This study aims to present safety distances by the damage impact assessment of the leakage of propylene oxide. As a result of the experiment, the pressure 1psi range was 52m to 169m, the radiant heat 18kW/㎡ range was 63m to 163m, the AEGL-2 range was analyzed as 224m to 414m, and the fire ball diameter was analyzed to be 45m to 121m. Additionally, the extent of damages was proportional to the amount of propylene oxide stored or handled. The safe distance for a 10% lethality due to overpressure and radiant heat was calculated to be 134m, and the safe distance for a 0% lethality was 169m. Toxicity was measured at 134m with a lethality 0%. Therefore, the safety distance due to leakage of propylene oxide is calculated to be between 134m and 169m.

This study tested the effect on the toxicity of formaldehyde to select a shelter site due to formaldehyde leakage. As a result of the experiment, the range of ERPG-2 and 3 is between 2.2km and 9.6km, ASET is 6 minutes at 1km, 15 minutes at 3km, 22 minutes at 5km, and the lethality rate is 99.9% at 1km and 9% at 3km. In areas where refuge time is less than 15 minutes or the lethality rate is more than 2%, a shelter is installed. This is because if there are only a few evacuees, the evacuation time may take longer than the pre-movement time of 15 minutes or less specified in PD 7974-6:2004, and the lethality rate with the lowest number of deaths was calculated to be 2%. The shelter must be equipped with a hepa-filter, positive pressure equipment, air purifier, air respirator, goggles, chemical protective clothing type 4 and sufficient parking space must be secured to ensure the safety of evacuees.

In this study, we examined the residual amounts of formaldehyde in hygiene products to determine the safety of these products in Gyeonggi-do. Formaldehyde is among the harmful substances that may remain within certain hygiene products. On the basis of an analysis of formaldehyde in a total of 222 items (6 disposable paper straws, 9 disposable paper napkins, 21 toilet papers, 13 disposable dishcloths, 16 disposable paper towels, 32 wet wipes for food service restaurants, 25 disposable cotton swabs, and 100 disposable diapers), we detected traces in three wet wipes for food service restaurants (1.87 to 4.45 mg/kg), which is approximately 9% to 22% of the standard level (20 mg/kg). We established that all the hygiene products assessed in the study met the individual standards for formaldehyde, thereby confirming that safe products are being distributed. In the standards and specifications for hygiene products, the formaldehyde test method is regulated for application with respect to three categories based on the type of product. The samples used in this study were of types for which method 1 or method 2 is applied, and the limits of detection, limits of quantification, linearity, and recovery rates were reviewed to verify the validity of each test method. When method 2 was applied, we experienced interference when performing analysis at a wavelength of 412 nm, which was associated with the influence of impurities in some samples of disposable cotton swabs and disposable diapers. Consequently, in these cases, the results were compared after analysis using method 1. By comparing the results obtained using method 2 with those obtained using method 1, the latter of which were unaffected by the interference of impurities, we were able to detect formaldehyde at low concentrations. These findings accordingly highlight the necessity to standardize the formaldehyde test method for future analyses.

This study evaluated how acid treatment affects the ability of customized beads of activated carbon (BAC) to remove formaldehyde from air. Two different acids (hydrofluoric acid and sulfuric acid) were used to modify the surface of BAC prepared from a polymer material. The acid-modified BACs were further subjected to heat treatment. Physical and chemical characteristics of modified and unmodified BACs were investigated using nitrogen adsorption, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray fluorescence, and X-ray photoelectron spectroscopy. Formaldehyde removal was evaluated under both dry and moist conditions. From the results, acid treatment clearly improved the adsorption performance, especially under the moist condition. Qualitative and quantitative surface analyses were conducted, mainly to examine the amount of O-bonds after acid treatment and the formation of S–O or Cl–O on BAC.

