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Effects of VOCs on Human Health

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... With the fast development of the economy, society, and industry in recent years, environmental pollution has become an increasingly serious issue, such as the emission of particulate matter (PM), automobile/industrial exhaust gas, industrial sewage, etc. [1][2][3][4][5] Particularly, volatile organic compounds (VOCs) exhibit the characteristics of a pungent odor, toxicity, and carcinogenicity, which will result in a severe threat to the ecological system and human health (Table 1) [6,7]. As shown in Figure 1, the emission of VOCs from China's petroleum industry increased by 24.08% from the year 2013 to 2019, which is much higher than that (4.07%) of the chemical industry [8,9]. ...
... Table 1. Effects of some VOCs on the environment and human health [7]. ...
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Volatile organic compounds (VOCs) are important precursors for the formation of secondary pollutants, such as fine particulate matter (PM) and ozone (O3), which will lead to severe atmospheric environmental problems to restrict the sustainable development of the social economy. Catalytic oxidation is a safe, eco-friendly, and simple method for eliminating VOCs, which can be converted into CO2 and H2O without the generation of other harmful substances. The fabrication and development of catalysts are very crucial to enhance the catalytic oxidation efficiency of the removal of VOCs. The noble metal catalyst is one of the commonly used catalysts for the catalytic oxidation of VOCs because of the high reaction activity, good stability, poisoning-resistant ability, and easy regeneration. In this review, the research progress of noble metal (Pt, Pd, Au, Ag, and Ir) catalysts for the removal of VOCs in recent years was summarized with the discussion of the influence factors in the preparation process on the catalytic performance. The reaction mechanisms of the removal of VOCs over the corresponding noble metal catalysts were also briefly discussed.
... VOCs are present in everyday life and play an important role in many natural and industrial processes: clear examples are ethanol, formaldehyde, isopropanol or acetone. Unfortunately, many of these compounds are dangerous to human health and associated with respiratory, allergic or immune responses and because of this great attention is given to them (Soni et al., 2018). As many other pollutants their effects are directly correlated with the extent and the intensity of the individual exposure and so the key point to prevent any harmful consequence is to be able to limit the exposure and protect users (Soni et al., 2018). ...
... Unfortunately, many of these compounds are dangerous to human health and associated with respiratory, allergic or immune responses and because of this great attention is given to them (Soni et al., 2018). As many other pollutants their effects are directly correlated with the extent and the intensity of the individual exposure and so the key point to prevent any harmful consequence is to be able to limit the exposure and protect users (Soni et al., 2018). A challenge of this kind is not trivial and, in any case and for any adopted solution, it is necessary to ensure that workers are exposed to chemical substances concentrations lower than the threshold limit value (TLV), the level to which an operator can be exposed day by day for a working life without harmful effects (Mills, 2016). ...
Chapter
In the last decade many different developments have taken place in the field of sensors driven by many new needs of the today world. In this context, gas sensors and volatile organic compounds sensors are for sure very interesting devices, thanks to the wide range of applications in which they can be employed. Smart, soft, highly sensitive systems are all examples of innovative typologies of instruments that can be fabricated working with proper formulated materials. In this work we are going to give an overview of the latest developed sensing materials that can be employed for volatile organic compound detection, focusing first of all on their synthesis and features and then going deeper in their engineering applications. All of the presented devices are analyzed from the perspective of their possible employment as end of service life indicator for respirator cartridges. This application, which represent a novelty in the field, would determine the possibility to monitor the service life of different personal protective equipment and would be a turning point for the workplace safety in various contexts.
... The use of these compounds and the alkaline medium (pH > 11) in degreaser formulations ensures high efficiency in removing grease, fats, and carbonized food-derived soils [3]. Nevertheless, some of these compounds create risks for human health and environmental pollution [4,5]. Therefore, the development of eco-friendly degreasers (without phosphates and pH < 11) is essential, while maintaining their cleaning efficiency. ...
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Detergent formulations for cleaning a carbonized soil—degreasers—typically comprise surfactants, organic solvents, phosphate-based cleaning agents, and alkaline agents, which results in high pH values (>11) that raise human and environmental risks. It is important to develop eco-friendly and safer degreasers, while maintaining their cleaning efficiency. In this work, simple degreaser formulations, with a pH below 11 and without phosphates, were developed by using a mixture of solvent, surfactant, and water to remove carbonized soil. The efficiency of the new degreaser formulations (with 5 wt% solvent, 5 wt% nonionic or ionic surfactant, and 90 wt% water) was evaluated by an abrasion test in the removal of carbonized soil from ceramic and stainless steel surfaces and compared with a commercial product. The results obtained show that the formulations comprising isopropylene glycol (IPG) with C11–C13 9EOs and diethylene glycol butyl ether (BDG) with octyltrimethylammonium octanoate ([N1118][C8O2]) present the best cleaning efficiency for both surfaces. The composition of these formulations was optimized for each surface using a mixture design. The resulting formulations, despite having a simpler composition, a pH lower than 11, and being phosphate-free, presented a cleaning efficiency equal or slightly higher than the commercial control. These results show that it is possible to design degreasers that are much less aggressive to the environment and user, while simultaneously fulfilling the market requirements.
... liver, nervous system, kidney), asthma, cancer, leukemia, and other deadly diseases are known as longterm effects of VOCs on human health. 2, 5 The presence of VOCs in the atmosphere is also dangerous to the environment. VOCs can give rise to global warming as most of them absorb the radiation in the infrared region. ...
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With industrial growth, air pollution has also increased. Air pollution is accountable for several diseases and numerous deaths. Volatile organic compounds (VOCs) are one of the most common classes of air pollutants and are mostly caused by anthropogenic activities. These VOCs have adverse effects on human health as well as on the environment. Photocatalytic oxidation is one of the most common methods available to get rid of VOCs. Photocatalytic oxidation (PCO) is usually performed under UV light, but various photocatalysts, which can work under the visible region of light (white light), have also been reported lately. Recently, PFOTES-CV-based visible light activated-superhydrophobic TiO 2 paints have been reported to have bactericidal activity according to the literature. In this study, we have used these TiO 2-based paints to study their photocatalytic efficiency against VOCs. The effects of multiple parameters including the input concentration of VOCs (2-5 ppm), amount of PFOTES (1-5%), light power source (8, 24 W), and humidity (60-70%) have been studied. Substantial photocatalytic efficiency was observed against toluene, p-xylene, and acetaldehyde. ∼92% against toluene, ∼99% against p-xylene, and considerable removal efficiency against acetaldehyde were found with the paint made with 3% PFOTES. Characterization of the photocatalysts was carried out by XPS, FTIR, and DRS. The PCO reactor under visible light was used for the photocatalytic decomposition reaction and the gas analysis was performed by GC/MS. Environmental signicance VOCs are one of the major air pollutant groups. They are harmful for human health as well as our environment and exposure to them is inevitable. Due to these reasons, VOC removal is the need of time. This article studied the photocatalytic oxidation performance of superhydrophobic-visible light-activated PFOTES-CV-based TiO 2 paints against VOCs. These photocatalytic TiO 2 paints are reported to have bactericidal activity under visible light in the literature. We have investigated their photocatalytic performance against toluene, p-xylene, and acetaldehyde under visible light. Various parameters such as the input concentration of toluene, amount of PFOTES, light power, and humidity were also examined. These paints successfully decomposed VOCs such as toluene, p-xylene, and acetaldehyde. These paints have high potential for commercialization.
... VOCs cause hazard risks to human health; assuming how they come into contact with the human body will have different influences on human health (8). Central nervous system reactions such as dizziness, headache, short-term memory loss, eye, nose, and throat irritation, the effects on the respiratory system, the genetic mutations, and the consequent birth of premature infants are the VOC effects reported in various research (9)(10)(11). VOCs include a large group of hydrocarbons, which can evaporate at ambient temperature and atmospheric pressure due to their high vapor pressure (12). ...
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Oil industries, such as oil refineries, are important sources of volatile organic compound production. These compounds have significant health effects on human health. In this study, a health risk assessment is carried out on volatile organic compounds (VOCs) in the recovery oil plant (ROP) unit of a refinery in southwest Iran. It was performed using the SQRA ¹ method including respiratory risk for chronic daily intake (CDI) of VOCs and cancer risk and non-cancer risk indices. Five locations in the area of oil effluents and five locations in the refinery area (control samples) were considered for evaluation. The sampling was done according to the standard NIOSH-1501 and SKC pumps. The gas chromatography/flame ionization detector (GC/FID) method was used to extract VOCs. The cancer slope factor (CSF) and respiratory reference dose (RFC) were calculated in addition to the respiratory risk (CDI). The end result shows that a significant difference was observed between the concentrations of volatile organic compounds in the two groups of air ( P < 0.05). The SQRA risk assessment showed that the risk levels of benzene for workers in the pit area were very high (4–5). Health hazard levels were also evaluated as high levels for toluene (2–4) and moderate levels for xylene and paraxylene (1–3). The cancer risk assessment of volatile organic compounds recorded the highest level of cancer risk for benzene in the range of petroleum effluents (>1). Also, a non-cancer risk (HQ) assessment revealed that benzene had a significant health risk in the range of oil pits (2–3). Based on the results, petroleum industries, including refineries, should conduct health risk assessment studies of volatile organic compounds. The units that are directly related to the high level of VOCs should be considered sensitive groups, and their employees should be under special management to reduce the level of exposure to these compounds and other hazardous compounds.
