• Journal of People, Plants, and Environment
• /
• v.24 no.6
• /
• pp.585-593
• /
• 2021

Background and objective: Illegal open-air incineration, which is criticized as a leading source of air pollutants among agricultural activities, currently requires constant effort and attention. Countries around the world have been undertaking studies on the emission of heavy metal substances in fine dust discharged during the incineration process. A precise analytical method is required to examine the harmful effects of particulate pollutants on the human body. Methods: In order to simulate open-air incineration, the infrastructure needed for incineration tests complying with the United States Environmental Protection Agency (EPA) Method 5G was built, and a large-area analysis was conducted on particulate pollutants through automated scanning electron microscopy (SEM)-energy-dispersive X-ray spectroscopy (EDS). For the test specimen, high-density polyethylene (HDPE) waste collected by the DangJin Office located in Choongcheongnam-do was used. To increase the identifiability of the analyzed particles, the incineration experiment was conducted in an incinerator three times after dividing the film waste into 200 g specimens. Results: Among the metal particulate matters detected in the HDPE waste incineration test, transition metals included C (20.8-37.1 wt%) and O (33.7-37.9 wt%). As for other chemical matters, the analysis showed that metal particulate matters such as metalloids, alkali metals, alkaline earth metals, and transition metals reacted to C and C-O. Si, a representative metalloid, was detected at 14.8-20.8 wt%, showing the highest weight ratio except for C and O. Conclusion: In this study, the detection of metal chemicals in incinerated particulate matters was effectively confirmed through SEM-EDS. The results of this study verified that HDPE waste adsorbs metal chemicals originating from soil due to its own properties and deterioration, and that when incinerated, it emits particulate matters containing transition metals and other metals that contribute to the excessive production and reduction of reactive oxygen species.

• Particle and aerosol research
• /
• v.18 no.3
• /
• pp.79-86
• /
• 2022

Many commercial air purifiers currently have deployed granular activated carbon (GAC) filters for removing volatile organic compounds in the indoor air. GACs are generally used to remove gaseous contaminants in the air through adsorption by the inner surfaces of pores. In addition, airborne particles can be also filtered by the surface adsorption of the GACs, which can improve the life-time of the particulate filters. In this study, the filtration efficiency of GACs to ultrafine particles through surface adsorption was investigated at different volume flow rates by deploying a continuous particle filtration system. The polydisperse sodium chloride (NaCl) particles were generated by a set of an atomizer and a diffusion dryer, and then mixed with particle-free air at different volume flow rates. The penetration of ultrafine particles and pressure drop for each experimental condition were measured to figure out the effect of the volume flow rate on the surface adsoprtion of the GACs to particles, ~ 2 mm. The particle filtration efficiency of the GACs decreased as the volume flow rate increased from 4 to 14 lpm. However, the 5 times thicker GAC filter layer decreased the penetration of ultraparticles than a preious study. The filtration efficiency of the single granule was also higher than the previous result in the literature with smaller granule filter materials.

• Analytical Science and Technology
• /
• v.19 no.6
• /
• pp.553-558
• /
• 2006

In this study, an attempt was made to measure uncertainties involved in the VOC analysis for the VOC working standards prepared by a dilution technique using Tedlar bags. For this purpose, VOC standard gases of benzene, toluene, xylene, and styrene were prepared at four different concentrations (4, 8, 20, and 40 ppb). These standard samples were then loaded on to the GC system equipped with air server/thermal desorption (AS/TD) system. Each of these four standard concentrations was analyzed individually to derive their respective calibration results. These calibration data sets were then compared across four different compounds. According to this comparison, differences in calibration patterns were moderately insignificant within the selected concentration range of 4~40 ppb. It was also observed that the loss of styrene standard was fairly high compared to other VOCs investigated simultaneously. The results of our study suggest that the analytical uncertainty associated with the preparation of VOC starndard gas using a dilution technique can be assessed in a fairly reasonable manner for samples with a narrow concentration range.

• Journal of the Korean Institute of Gas
• /
• v.27 no.3
• /
• pp.134-140
• /
• 2023

Activated carbon is a carbonaceous material mainly used as a gaseous or liquid adsorbent. As fire-related accidents occur consistently due to the accumulation of heat of adsorption and oxidation of volatile organic compounds, the explosive characteristics and thermal stability of powdered and granular activated carbon made from coal and coconut shells were evaluated. As a result of the particle size analysis, the powdered activated carbon was in the particle size range (0.4~3) ㎛, and thermal properties such as exothermic onset temperature and decomposition behavior were analyzed using a differential scanning calorimetry and a thermogravimetric analysis. As a result of the evaluation of the explosion hazards for dust, both coal-based and coconut-based powdered activated carbon are classified as St1 class with weak explosion, but this is a relative and does not mean that the explosion hazards is absolutely low. Therefore, it is necessary to establish countermeasures for reducing the damage.