Vulnerable populations in healthcare facilities are more sensitive to exposure to indoor air pollutants, and therefore are more affected by such pollutants than the general population. This was the underlying reason why studies of indoor air pollutant concentration distribution and health risk assessment have been conducted targeting facilities, such as daycare centers, medical facilities, elderly care facilities, and postnatal care centers. However, previous studies have mainly focused on daycare and medical facilities for their research, and relatively speaking, studies conducted on the other venues are lacking. Therefore, this study aims to present the current status of indoor air quality and perform a health risk assessment in regard to Formaldehyde exposure at postnatal care centers and elderly care facilities. Here, the study focused on facilities that had undergone pollution level inspections from January 2017 to December 2021. A total of 81 postnatal care centers and 48 elderly care facilities were selected as the subject of the study. Then, the study utilized concentrations of five elements (CO2, HCHO, PM10, PM2.5, TBC) to determine the status of indoor air quality of both postnatal care centers and elderly care facilities. For health risk assessment, HCHO concentration was used. The investigation demonstrated that the yearly average concentration of the five elements stood within the indoor air quality maintenance standards, and the ratio of PM2.5 to PM10 in the two types of facilities was distributed as high as about 70%. In addition, the study showed that HCHO and TBC demonstrated a positive correlation when the relationship between indoor temperature and humidity with the five elements was examined. The health risk assessment showed that the cancer risk level of postnatal care center users stood below 10-6, below the level that is perceived as an acceptable risk. The cancer risk of workers from both postnatal care centers and elderly care facilities and elderly care facility users exceeded the acceptable risk level of 10-6, but was shown to be below 10-4, the maximum acceptable risk.

A conventional porous carbon is still a very promising material for the removal of gaseous pollutants because of its abundant surface functional groups and a high specific surface area. Here, we prepared an environment-friendly uniform N-rich narrow micropore activated carbon, for the removal of formaldehyde, based on steam activation and N-rich with chitin as the starting material. A sample carbonized at 500 °C and steam activated at 800 °C (CAC800) showed a reasonable yield (55%) with uniform and narrow micropores without mesopores but having a balanced nitrogen functionality. CAC800 possesses outstanding formaldehyde removal capabilities under both dry and wet (humidity 45%) conditions. In addition, when compared with commercial activated carbon materials, we clearly demonstrated that the existence of high nitrogen content with uniform and narrow micropores simultaneously removed formaldehyde, effectively.

In this work, the sulfonic acid group was introduced into the resorcinol–formaldehyde (RF) microspheres by the addition of p-phenolsulfonic acid during the polycondensation process of RF. The hydrophilicity of the sulfonated RF allowed KOH to infiltrate inside the microspheres, which enhanced the formation of mesopores in the carbon microspheres during the activation process by KOH. SEM and TEM observations and N2 adsorption measurements verified the formation of abundant mesopores in the porous carbon microspheres. The BET surface area of these mesoporous carbons exceeded 2000 m2/ g. In 17 m NaClO4 “water-in-salt” (WIS) electrolyte-based supercapacitor, the synthesized mesoporous carbon exhibited high specific capacitance of 170 F/g at current density of 0.5 A/g, comparable to those in regular KOH electrolyte. When graphite was used as current collectors, the symmetric cell could operate at 2.5 V, and the mesoporous carbon exhibited an energy density of 43 Wh/kg at power density of 0.25 kW/kg, and 25 Wh/kg at power density of 6.25 kW/kg, respectively, which were superior to those using Pt or stainless steel as current collectors. The mesoporous carbon/graphite was an excellent electrode in new-generation “WIS” electrolyte-based high-voltage supercapacitor due to their high energy and power density.

Recently, there has been growing interest in harmful substances released from household items such as volatile organic compounds (VOCs) and this has increased people’s environmental awareness. In this study, adhesives and manicures were used as samples of indoor household goods and formaldehyde emission and tested over time under temperature conditions of 15oC, 25oC, 35oC, and 45oC. The small chamber method as the indoor air quality process test method was employed and used to evaluate the concentration of formaldehyde emissions. As a result, formaldehyde emissions gradually decreased over time in both tests using adhesives and manicures. The cumulative emission showed a logarithmic function over time, and the formaldehyde can be released for longer periods of time at lower temperature conditions. The logarithmic value and response time showed linear relationships, and it can be inferred that the formaldehyde was released from the sample through the first order reaction. Furthermore, the relationship between temperature and velocity constants which was determined using the Arenius linear equation showed that the reaction rate of formaldehyde can be estimated by a temperature change.