... The presence of these compounds in fracturing operations and fluid-shale studies presents unique challenges associated with produced water treatment, water reuse, and environmental concerns relating to water resource contamination. Many VOCs and SVOCs have adverse health effects after long-term exposure, predominantly affecting respiratory function, impairing human development and endocrine cycles, and causing various cell mutations leading to cancer in humans [8,44]. The VOCs observed in the reactions (Fig. 1) are similar to those reported in produced fluids sampled during field operations [10]. ...
Article
Oil and gas production from organic-rich shale formations has become viable through advancements in multistage hydraulic fracturing. However, fluctuations in oil and gas prices, coupled with the sharp decline in gas production after the initial days of fracturing operations, drive operators to devise strategies for enhancing hydrocarbon production. The use of highly reactive fracturing fluids that include strong oxidizing agents, also known as breakers, can potentially increase well productivity. The oxidative breakers are used to reduce the viscosity of gel-based fluids after the proppant is transported into fracture zones of the target formation. These breakers can also degrade the organic matter, enhancing the release of hydrocarbons. However, chemical byproducts generated by the interaction of oxidative breakers with the shale matrix have not been extensively studied. This study investigated the fluid-rock interactions between Marcellus Shale and synthetic hydraulic fracturing fluid (HFF) solutions comprising three different oxidative breakers, i.e., ammonium persulfate, sodium bromate, and sodium hypochlorite, commonly used in the Appalachian Basin, USA. Our results demonstrate that the type of oxidizing breakers used in the HFF controlled the type and amount of volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs) produced. In all HFF reacted effluents, we observed the transformation of VOCs and the presence of organic acids in variable amounts. However, effluents from HFF containing sodium bromate and sodium hypochlorite breakers showed the presence of several halogenated organic compounds. Changes in major ions and mineralogy indicate that carbonate dissolution and barite precipitation were ubiquitous in all shale reacted effluents. Our results also demonstrate that the addition of oxidative breakers increased the concentration of several major and trace elements in the effluents. These elements fall under the critical mineral (CM) or critical element category due to their high demand in emerging technologies and susceptibility to supply chain disruption due to variety of factors. However, before oxidative breakers can be used at a larger field scale to enhance the release and recovery of CM and hydrocarbons, a better understanding is required of the potential environmental impacts associated with the generation and transformation of contaminants during breaker-fluid-rock interaction.
... Environmental legislation drives increasing emphasis on removing toxic organic pollutants, like volatile organic compounds (VOCs), from air. 1 Among VOCs, propene is one of the main components of tobacco smoke, and it is present in vehicle emissions and exhaust gases from several industries (petrochemicals, foundry processes, etc.). 2,3 It has important harmful effects on human health, even at low concentrations. ...
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A series of nanostructured boron-TiO2 photocatalysts (B-X-TiO2-T) were prepared by sol-gel synthesis using titanium tetraisopropoxide and boric acid. The effects of the synthesis variables, boric acid amount (X) and crystallization temperature (T), on structural and electronic properties and on the photocatalytic performance for propene oxidation, are studied. This reaction accounts for the remediation of pollution caused by volatile organic compounds, and it is carried out at low concentrations, a case in which efficient removal techniques are difficult and costly to implement. The presence of boric acid during the TiO2 synthesis hinders the development of rutile without affecting the textural properties. X-ray photoelectron spectroscopy analysis reveals the interstitial incorporation of boron into the surface lattice of the TiO2 nanostructure, while segregation of B2O3 occurs in samples with high boron loading, also confirmed by X-ray diffraction. The best-performing photocatalysts are those with the lowest boron loading. Their high activity, outperforming the equivalent sample without boron, can be attributed to a high anatase and surface hydroxyl group content and efficient photo-charge separation (photoelectrochemical characterization, PEC), which can explain the suppression of visible photoluminescence (PL). Crystallization at 450 °C renders the most active sample, likely due to the development of a pure anatase structure with a large surface boron enrichment. A shift in the wavelength-dependent activity profile (PEC data) and the lowest electron-hole recombination rate (PL data) are also observed for this sample.
... The parent study will evaluate a community health worker (CHW) intervention through a clusterrandomized trial aimed at reducing volatile organic compound (VOC) exposures in auto body shops and beauty salons in metropolitan Tucson, Arizona. VOCs can cause several negative health outcomes, such as respiratory irritation, neurological disease, reproductive disorders, or cancer (Indoor Air Pollution: An Introduction for Health Professionals, 1995;Soni et al., 2018;Fimbres et al., 2021). We had initiated business recruitment for this study when the pandemic began, which halted our research temporarily. ...
Article
The COVID-19 pandemic has simultaneously exacerbated and elucidated inequities in resource distribution for small businesses across the United States in terms of worker health and the financial stability of both owners and employees. This disparity was further intensified by the constantly changing and sometimes opposing health and safety guidelines and recommendations to businesses from the local, state, and federal government agencies. To better understand how the pandemic has impacted small businesses, a cross-sectional survey was administered to owners, managers, and workers (n = 45) in the beauty and auto shop sectors from Southern Arizona. The survey identified barriers to safe operation that these businesses faced during the pandemic, illuminated worker concerns about COVID-19, and elicited perceptions of how workplaces have changed since the novel coronavirus outbreak of 2019. A combination of open-ended and close-ended questions explored how businesses adapted to the moving target of pandemic safety recommendations, as well as how the pandemic affected businesses and workers more generally. Almost all the beauty salons surveyed had to close their doors (22/25), either temporarily or permanently, due to COVID-19, while most of the auto repair shops were able to stay open (13/20). Beauty salons were more likely to implement exposure controls meant to limit transmission with customers and coworkers, such as wearing face masks and disallowing walk-ins, and were also more likely to be affected by pandemic-related issues, such as reduced client load and sourcing difficulties. Auto shops, designated by the state of Arizona to be ‘essential’ businesses, were less likely to have experienced financial precarity due to the pandemic. Content analysis of open-ended questions using the social-ecological model documented current and future worker concerns, namely financial hardships from lockdowns and the long-term viability of their business, unwillingness of employees to return to work, uncertainty regarding the progression of the pandemic, conflict over suitable health and safety protocols, and personal or family health and well-being (including anxiety and/or stress). Findings from the survey indicate that small businesses did not have clear guidance from policymakers during the pandemic and that the enacted regulations and guidelines focused on either health and safety or finances, but rarely both. Businesses often improvised and made potentially life-changing decisions with little to no support. This analysis can be used to inform future pandemic preparedness plans for small businesses that are cost-efficient, effective at reducing environmental exposures, and ultimately more likely to be implemented by the workers.
... Indeed, www.neuroquantology.com Hamoud Alenezi et al / A Review of Hazard Management in Petroleum/Chemical facilities-Fires and Explosions exposure to volatile organic compounds (VOCs), which are emitted through the combustion of fuels (among other causes) (see Figure 12), has been linked to major health issues such as cancer [88], memory problems,irritation of the eyes and respiratory tract, and liver, renal, and central nervous system damage [89].Identifying the sources of VOCs is critical for controlling air quality and preventing pollution [90]. Another type of air pollution happens as a consequence of chemical reactions with some other pollutants, such as atmospheric gases; these are referred to as secondary pollutants such as ozone. ...
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The purpose of this article is to provide an overview of the hazards and risks associated with the Petroleum/Chemical sector to students, scholars, governments, and non-governmental organizations. The evaluation concentrated on fire and explosion as the most evident risks that frequently occur in these facilities. It is critical to any country's economic prosperity. A discussion of the different casual features of such threats at various Petroleum/Chemical sites is offered. The most typical cause factors are combustible materials, static electricity, and lightning strikes, among others. The impact of risk mitigation and management studies based on various approaches and techniques, such as qualitative, quantitative, and dynamic changes in risk assessment, is clearly highlighted. According to most research publications, tank farms are the most dangerous region in the plant for sparking fires.The secondary effects of fire and explosions, such as the domino effect and air pollution, are investigated. To summarize, all efforts must be coordinated in order to successfully manage risks and crises in Petroleum/Chemical facilities and prevent their recurrence in the future.
... Known sources of these compounds are tobacco smoke, traffic exposure, and paint solvents. In the presence of these compounds, skin and eye irritation, sensitivity, effects on the central nervous system, carcinogenicity, and effects on the liver and kidneys have been reported (Mögel et al. 2011;Soni et al. 2018). According to the results obtained in Fig. 1, it was identified that the average concentration of styrene was 24.11 μg/L (with a range of 0.5-46.4 ...