• Journal of the Korean Society for Heat Treatment
• /
• v.37 no.2
• /
• pp.49-57
• /
• 2024

We investigated the changes in microstructure and surface roughness of the compound layer of GC250D gray cast iron, commonly used in brake discs, during gas nitriding. The gas atmosphere of the nitriding process was controlled with a hydrogen partial pressure of 49.5%, and the process was conducted at a nitriding temperature of 520℃ with various process times. As the nitriding process time of the GC250D material increased, both the depth of hardening and the thickness of the compound layer increased, with a maximum surface hardness of approximately 1265 HV_0.1 was measured. Additionally, the surface roughness increased with the process time. Phase analysis of the compound layer revealed an increase in the proportion of the γ' phase as the nitriding process time increased. Changes in the formation of the compound layer were observed depending on the orientation of graphite within the material, leading to the formation of wedges. Therefore, the increase in surface roughness appears to be attributed to the uneven compounds, the expansion of the compound layer and wedges formed on the surface during the nitriding process.

• Journal of The Korea Institute of Healthcare Architecture
• /
• v.30 no.3
• /
• pp.67-74
• /
• 2024

Purpose: The identification and quantification of indoor airborne contaminants, including bio-aerosols, particulates, and gaseous contaminants, are crucial for maintaining acceptable indoor air quality for hospital operating rooms (ORs). Laparoscopic surgery has become widely accepted for various surgical procedures due to its rapid recovery rate and the low risk associated with small incisions compared to conventional open surgery. The objective of this study is to investigate the indoor air quality in hospital ORs and to identify indoor airborne contaminants generated during laparoscopic surgery. Methods: Measurements of an indoor environment, including temperature, humidity and air quality, were performed in an OR before and during a laparoscopic surgery. Indoor airborne contaminants, including volatile organic compounds (VOCs), formaldehyde, carbon monoxide (CO), carbon dioxide (CO₂), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), suspended indoor particles, and airborne bacteria, were measured simultaneously. Results: The study determined that the concentrations of indoor air particles and airborne bacteria increased during the surgery but were within acceptable levels. However, the concentration of CO₂, reached a high level of 1,791 ppm due to the CO₂ gas required for maintaining the pneumoperitoneum during the surgery. Implications: The results emphasized the use of ventilation and filtration in a laparoscopic surgery room to lower the concentration of filterable and non-filterable contaminants.

• Asian Pacific Journal of Cancer Prevention
• /
• v.14 no.4
• /
• pp.2461-2476
• /
• 2013

To assess environmental contamination with carcinogens, carbonaceous compounds, water-soluble ionic species and trace gaseous species were identified and quantified every three hours for three days st three different atmospheric layer at the heart of chiang-Mai, bangkok and hat-Yai from December 2006 to February 2007. A DRI model 2001 Themal/Optical Carbon Analyzer with the IMPROVE thermal/optical reflectance (TOR) protocol was used to quantify the organic carbon(OC) and elemental carbon content in $PM_{10}$. Diurnal and vertical variability was also carefully investigated. In general, OC and EC contenttration shoeed the highest values at the monitoring period o 21.00-00.00 as consequences of human activities at night bazaar coupled with reduction of mixing layer, decreased wind speed and termination of photolysis nighttime. Morning peaks of carboaceous compounds were observed during the sampling period of 06:00 -09:00, emphasizing the main contribution of traffic emission in the three cities. The estimation of incremental lifetime partculate matter exposure (ILPE) raises concern of high risk of carbonaceous accumulation over workers and residents living close to the observatory sites. The average values of incremental lifrtime particulate matter exposure (ILPE) of total carbon at Baiyoke Suit Hotel and Baiyoke Sky Hotel are approsimately ten time shigher then those air sample collected at prince of songkla University Hat-Yai campus corpse incinerator and fish-can maufacturing factory but only slightly higher than those of rice straw burnig in Songkla province. This indicates a high risk of developing lung cancer and other respiratory diseases across workers and residents living in high buildings located in Pratunam area. Using knowledge of carbonaceous fractions in $PM_{10}$, one can estimate the gas-particle partitioning of polycyclic aromatic hydrocarbons (PAHs). Dachs-Eisenreich model highlights the crucial role of adsorption in gas-particle partitioning of low molecular weight PAHs, whereas both absorption and adsorption tend to account for gas-particle partitioning of high molecular weight PAHs in urban residential zones of Thailand. Interestingly, the absorption mode alone plays a minor role in gas-partcle partitiining of PAHs in Chiang-Mai, Bangkok and hat-Yai.