위생용품의 기준 및 규격서에는 포름알데히드 함량 시 험법이 위생용품 유형별로 다르게 규정되어 있다. 위생용품 유형별로 미용티슈, 기저귀 안감 및 방수층, 팬티라이너를 대표 시료로 하여, 2,4-DNPH/HPLC법, 아세틸아세톤 /분광광도계법, 아세틸아세톤/HPLC법을 비교 분석하였다. 시험방법의 유효성 확인을 위하여 위생용품 유형별로 직선성과 검출한계, 정량한계, 회수율, 반복성 등을 검토하였다. 포름알데히드 표준용액으로 검량선을 작성 한 결과 3가지 시험방법에서 모두 상관계수(R2)가 0.999이상이었고, 검출한계와 정량한계는 위생용품의 기준 및 규격에 규정 된 각각의 최대잔류허용기준(Maximum Residue Level, MRL)에 비해 매우 낮게 나타났다. 또한 80%이상의 양호한 회수율을 확인할 수 있었고, 반복성(repeatability)도 20% 이내에 해당하여 양호하였다. 분석장비 별 비교에서는 분광광도계에 비하여 HPLC는 낮은 검출한계 및 정량한계 를 나타내어 정밀한 것으로 나타났다. 또한 유도체화 후 차광을 유지하면서 분석이 가능한 장점이 있었다. 유도체화 시액별 시간 경과에 따른 포름알데히드 안정성 평가를 위하여 2,4-DNPH와 아세틸아세톤으로 유도체화 한 후 0, 3, 6, 9, 24, 48 시간에 HPLC로 포름알데히드를 분석하였다. 2,4-DNPH로 유도체화 된 포름알데히드의 경우 시간의 경과에 따른 포름알데히드 피크면적의 통계적 유의성 은 보이지 않았다(P>0.05). 반면, 아세틸아세톤의 경우 유 의적인 상관관계를 보였는데(P<0.01), 아세틸아세톤-포름 알데히드 면적과 시간과는 음의 상관계수(r)를 보였다. 최초로 측정된 포름알데히드 피크면적평균 대비 시간대 별 피크면적평균 비교에서는 2,4-DNPH 시액으로 유도체화 한 경우에는 면적비의 특별한 증감이 관찰되지 않아 안정한 것으로 나타났다. 그러나 아세틸아세톤으로 유도체화 한 경우에는 시간의 경과에 따라 감소 경향을 보이다가 48시간 경과 후에는 81.3-95.2% 수준으로 감소하는 것으로 나타났다. 위생용품은 대부분 일회용으로 제조가 용이한 종이와 부직포 재질로 만드는 경우가 많고, 제조과정 중 접착제를 사용한다. 따라서 위생용품 최종제품에도 포름알데히드가 잔존할 가능성이 있다. 우리나라에서도 위생용품관리법으로 위생용품 중의 포름알데히드 기준을 마련하여 관리하고 있으나 시행 초기로 국내 유통 제품에 대한 포름알데히드 잔류 실태조사는 미흡한 실정이다. 이에 본 연구에서는 부산지역에서 유통 중인 위생용품 총 205건을 대상으로 포름알데히드 함량 모니터링을 실시하였다. 일회용 기저귀 74건 중 73건에서 0.13-29.87 mg/kg 의 수준으로 낮은 농도의 포름알데히드가 잔류되어 있음 을 확인하였다. 이에 일회용 기저귀는 피부에 직접 접촉 하는 부분을 중심으로 지속적인 관리가 필요할 것으로 생각된다. 반면 화장지 78건, 일회용 타월 27건, 일회용 행주 12건, 종이컵 7건, 일회용 종이냅킨 6건, 종이빨대 1건 에서는 포름알데히드가 모두 검출되지 않아 안전하게 관리되고 있음을 알 수 있었다.