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The aim of this study was to evaluate the levels of inorganic and organic substances as well as microbial contaminants in bottled drinking water on a global scale. The findings were compared to WHO guidelines, EPA standards, European Union (EU) directive, and standards drafted by International Bottled Water Association (IBWA). Our review showed that 46% of studies focused on the organic contaminants, 25% on physicochemical parameters, 12% on trace elements, 7% on the microbial quality, and 10% on microplastics (MPs) and radionuclides elements. Overall, from the 54 studies focusing on organic contaminants (OCs) compounds, 11% of studies had higher OCs concentrations than the standard permissible limit. According to the obtained results from this review, several OCs, inorganic contaminants (IOCs), including CHCl3, CHBrCl2, DEHP, benzene, styrene, Ba, As, Hg, pb, Ag, F, NO3, and SO4 in bottled drinking water of some countries were higher than the international guidelines values that may cause risks for human health in a long period of time. Furthermore, some problematic contaminants with known or unknown health effects such as EDCs, DBP, AA, MPs, and some radionuclides (40K and 222Rn) lack maximum permissible values in bottled drinking water as stipulated by international guidelines. The risk index (HI) for OCs and IOCs (CHBrCl2, Ba, As, and Hg) was higher than 1 in adults and children, and the value of HI for CHCl3 in children was more than 1. Thus, further studies are required to have a better understanding of all contaminants levels in bottled drinking water.
... Volatile organic compounds (VOCs) are the most common forms of air pollutants generated from chemical, petrochemical, pharmaceutical, building materials and printing industries. VOCs can remain in the atmosphere for up to 60 days while affecting directly the human health since some of them are carcinogenic and can alter the body's functions [1][2][3][4][5]. These compounds highly affect the environment since they are the primary causes of photochemical reactions in the atmosphere causing the formation of tropospheric ozone [6,7]. ...
Article
The present work reports the impregnation of palladium (Pd) or platinum (Pt) on hierarchical porous zeolite catalysts for Volatile Organic Compounds (VOCs) oxidation. The hierarchical porous zeolite (NaYmod) was synthesized via a top-down approach to incorporate mesoporosity into the microporous zeolite NaY. This process was achieved through a three steps synthesis: dealumination, desilication and alkaline treatment. 0.5 wt% of Pd and Pt precursors were then added to NaY and NaYmod supports by wet impregnation in order to elaborate efficient catalysts for the total oxidation of two types of VOCs, ethanol and toluene, which are probe molecules for oxygenated VOCs and BTEX compounds respectively. The supported and unsupported samples were characterized by X-Ray Diffraction (XRD), N2-physisorption, Transmission Electron Microscopy (TEM), and X-Ray Photoelectron Spectroscopy (XPS). The modified mesostructured support ensures a better dispersion of the active phases and led to a partial presence of highly reactive Pt(II) species in the case of platinum-based samples. Whatever the oxidation reaction, these latter demonstrate higher conversions compared to palladium-based ones. The presence of Pt(II) species provided a high catalytic performance, with a total degradation of both VOC probe molecules at temperatures lower than 170 °C. Such temperatures have not been recorded before for NaY supported materials.
... The presence of hazardous gaseous pollutants (e.g., volatile organic compounds (VOCs)) is generally related to their adverse impacts on human health (Soni et al., 2018;Rouf et al., 2022;Li and Yan, 2022). Among various VOCs, formaldehyde (FA) has been considered a key target due to its high carcinogenicity (Manjunath et al., 2021;Jalali et al., 2021). ...
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Under dark/low temperature (DLT) conditions, the oxidative removal of gaseous formaldehyde (FA) was studied using eggshell waste supported silver (Ag)-manganese dioxide (MnO2) bimetallic catalysts. To assess the synergistic effects between the two types of metals, 0.03%-Ag-(0.5-5%)-MnO2/Eggshell catalysts were prepared and employed for DLT-oxidation of FA. The steady-state FA oxidation reaction rate (mmol g⁻¹ h⁻¹), when measured using 100 ppm FA at 80°C (gas hourly space velocity (GHSV) of 5,308 h⁻¹), varied as follows: Ag-1.5%-MnO2/Eggshell-R (9.4) > Ag-3%-MnO2/Eggshell-R (8.1) > Ag-1.5%-MnO2/Eggshell (7.5) > Ag-5%-MnO2/Eggshell-R (7.2) > Ag-1.5%-MnO2/CaCO3-R (6.8) > MnO2-R (6) > Ag-0.5%-MnO2/Eggshell-R (3.2) > Ag/Eggshell-R (2.6). Here, ‘R’ denotes hydrogen-based thermochemical reduction pretreatment. The temperature required for 90% FA conversion (T90) at the same GHSV exhibited a contrary ordering: Ag/Eggshell-R (175°C) > Ag-0.5%-MnO2/Eggshell-R (123°C) > Ag-5%-MnO2/Eggshell-R (113°C) > MnO2-R (99°C) > Ag-1.5%-MnO2/Eggshell (96°C) > Ag-3%-MnO2/Eggshell-R (93°C) > Ag-1.5%-MnO2/Eggshell-R (77°C). The eggshell catalyst outperformed the commercial calcium carbonate variety due to the presence of defects in the former. The MnO2 co-catalyst enhances the capture and activation of atmospheric oxygen (O2) to boost the overall activity through rapid catalytic regeneration. Also, MnO2 favorably captures the hydrogen of the adsorbed FA molecules to make the oxidation pathway thermodynamically more favorable.
... 67 Even the total VOCs and individual VOC levels were much lower than the limits (except acrolein); the risk of VOC exposure needs attention due to the harmful effects of long-term VOC exposure. 91 It appeared that putting the mask in a well-ventilated place or heating up ($50 C) could help to remove VOC residues before wearing. 67 More research about the impact of long-term wearing of masks on wearers is encouraged. ...
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The coronavirus disease 2019 (COVID-19) has swept the world and still afflicts humans. As an effective means of protection, wearing masks has been widely adopted by the general public. The massive use of disposable masks has raised some emerging environmental and bio-safety concerns: improper handling of used masks may transfer the attached pathogens to environmental media; disposable masks mainly consist of polypropylene (PP) fibers which may aggravate the global plastic pollution; and the risks of long-term wearing of masks are elusive. To maximize the utilization and minimize the risks, efforts have been made to improve the performance of masks (e.g., antivirus properties and filtration efficiency), extend their functions (e.g., respiration monitoring and acting as a sampling device), develop new disinfection methods, and recycle masks. Despite that, from the perspective of the life cycle (from production, usage, and discard to disposal), comprehensive solutions are urgently needed to solve the environmental dilemma of disposable masks in both technologies (e.g., efficient use of raw materials, prolonging the service life, and enabling biodegradation) and policies (e.g., stricter industry criteria and garbage sorting).
... In the meantime, such activities are generally accompanied by the emission of airborne pollutants such as volatile organic compounds (VOC). Indeed, VOC are key pollutants that are ubiquitous in indoor air [1][2][3]. As such, it is imperative to implement proper management measures to control VOC levels in indoor air. ...
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Article
The development of practical photocatalytic system is of great significance in pursuit of efficient removal of hazardous volatile organic compounds (VOC) in indoor environments. The photocatalytic degradation (PCD) of VOC, if assessed in terms of conversion efficiency (e.g., into intermediate/by-product species), is affected by the combined effects of multiple variables in the reaction environment such as relative humidity (RH) level and oxygen (O2) content. In this research, the interactive relationship between such variables (e.g., RH from 0 to 100% and the O2 level from 0 to 21%) has been studied in a dynamic flow reactor in relation to the overall PCD efficiency using the titanium dioxide-supported platinum (Pt/TiO2) and m-xylene (X) as models for photocatalyst and target aromatic VOC, respectively. Accordingly, the presence of water (H2O) molecules and O2 can significantly increase the PCD efficiency to mineralize xylene based on the H2O-O2 synergy through the generation of a large number of reactive oxygen species (ROS: e.g., superoxide anion and hydroxyl radicals from the adsorbed O2 and H2O molecules, respectively) under ultraviolet (UV) irradiation. The detailed information acquired in this research is expected to offer valuable insights into the degradation pathways of aromatic VOC and the interactive roles between PCD process variables.
... Today, numerous pollutants like ozone, nitrogen oxides, or Volatile Organic Compounds are encountered in the atmosphere and are responsible for various severe health issues. They can cause different respiratory diseases like asthma but also skin irritations, immune responses, and cancer [1][2][3][4][5]. Some of these pollutants are also the most important greenhouses gases [6]. ...