• Journal of Korea Soil Environment Society
• /
• v.2 no.1
• /
• pp.83-90
• /
• 1997

Aiming at the treatment of large volumes of gas with a low concentration of poorly water soluble VOC(Volatile Organic Compound), a new system is proposed: the combination absorption tower/bioreactor. In the scrubber part of the bioscrubbing system, the contaminating compounds are absorbed in a aqueous phase. The contaminated scrubbing liquid is transported to the bioreactor, where the compounds are biodegraded by aerobic microorganisms (mainly to carbon dioxide, water, and biomass). In this study, separation of a volatile organic compound(VOC) out of a waste gas stream has been carried out using a re-cyclable high boiling point extrant(HBE). The liquid stream containing a high boiling point entrant(HBE) scrubs the gas stream in a direct gas-liquid countercurrent contacting operation in a packed tower for the removal of said component from the gaseous stream. A packed-bed column using Pall Ring was set up in order to simulate practical conditions for the scrubbing tower. The liquid stream transported to the bioreactor is recovered and recycled to the scrubber. The model gas, which contained 400 mg/$\textrm{m}^3$ of toluene, at a rate of 100 L/min, flowed into the packed column where the scrubbing liquid trickled over the packing in countercurrent to the rising gas at 10~15L/min. The bioscrubber designed for large volume air streams containing VOCs showed removal efficiency up to 80% in an optimum operating conditions during the tests fer removing toluene from an air stream by scrubbing the air stream with HBE.

• Journal of the Korean earth science society
• /
• v.26 no.7
• /
• pp.668-673
• /
• 2005

To collect or transfer samples of gaseous pollutants, various types of tubing are used. Hence, to analyze the uncertainties associated with the use of tubings, a series of comparative test were designed and conducted using the RSC standards with different concentration ranges. For the purpose of this study, we prepared tubings made of six different types of material which include: [1] silco-steel (S1), [2] stainless steel (S2), [3] silicone (S3), [4] PTFE Teflon (T1), [5] tygon (T2), and [6] brass (B). The patterns of RSC loss on to tubing walls, when compared on the basis of the least reactive material S1, exhibited that the extent of RSC loss varied dynamically. It was found that Teflon is highly stable. However, other materials tend to exhibit contrasting patterns of loss. S2 and B show significant loss of light RSC $(H_2S\;and\;CH_3SH)$, while S3 and T2 experience notable loss of heavy RSC (DMS and DMDS).

• Journal of Environmental Impact Assessment
• /
• v.29 no.4
• /
• pp.286-297
• /
• 2020

This research studied human health risk assessment of PAHs (Polycyclic Aromatic Hydrocarbons) in road dust sediments collected from 6 sites in four different cities in Korea. PAHs are well known to be human carcinogens and toxic compounds that are commonly generated from incomplete combustion of fuels and energy products. Such compounds which is absorbed by atmospheric suspended dust can be emitted into air in gaseous form and often deposited on road dust sediments. The PAHs which is deposited on sediment particles can also be re-dispersed by vehicles or winds on the road surface. It can be harmful for humans when exposed via breathing, ingestion and dermal contact. This study examined human health risk assessment of PAHs in deposited road dust sediments. Results showed that the excess cancer risk estimates were above 1.0×10-6 at main traffic roads and resident area in Ulsan city. According to the result of deterministic risk assessment, dermal-contact was the major pathway, while the contribution of the risk from inhalation was less than 1%. The probabilistic risk assessment showed similar levels of cancer risk derived from the deterministic risk assessment. The result of sensitivity analysis reveal that exposure time is the most contributing factor (69%). Since the values of carcinogenic risk assessment were higher than 1.0 × 10^-6, further detailed monitoring and refined risk assessment for PAHs may be required to identify more reliable and potential cancer risks for those who live in the study locations in Ulsan city.