The present work is aimed at evaluating the kinetics and dynamic adsorption of methylene blue by CO2- activated carbon gels. The carbon gels were characterized by textural properties, thermal degradation and surface chemistry. The result shows that the carbon gels are highly microporous with surface area of 514 m2/g and 745 m2/g for resorcinol-to-catalyst ratios of 1000 (AC1) and 2000 (AC2), respectively. The kinetics data could be described by pseudo-first-order model, with a longer duration to attain equilibrium due to restricted pore diffusion as concentration increases. Also, AC1 exhibits insignificant kinetics with fluctuating adsorption with time at concentrations of 20 and 25 mg/L. However, AC1 reveals a better performance than AC2 in dynamic adsorption due to concentration gradient for molecules diffusion to active sites. The applicability of Yoon–Nelson and Thomas models indicates that the dynamic adsorption is controlled by external and internal diffusion.

본 연구는 스파티필름의 수분 스트레스 정도에 따라 실내 공간 내 오염물질 제거 효율을 구명하고자 수행하였다. 식물이 없는 공간을 대조구, 정상적인 스파티필름과 수분 스트레스를 받은 스파티필름을 각각의 처리구로 하였다. 스파티필름의 수분 스트레스 유무에 따른 chamber 내 온도를 조사한 결과 대조구와 처리구 모두 식물의 생육 적정 범위인 23±1℃를 유지하였으며, 처리 간의 0.7℃의 차이를 보였다. 습도의 경우 대조구와 처리구는 유의차 있게 나타났으며, 처리 간의 유의 차는 없는 것으로 나타났다. 수분 스트레스에 따른 실내 오염 물질을 조사한 결과, 포름알데히드(Formaldehyde) 경우 대조구는 0.30mg･m-3, 정상적인 스파티필름은 0.05mg･m-3 , 수분 스트레스를 받은 스파티필름은 0.09mg･m-3으로 대조구와 처리구는 통계적으로 유의차를 보였으며, 식물 내 수분 스트레스에 따른 처리구간에는 유의차가 없었다. TVOC(Total Volatile Organic Compound)조사 결과, 정상적인 스파티필름의 TVOC는 5시간 후 0.00mg･m-3 으로 모두 제거 된 반면, 수분 스트레스를 받은 스파티필름은 0.34mg･m-3으로 다소 남아 있었으며, 대조구는 1.25mg･m-3으로 세 처리 모두 통계적으로 유의차 있게 나타났다. 또한 이산화탄소 변화량 조사결과, 대조구는 459ppm, 정상 스파티필름은 446ppm으로 통계적으로 유의한 차이는 없으며, 수분 스트레스를 받은 스파티 필름이 대조구보다 이산화탄소 함량이 다소 높았다. 기공변화율 조사 결과, 정상 스파티필름의 변화율은 높게 나타났으며, 수분 스트레스를 받은 스파티필름은 변화율이 낮은 것으로 조사되었다. 따라서, 스파티필름이 배치되어있지 않은 공간보다 배치된 공간이 공기정화에 효과적이며, 수분 스트레스를 받은 스파티필름은 실내오염물질 제거에 있어서 기공 변화율 및 이산화탄소 흡수능력이 저하되므로 스파티필름을 이용하여 효과적으로 실내오염물질을 제거하기 위해서는 적절한 수분 관리가 필요한 것으로 판단된다.

In order to protect the health of students and to prevent environmental harm, the School Health Law has been enacted and enforced. In the current “School Health Law Enforcement Rule”, school facilities, such as student desks and chairs, are required to use a small amount of formaldehyde emission values. In this study, an analysis was conducted with the purpose of using the basic data for the adjustment of the present emission standard. The formaldehyde exposure trend in the classroom was evaluated by examining the newly purchased student desks and chairs. As a result of measuring the compound levels in ten schools, the new student desks and chairs seemed to have contributed little to indoor formaldehyde levels. Only one classroom out of ten schools exceeded the threshold of 100 μg/m³ in Class 2 (without new desks and chairs) [(2)103.7 μg/m³]. A measurement of the classrooms exposed to formaldehyde for more than 10 years did not exceed the standard value. It is also very likely to be a source of contamination due to the recent construction (within 6 months) of indoor building materials, which was the dominant feature of the nine new schools. Although the study comprised a limited measurement, the appraisal results are suitable for HCHO emission.