Article
Volatile Organic Compounds (VOCs) are harmful for both human beings and environment and, consequently their removal from atmosphere by adsorption is one of the most scrutinized techniques owing to its easy implementation as well as its promising results for a wide range of molecules. Kaolinite, one of the most abundant and cheap clay, appears as a good candidate and has already been studied for the removal of various other pollutants such as pharmaceuticals. Here we used first–principles modelling techniques – static Density Functional Theory and Ab Initio Molecular Dynamics to investigate the interaction of kaolinite surfaces with phenol and toluene, two highly dangerous VOCs, as well as of carbon dioxide and water, two abundant atmospheric molecules. We showed that dispersion interactions play an important role in the adsorption mechanisms, especially for the adsorption on the siloxane surface. All the considered molecules preferentially adsorb on the aluminol-terminated surface. Also, we demonstrate that phenol is the most adsorbed molecule on both basal surfaces of kaolinite. On aluminol surface, phenol (-87.1 kJ.mol⁻¹) and toluene (-68.2 kJ.mol⁻¹) adsorb more strongly than water (-62.4 kJ.mol⁻¹) and CO2 (-35.0 kJ.mol⁻¹). Therefore, kaolinite could achieve a selective removal of phenol and toluene from air.
... Many VOCs are indeed classified as toxic and might cause asthma and other respiratory symptoms/diseases, headaches, nausea, or more severe problems such as convulsions and comas [91]. Some VOCs are also recognized as carcinogenic, especially targeting the liver, kidneys, brain, and nervous system [92]. Therefore, the analysis of VOCs in indoor environments is crucial to determine eventual chronic exposition to toxic chemicals and to avoid severe health issues. ...
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The efficient and selective detection of volatile organic compounds (VOCs) provides key information for various purposes ranging from the toxicological analysis of indoor/outdoor environments to the diagnosis of diseases or to the investigation of biological processes. In the last decade, different sensors and biosensors providing reliable, rapid, and economic responses in the detection of VOCs have been successfully conceived and applied in numerous practical cases; however, the global necessity of a sustainable development, has driven the design of devices for the detection of VOCs to greener methods. In this review, the most recent and innovative VOC sensors and biosensors with sustainable features are presented. The sensors are grouped into three of the main industrial sectors of daily life, including environmental analysis, highly important for toxicity issues, food packaging tools, especially aimed at avoiding the spoilage of meat and fish, and the diagnosis of diseases, crucial for the early detection of relevant pathological conditions such as cancer and diabetes. The research outcomes presented in the review underly the necessity of preparing sensors with higher efficiency, lower detection limits, improved selectivity, and enhanced sustainable characteristics to fully address the sustainable manufacturing of VOC sensors and biosensors.
... In 2019, PM 2.5 pollution was estimated as the third largest contributor to China's premature mortality, with ozone pollution estimated as the 21st contributor. 1 Precursors to ozone and PM 2.5 formation include volatile organic compounds (VOCs), also possessing their own toxicity and emitted from a variety of sources including vehicle emissions, solvent use, and hazardous wastes. 2 To alleviate the adverse impacts of PM 2.5 , ozone, and VOCs, controls on VOC emissions are crucial for public health protection. ...
... Air pollution control is essential for environmental protection. Volatile organic compounds (VOCs) are both indoor and outdoor pollutants with complicated and lasting life-threatening health impacts, which grasp attention of researchers (Soni et al. 2018). VOCs are a large group of compounds with distinct properties; these have been described as aromatic and aliphatic (Shaw et al. 2020), as well as oxygenated (Le Bras et al. 2002) and possessing halohydrocarbons . ...
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Emission control of volatile organic compounds (VOCs) from industrial sources is a frontline defense against air pollution in China. Owing to the complexity of chemical processing technologies and reaction mechanisms of VOCs, it is extremely difficult to pinpoint specific emission sources in a large-scale industrial region due to the synergy of various chemical processes. In this research, a comprehensive on-site emission profile of a representative petrochemical industrial park in East China is set up with measurements conducted using photochemical assessment monitoring stations (PAMSs) and the TO-15 method as per the United States Environmental Protection Agency. This is followed by a quantitative ozone formation potential (OFP) analysis, toxification analysis, and an on-site health risk assessment, covering each of 18 major facilities’ three sections: the refinery, chemical manufacturing zone, and wastewater treatment zone. The number of facilities and detected species studied in this research exceeds that of a former similar study. This study shows that the majority of VOC emissions from those enterprises possessing the largest impact on the environment are hydrocarbons: alkanes, olefin (alkenes, alkynes), and aromatics (91% in total). Aromatics and olefins show the maximum contribution to OFP, which is consistent with the results of similar studies. VOCs, such as 1,3-butadiene, from refineries are key factors leading to long-term health impacts, with aromatics being a leading carcinogenic and noncarcinogenic factor.
... Among pollutants present in ambient air, volatile organic compounds (VOCs) are a primary class with well-known harmful properties (Soni et al., 2018;He et al., 2019;Xuan et al., 2020). VOCs can be divided into two major classes of polar (e.g., aldehydes, ketones, alcohols, and esters) and non-polar (e.g., aromatic hydrocarbons) based on configuration and physicochemical properties (Ryerson et al., 2001). ...
Article
For efficient treatment of volatile organic compounds (VOCs), the potential of titanium dioxide (TiO2)-supported platinum (Pt) catalyst (Pt/TiO2) was investigated for low-temperature catalytic oxidation against three targets (i.e., formaldehyde (FA), acetaldehyde (AA), and toluene (T) (10–100 ppm range)) both individually and as a mixture. Accordingly, 100% mineralization of FA (50–200 ppm), AA (10 ppm), and T (10 ppm) was achieved by 1%-Pt/TiO2-R (‘R’ suffix for reduction pretreatment on the catalyst) at 30, 190, and 160 °C, respectively. The carbon dioxide (CO2) yield was used to assess the extent of VOC mineralization using air as the carrier gas (at 0.2 L atm min ̶ 1 flow rate). Their conversion efficiency was lowered with increases in the pollutant concentration or decreases in the bed mass. Furthermore, the reaction intermediates and catalytic pathways were assessed based on in-situ diffuse reflectance infrared Fourier transform spectroscopy. This study offers valuable insights into the interactive roles between process variables and into their effects on the overall performance of low-temperature thermocatalytic oxidation against single and/or multi-component gaseous VOC systems.
... Waste gases can contain a variety of volatile hydrocarbons, alkanes, alcohols, ketones, aldehydes, aromatics, organic acids, ethers, aldehydes, and others. Their emissions into the environment originate mainly from the petroleum and chemical industry, the production of solvents, cleaning products, printing machines, and others [1][2][3]. In particular, benzene is one of the most dangerous and carcinogenic representatives of VOCs due to its aromatic nature and high structural stability, requiring extreme experimental conditions for its removal [4,5]. ...
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Article
In order to obtain highly active catalytic materials for oxidation of carbon monoxide and volatile organic compounds (VOCs), monometallic platinum, copper, and palladium catalysts were prepared by using of two types of ZSM-5 zeolite as supports—parent ZSM-5 and the same one treated by HF and NH4F buffer solution. The catalyst samples, obtained by loading of platinum, palladium, and copper on ZSM-5 zeolite treated using HF and NH4F buffer solution, were more active in the reaction of CO and benzene oxidation compared with catalyst samples containing untreated zeolite. The presence of secondary mesoporosity played a positive role in increasing the catalytic activity due to improved reactant diffusion. The only exception was the copper catalysts in the reaction of CO oxidation, in which case the catalyst, based on untreated ZSM-5 zeolite, was more active. In this specific case, the key role is played by the oxidative state of copper species loaded on the ZSM-5 zeolites.
... Volatile organic compounds (VOCs) are toxic molecules emitted into the atmosphere from various sources (Montero-Montoya et al., 2018), such as fuel and carbon combustion processes. VOCs are also released during the manufacturing processes and applications of adhesives, solvents, paints, and plastics (Soni et al., 2018;Friedrich and Obermeier, 1999). Owing to the increase in the use of VOC-containing products in daily life and efficient insulation and less external ventilation of buildings, VOC exposure has significantly increased, making them the most common indoor air pollutants (Tsai, 2019), (Tsai, 2016). ...
Article
Here, we report the fabrication of nanofibrous air-filtration membranes of intrinsically microporous polyimide with metal–organic frameworks (MOFs). The membranes successfully captured VOCs from air. Two polyimides with surface areas up to 500 m² g⁻¹ were synthesized, and the impact of the porosity on the sorption kinetics and capacity of the nanofibers was investigated. Two Zr-based MOFs, namely pristine UiO-66 (1071 m² g⁻¹) and defective UiO-66 (1582 m² g⁻¹), were embedded into the nanofibers to produce nanocomposite materials. The nanofibers could remove polar formaldehyde and non-polar toluene, xylene, and mesitylene from air. The highest sorption capacity with 214 mg g⁻¹ was observed for xylene, followed by mesitylene (201 mg g⁻¹), toluene (142 mg g⁻¹), and formaldehyde (124 mg g⁻¹). The incorporation of MOFs drastically improved the sorption performance of the fibers produced from low-surface-area polyimide. Time-dependent sorption tests revealed the rapid sequestration of air pollutants owing to the intrinsic porosity of the polyimides and the MOF fillers. The porosity allowed the rapid diffusion of pollutants into the inner fiber matrix. The molecular level interactions between VOCs and polymer/MOFs were clarified by molecular modeling studies. The practicality of material fabrication and the applicability of the material were assessed through the modification of industrial N95 dust masks. To the best of our knowledge, this is the first successful demonstration of the synergistic combination of intrinsically microporous polyimides and MOFs in the form of electrospun nanofibrous membranes and their application for VOC removal.
