decreases in concentration in one week, and more than 80 % of the initial concentration was maintained for two weeks. In the case of polymer bags, the concentration of all VOCs, except benzene and toluene, were remarkably decreased below 70% of the initial concentration in one day. Particularly, ethylbenzene, xylene, and styrene have shown dramatic decreases in concentration below 30 % of the initial concentration in all polymer bags in one day.

• Membrane Journal
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• v.17 no.2
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• pp.99-111
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• 2007

It is impossible to remove toxic organic substances that are recognized as a cancer caused suspicious element in drinking water using the conventional water purification method. This study introduces groundwater into a reaction chamber as an effective amount of water to process this water using a mixed method of AOP oxidation and M/F membrane and purifies it as a desirable level by artificially mixing such toxic substances in order to effectively process the water. Based on this fact, this study configures an optimal operation condition. The VOCs existed in toxic substances was investigated as a term of phenol and toluene, and agricultural chemicals were also investigated as a term of parathion, diazinon and carbaryl. The experiment applied in this study was performed using a single and composite soolution. In the operation condition applied to fully dissolve and remove such substances, the amount of $H_2O_2$ injected in the process was 150 mL of a fixed quantity, the value of pH was configured as $5.5{\sim}6.0$, the temperature was controlled as a range of $12{\sim}16^{\circ}C$, the dissolved amount of ozone was applied more than 5.0 mg/L, the reaction time was determined as an optimal condition, such as $30{\sim}40$ minutes, and the segregation membrane in the same reactor was determined for acquire water drinking of large quantity using a pore size of $0.45{\mu}m$ M/F membrane.

• Analytical Science and Technology
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• v.23 no.5
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• pp.465-476
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• 2010

In this study, a number of volatile organic compounds (VOCs) including benzene, toluene, p-xylene, styrene, and methyl ethyl ketone were analyzed from samples collected in ambient air and under the field conditions. These samples were analyzed independently by two different set-ups for VOC analyses, i.e., between [1] gas chromatography/flame ionization detector with tube sampling - (F-T system) and [2] gas chromatography/mass spectrometer with bag sampling (M-B system). The analytical results derived by both systems showed fairly similar patterns in relative sense but with moderately large differences in absolute sense. The results of M-B system were high relative to F-T system with the F-T/M-B ratio below 1. If the relative biases of the two measurement techniques are derived in terms of percent difference (PD) in concentration values, the results were generally above 35% on average. A student t-test was applied to investigate the statistical significance of those differences between the systems. The results of both analytical systems were different at 95% confidence level for toluene, p-xylene, styrene, and methyl ethyl ketone (P < 0.043). However, F-T and M-B systems showed strong correlations for toluene and p-xylene. The observed bias is explained in large part by such factors as the differences in standard phases used for each system and the chemical loss inside the bag sampler.

• Elastomers and Composites
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• v.51 no.3
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• pp.226-232
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• 2016

We studied the photocatalytic functionality such as deodorant, antibacterial, fine dust collection efficiency of polyester-based non-woven fabric filter treated with self-actuated photocatalyst. According to UV/visible result, the UV-visible peak of visible-light responsive photocatalyst was found to be red shift at 420 nm sensitive in the visible light region. The deodorizing performance was shown to be reduced more than 80% even without dark conditions. Fine dust particles collection efficiency was shown to be excellent at the size of not only $2.5{\mu}m{\sim}10.0{\mu}m$ but also less than $2.5{\mu}m$. Also antimicrobial and antifungus was shown to be reduced more than 99.9%.

• 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.