This study measured concentrations of formaldehyde, a pollutant in the indoor air in three departments, before and after the renovation of a medical facility used by the general public, and conducted a health survey on workers' subjective symptoms. The average concentration of formaldehyde was 25.8 ± 8.7 μg/m3 before the renovation and 47.3 ± 6.7 μg/m3 after the renovation. The concentration was increased; however, it did not exceed the maintenance standard set by the law. Measured concentration was high both before and after the renovation in the office, and the biggest difference was shown in the concentration change. For eight symptoms including dry throat, there were more workers who expressed the symptoms after the renovation than those who expressed them before the renovation. Factors that influenced subjective symptoms were the effects before and after the renovation. Even when formaldehyde does not exceed the maintenance standard set by the law, detailed and systematic management is required and adequate health effect evaluation or education is necessary, considering the characteristics of medical facilities.

Microstructure evolutions of thermosetting resin coating layers fabricated by electrostatic spray deposition (ESD) at various processing conditions were investigated. Two different typical polymer systems, a thermosetting phenol-formaldehyde resin and a thermoplastic polyvinylpyrrolidone (PVP), were employed for a comparative study. Precursor solutions of the phenol-formaldehyde resin and of the PVP were electro-sprayed on heated silicon substrates. Fundamental differences in the thermomechanical properties of the polymers resulted in distinct ways of microstructure evolution of the electro-sprayed polymer films. For the thermosetting polymer, phenol-formaldehyde resin, vertically aligned micro-rod structures developed when it was deposited by ESD under controlled processing conditions. Through extensive microstructure and thermal analyses, it was found that the vertically aligned micro-rod structures of phenol-formaldehyde resin were formed as a result of the rheological behavior of the thermosetting phenol-formaldehyde resin and the preferential landing phenomenon of the ESD method.

The potential use of UV-TiO2 photocatalytic oxidation absorbent reactor in the removal of gaseous formaldehyde was studied. This study was conducted inside a bench-type circulation reactor chamber at ambient air conditions. PCO (Photocatalytic Oxidaion) degradation test for formaldehyde was done repeatedly and the average was reported. It was evident that photocatalytic oxidation was proven to be an effective method to control indoor air pollutants, like formaldehyde in indoor air. However, by-products are produced in the case of formaldehyde degradation also CO2, CO, H2O and formic acid are produced. These by-products can inhibit the active site of the photocatalyst. Thus, addition of adsorbent succeeding the PCO-TiO2, acts as a secondary treatment wherein produced by-products from the degradation and unreacted HCHO will adhere to the surface of the adsorbent. In this study, synthetic zeolite and activated carbon pellets were used to control of by-products of formaldehyde. PCOTiO2 degradation alone achieves 86% for a period of 60 minutes. Addition of adsorbent improves the removal efficiency achieving 90% and 96% using activated carbon pellet and zeolite, respectively.

This study used transmission electron microscopy (TEM) to investigate the micro-morphological features of two formaldehyde to urea (F/U) mole ratio liquid urea-formaldehyde (UF) resins with three hardener levels as a function of the curing time. The micro-morphological features of the liquid UF resins were characterized after different curing times. As a result, the TEM examination revealed the presence of globular/nodular structures in both liquid UF resins, while spherical particles were only visible in the low F/U mole ratio resins. The high F/U mole ratio liquid UF resins also showed extensive particle coalescence after adding the hardener, along with the appearance of complex filamentous networks. When the resins were cured with a higher amount of hardener and longer curing time, the spherical particles disappeared. For the low mole UF resins, the particles tended to coalesce with a higher amount of hardener and longer curing time, although discrete spherical particles were still observed in some regions. This is the first report on the distinct features of the crystal structures in low F/U mole ratio UF resins cured with 5% hardener and after 0.5 h of curing time. In conclusion, the present results indicate that the crystal structures of low F/U mole ratio UF resins are formed during the curing process.