... Widespread emission of volatile organic compounds (VOCs) to the atmosphere is considered a major global environmental hazard due to the toxic, mutagenic, and carcinogenic nature of the organic pollutants and their involvement in the formation of the photochemical smog [134]. The main sources of VOCs pollution are industrial processes and transportation activities. ...
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The use of titania-based composite materials in the field of heterogeneous catalysis and photocatalysis has a long and rich history. Hybrid structures combining titania nanoparticles with clay minerals have been extensively investigated for nearly four decades. The attractiveness of clay minerals as components of functional materials stems primarily from their compositional versatility and the possibility of using silicate lamellae as prefabricated building blocks ready to be fitted into the desired nanoconstruction. This review focuses on the evolution over the years of synthetic strategies employed for the manufacturing of titania–clay mineral composites with particular attention to the role of the adopted preparative approach in shaping the physical and chemical characteristics of the materials and enabling, ultimately, tuning of their catalytic and/or photocatalytic performance.
... Some volatile organic compounds (VOCs) are toxic, carcinogenic, and mutagenic pollutants. Emissions of harmful VOCs are directly concerned with many industrial processes, transportation, etc. [21][22][23]. The presence of high concentration of lower hydrocarbons, leakage of hydrogen fuels, and its explosion into the air are significant concerns for the environment [24]. ...
Article
The presence of toxic and harmful gases utterly dangers human health and environmental well-being. Selective detection of these gases is immediately required to meet the demands of society. A promising and presently thriving area for monitoring volatile organic compounds (VOCs) and combustible gases stems from the evolution of detection strategies meld with metal-oxide-based nano-materials. Even though the prevailing literature in nanoscience covers numerous reports on chemical sensing merged with nanotechnology, a few have focused on gas detection. This review takes the lead to study, categorize, and inspect the progressive gas detection approaches accessible in literature. Each gas sensing technique is analyzed based on the detection principle and is reviewed on various aspects such as gas detection, sensitivity, response /recovery time, sensor parameters, procedural complexity, detection variables, and sensor characteristics. Furthermore, this investigation serves as a valuable reference for researchers to recognize the mechanism behind the gas sensor’s fundamental facets. Concisely, this review elucidates the state of this field and induces/propels further research in this field.
... High concentrations of CAC can lead to breathing problems especially on those who are already affected by respiratory diseases and illnesses such as asthma; moreover, CACS are also harmful by undermining the immune system, weakening the human body's natural ability to defend itself against bacteria and viruses [32]. Studies in literature show the correlation between CAC emissions and diseases [33] such as bronchitis and asthma [34] and even with premature deaths, with over 400,000 premature deaths associated with PM2.5 and NOx across the 28 EU countries in 2016 [35]. The latest MARPOL indications set the SOx and PMs acceptable limits to 0.1% for ECAs, and from 3.5% to 0.5% for areas outside ECAs. ...
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Article
In recent decades, maritime transport demand has increased along with world population and global trades. This is associated with higher pollution levels, including the emissions of GHG and other polluting gases. Ports are important elements within maritime transport and contribute themselves to pollutant emissions. This paper aims to offer a comprehensive yet technical review of the latest related technologies, explaining and covering aspects that link ports with emissions, i.e., analyzing, monitoring, assessing, and mitigating emissions in ports. This has been achieved through a robust scientific analysis of very recent and significant research studies, to offer an up-to-date and reliable overview. Results show the correlation between emissions and port infrastructures, and demonstrate how proper interventions can help with reducing pollutant emissions and financial costs as well, in ports and for maritime transportation in general. Besides, this review also wishes to propose new ideas for future research: new future experimental studies might spin-off from it, and perhaps port Authorities might be inspired to experiment and implement dedicated technologies to improve their impact on environment and sustainability.
... In the lone example directly supporting their superior phytoscreening capabilities, galls induced on blueberry bushes sampled from a field adjacent to a point source of contamination (an ore smelter) accumulated two HMs (copper and nickel) in higher concentrations than fruit, leaves, twigs and roots (Bagatto and Shorthouse 1991). Third, to the best of our knowledge, there is no single study published that explores the use of insect-induced plant galls as phytoscreeners of organic contaminants such as industrial VOCs-a group of compounds ubiquitously found in the environments due to, for example, their use in solvents, petroleum fuels, hydraulic fluids, paint thinners, and chlorinated water treatments-that can negatively influence human health (Rowe et al. 2007;Huang et al. 2014;Soni et al. 2017). Taken collectively, these studies highlight the need to incorporate tests of the accumulation of multiple contaminant types in a more robust, comparative framework across plant tissue types to better understand the phytoscreening capabilities of insect-induced plant galls. ...
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Article
Purpose Detecting belowground chemical contamination is a challenging environmental problem due to subsurface heterogeneity and limited monitoring capabilities associated with labor-intensive, intrusive, and costly sampling techniques. With their extensive root systems, vascular plants are an easily accessible aboveground link to the subsurface. Therefore, plant tissues, particularly tree cores, are used in phytoscreening applications for detecting belowground chemical contaminants. While phytoscreening has been evolving as an alternative to traditional sampling, this method has caveats: (a) easier to harvest tissues such as leaves and twigs tend to exhibit lower concentrations than tree cores; (b) coring can negatively influence tree health; and (c) trees may be unavailable for sampling at all sites. Therefore, less invasive techniques that incorporate plants other than trees could be more effective phytoscreeners. Methods Here, we explore the use of insect-induced plant galls–that can be found on many vascular plant species–for their phytoscreening capabilities. Driven by observations that they can act as sinks for extraordinary high concentrations of nutrients during development, we tested the following hypothesis: galls will accumulate belowground chemical contaminants in higher concentrations compared to other aboveground plant tissues. Specifically, we measured and compared the concentrations of two contaminant types, inorganic heavy metals (HMs) and a volatile organic compound (VOC) and known human carcinogen, 1,4-dioxane, in four aboveground plant tissue types (leaf, twig, core, fruit) and insect-induced plant gall, across three plant types (shrub, tree, vine) sampled from contaminated areas. Results Twelve different HMs were present in shrubs, and 1,4–dioxane was present in both trees and vines; however, the concentrations of each contaminants varied quantitatively across plant tissue types. While galls accumulated the lowest concentrations of HMs, they accumulated the highest concentration of 1,4-dioxane, at five-times that of tree cores. Conclusion Given they can be found on many vascular plant species and are easy to collect when they are locally abundant, with further development, galls may be a powerful alternative for detecting belowground chemical contamination, particularly for VOCs in urban areas. We discuss the dichotomy in the ability of galls to detect inorganic HMs versus VOCs, and outline future questions that should be considered to further develop galls for phytoscreening application.
... In recent years, a number of papers were published investigating the relation of BVOCs and positive impact of forests on human health [42,[52][53][54]. Furthermore, it was reported that certain VOCs can have long-and short-term negative effects on human health and the majority of them have anthropogenic origin (AVOCs) [55]. On the other hand, it is known that during the photochemical reactions with AVOCs, VOCs of organic origin (BVOCs), including terpenes, can contribute to the creation of new air compounds, of which some can harm human health [56]. ...
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Article
Multiple positive effects that forests have on human health and overall well-being have been reported widely in the literature. Still, multiple elements of this relationship remain unidentified and unexplained. In this study, the composition of leaf volatile organic compounds (BVOCs) content in three common coniferous species: the Austrian pine (Pinus nigra), Scots pine (Pinus sylvestris) and Spruce (Picea abies), was analyzed. The specificity of BVOCs content in the examined species and their genotypes is observed as a plant potential to evaporate these organic compounds and potentially improve human health and well-being. Principal component analysis applied on BVOCs content among species showed significant differences between compounds that have previously been characterized as having positive effects on human health by acting as anticancer, anti-inflammatory, antiviral and antibacterial. Variations among genotypes of the investigated species were observed in the content of BVOCs relevant for human health improvement, such as limonene, terpinolene, β-pinene, linalool, camphene, camphor, citronellol and α-cadinol. The observed intra- and inter-species variations in the BVOCs content provide an appropriate base for further research on the forest–human health relationship, breeding and selection of the most suitable genotypes for human health improvement, and could I mpact the sustainable management of forests.
... The long-time exposure to contaminated air containing VOCs at even parts per billion (ppb v ) concentration levels, can lead to short-term and long-term diseases. Common health problems include nose, throat, eyes, and skin irritation, along with headaches, dizziness, and life-threatening diseases such as cancer (Soni et al., 2018). ...
Article
The use of biological reactors to remove volatile organic compounds (VOCs) from waste gas streams has proven to be a cost-effective and sustainable technique. However, hydrophobic VOCs exhibit low removal, mainly due to their limited bioavailability for the microorganisms. Different strategies to enhance their removal in bio(trickling)filters have been developed with promising results. In this review, two strategies, i.e. the use of surfactants and hydrophilic compounds, for enhancing the removal of hydrophobic VOCs in bio(trickling)filters are discussed. The complexity of the processes and mechanisms behind both strategies are addressed to fully understand and exploit their potential and rapid implementation at full-scale. Mass transfer and biological aspects are discussed for each strategy, and an in-depth comparison between studies carried out over the last two decades has been performed. This review identifies additional strategies to further improve the application of (bio)surfactants and/or hydrophilic VOCs, and it provides recommendations for future studies in this field.
... For example, the emission of VOCs in the atmosphere causes environmental problems such as greenhouse effect, photochemical smog, and ozone depletion. For human health, VOCs are absorbed by the respiratory system, causing brain and liver damages [237][238][239]. It is necessary to reduce the emission of VOCs into the atmosphere. ...
Thesis
The removal of pollutants from a gas mixture is a major issue in terms of minimizing the environment impact of numerous industrial processes. Ionic liquids are promising alternative solvents for traditional organic compounds using in selective separation due to their negligible vapor pressure and designable chemic-physical properties. In this study, a new concept, combination of ILs and a tubular ceramic membrane (ILM), has been developed with the aim of gas or liquid separation from feed streams. Comparing to conventional gas or liquid removal processes, ILMs provide high stability and mechanical resistance during long-time operation. Moreover, specific properties of ILs ensure selectivity and absorption capacity of ILMs. In the case of gas treatments, removal of humidity to protect gas sensor and treatment of industrial gas containing toluene are the two parts developed in this manuscript. Effects of several operating parameters, including gas flow rate, temperature, pressure, feed concentration, effective surface area of membrane (length of the support membrane) and position of gas channels, were investigated both on humidity and toluene (vapor) removal. In addition, a two-step model was used to simulate experimental results and evaluate the separation performance of ILMs. According to both experimental and simulated results, ILMs exhibited relative high absorption capacity of humidity and toluene. This new ILM process will be the dominating green processes for gas or liquid pollutants separation.
... Environmental pollution is still a paramount problem facing on a global scale, and its monitoring is becoming a foremost area of research for the protection of human health and our ecosystem [1][2][3]. There is plethora of potentially hazardous gas species and volatile organic compounds (VOCs) in our surroundings originated from a variety of sources such as vehicles, industries, and transportations [1,4]. Precise information about such harmful pollutants is essential to ensure the safety of human health and other living things. ...
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Chapter
For many years, gas sensors using semiconducting metal oxides and 2-D materials have provided a platform for environmental monitoring for more than two decades. However, these sensors require high operating temperature and external power supply or batteries, which is a great hindrance to their application in modern wearable/smart devices and the Internet of Things (IoT). Self-powered systems based on piezoelectric and triboelectric nanogenerators have the potential to overcome aforesaid limitations to some extent. These nanogenerators can scavenge environment mechanical energy into electrical output, which could be a promising alternative to external power source required for sensing devices, and can also be used as a source of energy for our rapidly increasing daily requirements. In this regard the new research has been proposed using the triboelectric or piezoelectric concept by coupling with gas sensing ability of semiconducting materials to avoid the inevitability of external power sources. A brief overview of the history and fundamentals about nanogenerators and potential applications of the self-supporting gas sensing system based on nanogenerators are provided in this chapter. This chapter could serve as a road map for leading researchers in the field of self-powered sensors of the next generation and highlight current developments in the area.
... The presence of a small amount of these VOCs in the air can cause unpleasant odors and toxicity. Also, the long-term exposure to these pollutants, even at levels of few parts per million, can cause life-threatening respiratory diseases like asthma, eye and throat irritations, and even cancer (Soni et al., 2018). ...
Article
Organic pollutants, with their increasing concentrations in the ambient air, are posing a severe threat to human health. Metal-organic frameworks (MOFs), due to their active functionalities and porous nature, have emerged as potential materials for the capture of organic pollutants and cleaning of the environment/air. In this work, the functionalization of cotton fabric is reported by the in-situ growth of zeolitic imidazolate framework (ZIF-8 and ZIF-67) MOFs on carboxymethylated cotton (CM Cotton) by employing a rapid and eco-friendly approach. The physicochemical characterization of the MOF functionalized fabrics ([email protected] Cotton and [email protected] Cotton) revealed uniform and wash durable attachment of porous ZIF nanocrystals on the surface of the fabric. These ZIF functionalized fabrics possessed high surface area and have been observed to adsorb significantly high concentrations of organic pollutants such as aniline, benzene, and styrene from ambient air. Interestingly these fabrics could be regenerated and reused repeatedly without any deterioration in their adsorption capacity. The negative and low binding energies calculated by DFT confirmed the physisorption of the aromatic pollutants on the surface of MOF functionalized fabrics. Such fabrics have a huge potential as protective textiles, anti-odor clothing, air purification filters, and related products.
Article
Benzene, toluene, ethylbenzene, and xylenes are commonly known as (BTEX) and include volatile organic compounds (VOCs) in ambient air. Exposure to some BTEX has been associated with health risks. This study aimed to reduce BTEX on the environment and human health dramatically. This research targeted decreasing the BTEX in an air environment by producing high surface area activated carbon (KA-AC) under optimized synthesis conditions from Ricinus communis as lignocellulosic waste using ZnCl2 solution, respectively. The influence of several activation parameters was investigated on the surface area, such as impregnation ratio, carbonization time, and carbonization temperature. The KA5-AC prepared under optimized conditions showed BET surface area and total pore volume of 1225 m2/g, and 0.72 cm3/g, respectively. The optimized synthesis conditions were as follows: 0.1, 0.5, 1, 2, and 5 M impregnation ratio, 450–950 °C carbonization temperature, and 100 min carbonization time. The characteristics of the optimized KA-AC were analyzed using nitrogen adsorption–desorption isotherm, scanning electron microscopy, and pore structural analysis. The results confirmed that the VOCs adsorption on KA-AC followed a monolayer adsorption isotherm over a homogeneous adsorbent surface. It showed the removal efficiency of benzene, toluene, ethylbenzene, and m, p-xylene (R2 = from 0.991 to 0.997). Moreover, the KA-AC exhibited good performance without considerable loss of efficacy throughout the experiments. Accordingly, it is concluded that developing low-cost activated carbon to use BTEX vapor adsorption research could be practical and developments to overcome for utilization in air pollution control.
Article
Persistence in the atmosphere of carbon dioxide (CO2) and volatile organic compounds (VOCs) represents a threat for human safety and health, both in the short and in the long term. Therefore, the removal, storage or, even better, utilization of these molecules is currently highly desirable. Photo-catalytic approaches aims to use the sunlight to afford this removal providing a limited or no further pollution. Wide band gap semiconductors are amongst the most studied and employed materials for this purpose. In this study, a crystalline (quartz) and an amorphous (SBA-15) type of silica were tested as TiO2 scaffolds in the photo-oxidation of VOCs. The photo-reduction of CO2 in presence of H2O was also considered as comparative reaction. Therefore, optical, chemical, and reflective properties of the synthesized materials were investigated. The two types of silica showed a different affinity and selectivity in both photo-reductive and photo-oxidative events. The light scattering properties of the scaffold were found to be effective as booster of the photo-catalytic performance of the active phase.
Article
Catalytic oxidation is a feasible method for remediating volatile organic compounds (VOCs), due to its lower energy consumption and mineralization of VOCs into H2O and CO2. Noble metal-based catalysts are preferred for the catalytic oxidation of VOCs because of their superior activity, but they are usually deactivated by thermal aging which sinters the metal particles. Here, we report that Pt-Pd/Al2O3 thermally aged at 700–900 °C in air showed enhanced catalytic activity for toluene oxidation in humid conditions. There were electronic and structural changes in the thermally aged Pt-Pd/Al2O3, as confirmed by numerous analyses. Both Pt and Pd existed in a metallic rather than oxidized state without additional reduction steps. The noble metal particles were assembled to form Pt-Pd alloy, in the form of isolated Pd atoms surrounded by Pt atoms. This specific alloy structure was found to be crucial to the observed enhancement in catalytic toluene oxidation at low temperature.
Article
Accurate prediction of temperature-dependent reaction rate constants of organic compounds is of great importance to both atmospheric chemistry and combustion science. Extensive work has been done on developing automated mechanism generation systems but the lack of quality reaction rate data remains a huge bottleneck in the application of highly detailed mechanisms. Machine learning prediction models have been recently adopted to alleviate the data gap in thermochemistry and have great potential to do the same for kinetic data with the recent release of quality reaction rate data compilations. The ultimate goal is to formulate easily accessible, general-purpose, temperature-dependent, and multitarget models for the prediction of reaction rates. To that end, we propose a model that depends on the well-known Morgan fingerprints as well as learned representations transferred from the QM9 data set. We propose the use of an Arrhenius-based loss where predictions of the three modified-Arrhenius parameters (A, n, and B = Ea/R) are given instead of the direct prediction of reaction rate constants. Our model is >35% more accurate compared to a baseline model of feed forward network (FFN) on Morgan fingerprints.
Chapter
Instead of indoor air pollution, outdoor air pollution usually gets more attention even though the level of indoor air pollution is much higher than outside air pollution and most individuals spend 70 to 80% of their lives in buildings with tight air control. Due to poor air quality, more than 6 million people die every year, which leads to significant financial loss due to a decrease in the productivity of employees, increased expenses of the healthcare system, and material damage. In indoor pollution many factors are involved, such as biological pollutants, particulate matter, and over almost 400 various inorganic and organic compounds, whose values are linked with various indoor and outdoor factors. It is not always feasible technically to prevent different pollutants, so there is a great requirement for implementing active and cost-effective reductions. Chemical and physical technologies haven't yet found a way to get rid of every pollutant in the home at the same time. This issue involves the employment of sequence-based technologies that require higher capital and operational expenditures. Indoor environments still restrict the efficacy of classic physical-chemical technologies due to a lack of concentrations, variation, and predictability. A catalyst is used in conjunction with several hybrid processes, including photolysis, plasma, and absorption, to reduce the amount of volatile organic compounds (VOCs) in the air. The mechanism of VOCs oxidation by various catalysts is elucidated by using different principles, e.g., Langmuir–Hinshelwood and Eley–Rideal mechanisms. Biotechnologies have evolved here as cost-effective, sustainable platforms that are able to meet these constraints based on plants, bacteria, fungus, and microalgae's biocatalytic activity. Biological filtration systems may enhance buildings’ energy efficiency while offering extra aesthetic and psychological advantages. In this chapter, in addition to recent progress in physical-chemical and biological technology for indoor pollutant reduction, a comprehensive assessment of indoor air pollution issues and methods for prevention are presented.
Article
Efficient removal of pollutants in the atmosphere is of great significance to human health and environmental restoration. Herein, we report the preparation of a self-supporting conjugated microporous polymers (CMPs) membrane (SS-CMPs-M) synthesized by Sonogashira-Hagihara (S–H) cross-coupling reaction using KBr tables as a template. The intrinsic hydrophobic chemical composition made it good hydrophobicity and lipophilicity, e.g., the water contact angles (WCA) for SS-CMPs-M were measured to be 113°. The aromatic building blocks of CMPs make SS-CMPs-M exceptionally stable physicochemical properties, i.e., the membrane exists stably below 300 °C, and they were insoluble in organic solvents. Additionally, the as-resulted SS-CMPs-M-1 which also presents mesoporous architecture shows effectively captures performance for particulate matter (PM) with different particle sizes in the air, the removal efficiency of PM2.5 and PM10 are 99.7% and 99.9%, respectively. For volatile organic compounds (VOCs) vapor in the air, the SS-CMPs-M-1 shows an excellent purification effect, the removal efficiency of formaldehyde in the simulated air is above 97%, and the AQI value of the filtered gas (>500) is reduced to 50. Taking advantage of its simple and scalable manufacture, the SS-CMPs-M-1 may have great potential as an advanced membrane for the separation and elimination of PM in different environments.
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Article
Giorgos Petrou and colleagues argue for systematic large scale monitoring of indoor air to avoid unintended harms to health from home energy efficiency programmes
Article
The role of gas sensors to detect and sense hazardous gases in the environment is very much important. Smart gas sensing is the need of the hour in the field of medical, environment, food spoilage monitoring, drug screening, civil security, and many more areas. Smart sensors can predict the presence of gas and its concentration. These Smart gas sensors require a precise flawless and miniaturized design of their integrated components. The perfect alignment of various integrated components decides its working capabilities such as power consumption, area of the device. Micro heaters play an important role in the design and fabrication of smart gas sensors. In this work, the design and optimization in the thickness parameter of meander shaped microheater are simulated on COMSOL Multiphysics software to achieve a uniform temperature distribution, elevated temperature, and low power consumption. The result obtained through simulation will help reduce the time and cost required for complex fabrication techniques such as Lithography, electrodeposition, and fabricating a microheater with uniform and higher temperature and low power consumption.
Article
Strontium‐doped lanthanum manganites, La1‐xSrxMnO3 (LSMO), are promising and affordable catalysts for oxidative degradation of volatile organic compounds (VOCs). LSMO catalysts (x = 0, 0.1, 0.2 and 0.3) were prepared by the citrate‐nitrate autocombustion (CNA) and coprecipitation synthesis. The phase composition was confirmed by X‐ray diffraction and Rietveld refinement analysis, while the oxygen content was determined by Mohr's salt permanganate titration. Morphology and porosity of prepared catalysts was correlated to catalytic oxidation of BTEX (benzene, toluene, ethylbenzene and o‐xylene). It was observed that both synthesis methods yielded catalysts of similar average pore size diameter and specific surface area, but the pore size distribution differed: CNA‐prepared catalysts had a multimodal pore size distribution, while the coprecipitated ones had a single maximum at 4 nm. Catalysts prepared by the CNA method have shown a higher catalytic activity in the temperature range 373 – 723 K, as the presence of Mn3+/Mn4+ mixed valences increased their reducibility. This article is protected by copyright. All rights reserved
Article
Gasoline evaporation from vehicle fuel tanks is a major source of VOCs, that represents a serious threat for both human health and environment. To limit these emissions, the most adopted strategy is to use a carbon canister filter to store fuel vapors and then burn them inside the engine along with the fresh charge. However, the canister saturation level is usually unknown, and it can easily reach the full saturation, especially in particular conditions. As hybrid vehicles are becoming more popular in the market, this issue becomes even more important, since canister purging phase has even less time to be performed. In this activity, a 1D transient, non-isothermal, non-adiabatic model has been developed to specifically simulate the carbon canister filter of a common EVAP system and analyze its behavior during fuel vapor adsorption, with particular attention to the mutual influence of carbons adsorption performance and temperature variation. The model presented is based on an adsorption isotherm derived from the potential theory of adsorption, and it has been developed to be usable with only few canister properties. A system of two coupled PDEs has been coded and solved in MATLAB® environment, and results have been compared to experimental data in terms of mass and internal temperature variation on a common European canister, found in a previous study, with a standard loading flow rate of n-butane mixture and standard environmental temperature. The model has then been analyzed by using the Design For Six Sigma (DFSS) method, which has allowed a good optimization on calibration parameters with a relatively low amount of tests. Results show a significant increment in the predictive capabilities of the optimized model (up to 90% of the experimental value), with respect to the first simulations. This model helps to understand and evaluate the influence of environmental temperature on the canister filter performance, and can be used for both canister design and control of the purging strategies performed by an on-road vehicle.
Article
The initial coal fly ash zeolites (CFAZ) were obtained from raw coal fly ash with two SiO2/Al2O3 ratios of 2.0 and 2.2 by hydrothermal activation or by two‐stage process with pre‐fusion at 550 oC or 800 oC. Microwave plasma surface treatment of CFAZ was performed to modify their surface properties and therefore their catalytic activity in total VOC oxidation. CHF3 and SF6 were used as plasma agents at two different times of treatments – 30 s and 60 s. The obtained hierarchal CFAZ were characterized by X‐ray diffraction (XRD), N2‐physisorption, Temperature programmed reduction (TPR) experiments, UV‐Vis spectroscopy and X‐ray photoelectron spectroscopy (XPS) to clarify the effect of plasma treatment on the surface and reduction properties, morphology and structure of the modified samples. The catalytic performance of the modified CFAZ was investigated in a flow system toward toluene oxidation in the temperature range of 250‐520 °C. It has been observed that CHF3 treatment favors the catalytic activity of CFAZ at shorter treatment duration, while SF6 plasma treatment inhibits their catalytic properties. The development of efficient low‐cost catalyst by utilization of coal fly ash will contribute on the one hand to the saving of critical raw materials such as platinum group metals (PGMs), and on the other to the utilization of the enormous resource of coal ash instead of its landfilling in accordance to the modern trends for development of circular economy and smart waste management. This article is protected by copyright. All rights reserved.
Chapter
This chapter aims to summarize the global air pollution problem critically through the comprehensive assessment of organic, inorganic, and biological sources; key challenges to identify the problem; and the remediation of these pollutants using nano- and/or bioremediation technologies. Air pollution has emerged as a global challenge due to its rising socioeconomic and health risks. The impacts and intensity of these pollutants have developed more critically, especially in developing countries that lack proper management and protection systems. Several clinical investigations have associated health disorders, poor quality of life, and rising mortality rates with pollutants present in the air we breathe. Among these air pollutants that cause serious health issues and increasing mortality rates, particulate matter of different sizes is alarming. The major air pollutants include SOx, NOx, O3, and particulate matter, which have been continuously increasing over the last two decades. Although substantial efforts have been made to describe the emerging issue of air pollution, the sources and nature of contributing factors and the identification and remediation methods remain inadequately understood. This study basically aims to use the available data and arrange them in a systematized way to help the scientific community to understand study gaps, critical challenges, and future possibilities toward sustainable environment. Moreover, the emerging bioremediation technologies based on nano- and biotechnological processes have been discussed in detail. A way forward while mentioning these technologies, the key issues and challenges that need further investigations have also been discussed.
Article
Colorimetric sensors have attracted increasing interest because their signals can be easily observed by the naked eye or using smartphones for in situ sensing applications. Sensor performance is directly determined by the reporter probes that produce colorimetric responses to targets. As newly emerging colorimetric materials for visual sensing applications, metal–organic frameworks (MOFs) with tunable colorimetric responses can be obtained through careful design. The properties of MOFs, such as a large surface area, porous structure, and crystalline nature, impart the corresponding colorimetric sensing platforms with excellent stability, sensitivity, selectivity, and ease of assembly. In this review, we focus on recent advances in the design and synthesis of MOFs with tunable colorimetric properties as well as reported MOF-based visual sensing applications for various analytes, including cations, anions, volatile organic compounds, gases, and water.
Article
Among the gas sensing technologies, microfluidic gas sensors have garnered attention because of their sensitivity, compact size, and low cost. In this study, we demonstrate improved selectivity of microfluidic gas sensors toward volatile organic compounds by increasing the effect of adsorption of analytes on the surface of the sensor’s microchannel through increasing the ratio of the surface area (in contact with analyte) to the volume of the microchannel. First, the effect of microchannel geometry modification (reduction of width) is studied through a computational parametric approach (which is validated experimentally). The results show an average improvement of 93.44% and 60.1% in selectivity toward polar and nonpolar VOCs, respectively. In the next step, the surface of the microchannel is modified with graphene quantum dots, which has a two-fold effect on VOCs adsorption: (i) increasing the surface area, and (ii) adding functional groups. The experimental results of this step show an average improvement of 101.45% and 98.82% in the sensor’s selectivity for the smallest widths toward polar and nonpolar VOCs, respectively. These results indicate that increasing the ratio of surface area (in contact with analyte) to the volume of the microchannel and adding functionalized nanofeatures to the microchannel surface area are promising ways to enhance the selectivity of microfluidic gas sensors.
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A new trend combining the concept of "green" buildings with the idea of preserving and strengthening peoples’ health in order to eliminate sick building syndrome and building related illnesses has been observed worldwide. The COVID – 19 pandemic consequences outlined the necessity of updating the regulatory framework considering health preserving built environment principles in order to create sustainable and comfortable living environments. Indoor air quality directly correlates with human health: exposure to polluted air increases the risk of cardiovascular disease, myocardial ischemia, angina pectoris, hypertension and heart disease. It is known that indoor air quality depends not only on ambient air quality, but also on indoor sources of chemical and biological pollutants. Existing regulatory framework does not cover the civil buildings indoor sources of air pollution topic. This article discusses the terms of the Russian national technical and hygienic standards concerning the indoor air quality. A comparative analysis of the Russian Federation regulatory framework that refers the civil buildings indoor air quality with international "green" standards was carried out. Based on the analysis, the necessity to update the Russian regulatory framework is highlighted.
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Our work sheds light on using the O 2p-band center as a useful electronic descriptor for understanding the variations in catalytic reducibility of transition metal oxides (TMOs) and the promotional effect of MnO2 during catalytic benzene combustion. The "volcano"-type activity plot, in conjunction with the reduction characteristic of the TMOs, ultimately reflects the Sabatier principle, which states that a good catalyst (i.e., MnO2) balances the capability of oxygen abstraction and uptake in the case of benzene combustion.
Chapter
The dimensional shrinkage of recent electronic components demands multifunctional sensor with less power-consuming devices. The flexible, stretchable, and skin-conformable sensor that can operate low-power personal electronics by harvesting mechanical and thermal energies from body movements and heat is of profound importance in the self-powered technology. The nanogenerator enables to change the mechanical and thermal energy into electricity by harvesting body movements and heat dissipation. The ongoing progress of energy harvesters is not only to harvest the mechanical and thermal energy but also to enhance electricity generation performance to implement in real-life problem. In this chapter, ongoing innovation on piezoelectric, pyroelectric, and their hybrid structure-based energy harvesters is discussed elaborately. In particular, device design engineering strategy and material geometrical feature onto the performance and mechanism of piezo- and pyroelectric energy harvesting are also highlighted. Based on the ongoing strategy, future prospects and still unexplored area of research and key challenges are concisely discussed.
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The world is presently infected by the biological fever of COVID-19 caused by SARS-CoV-2 virus. The present study is mainly related to the airborne transmission of novel coronavirus through airway. Similarly, our mother planet is suffering from drastic effects of air pollution. There are sufficient probabilities or evidences proven for contagious virus transmission through polluted airborne-pathway in formed aerosol molecules. The pathways and sources of spread are detailed along with the best possible green control technologies or ideas to hinder further transmission. The combined effects of such root causes and unwanted outcomes are similar in nature leading to acute cardiac arrest of our planet. To maintain environmental sustainability, the prior future of such emerging unknown biological hazardous air emissions is to be thoroughly researched. So it is high time to deal with the future of hazardous air pollution and work on its preventive measures. The lifetime of such an airborne virus continues for several hours, thus imposing severe threat even during post-lockdown phase. The world waits eagerly for the development of successful vaccination or medication but the possible outcome is quite uncertain in terms of equivalent economy distribution and biomedical availability. Thus, risk assessments are to be carried out even during the post-vaccination period with proper environmental surveillance and monitoring. The skilled techniques of disinfection, sanitization, and other viable wayouts are to be modified with time, place, and prevailing climatic conditions, handling the pandemic efficiently. A healthy atmosphere makes the earth a better place to dwell, ensuring its future lifecycle.
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Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants generated primarily during the incomplete combustion of organic materials (e.g. coal, oil, petrol, and wood). Emissions from anthropogenic activities predominate; nevertheless, some PAHs in the environment originate from natural sources such as open burning, natural losses or seeps of petroleum or coal deposits, and volcanic activities. Major anthropogenic sources of PAHs include residential heating, coal gasification and liquefying plants, carbon black, coal-tar pitch and asphalt production, coke and aluminum production, catalytic cracking towers and related activities in petroleum refineries as well as and motor vehicle exhaust. PAHs are found in the ambient air in gas-phase and as sorbet to aerosols. Atmospheric partitioning of PAH compounds between the particulate and the gaseous phases strongly influences their fate and transport in the atmosphere and the way they enter into human body. The removal of PAHs from the atmosphere by dry and wet deposition processes are strongly influenced by their gas/particle partitioning. Atmospheric deposition is a major source for PAHs in soil. Many PAHs have toxic, mutagenic and/or carcinogenic properties. PAHs are highly lipid soluble and thus readily absorbed from the gastrointestinal tract of mammals. They are rapidly distributed in a wide variety of tissues with a marked tendency for localization in body fat. Metabolism of PAHs occurs via the cytochrome P450-mediated mixed function oxidase system with oxidation or hydroxylation as the first step. Several different remediation technologies have been tested in efforts to remove these environmental contaminants. Among them, bioremediation is showing particular promise as a safe and cost-effective option. In spite of their xenobiotic properties, a variety of genera of gram-positive and -negative bacteria, fungi and algae have been isolated and characterized for their ability to utilize PAHs. The aim of this review is to discuss PAHs impact on the environmental and the magnitude of the human health risks posed by such substances. Also contain important information on the concentrations, burdens and fate of polycyclic aromatic hydrocarbons (PAHs) in the atmosphere. The main anthropogenic sources of PAHs and their effect on the concentrations of these compounds in air are discussed. The fate of PAHs in the air, their persistence and the main mechanisms of their losses are presented. Health hazards associated with PAH air pollution is stressed.
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Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants generated primarily during the incomplete combustion of organic materials (e.g. coal, oil, petrol, and wood). Emissions from anthropogenic activities predominate; nevertheless, some PAHs in the environment originate from natural sources such as open burning, natural losses or seepage of petroleum or coal deposits, and volcanic activities. Major anthropogenic sources of PAHs include residential heating, coal gasification and liquefying plants, carbon black, coal-tar pitch and asphalt production, coke and aluminum production, catalytic cracking towers and related activities in petroleum refineries as well as and motor vehicle exhaust. PAHs are found in the ambient air in gas-phase and as sorbet to aerosols. Atmospheric partitioning of PAH compounds between the particulate and the gaseous phases strongly influences their fate and transport in the atmosphere and the way they enter into the human body. The removal of PAHs from the atmosphere by dry and wet deposition processes are strongly influenced by their gas/particle partitioning. Atmospheric deposition is a major source for PAHs in soil. Many PAHs have toxic, mutagenic and/or carcinogenic properties. PAHs are highly lipid soluble and thus readily absorbed from the gastrointestinal tract of mammals. They are rapidly distributed in a wide variety of tissues with a marked tendency for localization in body fat. Metabolism of PAHs occurs via the cytochrome P450-mediated mixed function oxidase system with oxidation or hydroxylation as the first step. Several different remediation technologies have been tested in efforts to remove these environmental contaminants. Among them, bioremediation is showing particular promise as a safe and cost-effective option. In spite of their xenobiotic properties, a variety of genera of gram-positive and -negative bacteria, fungi and algae have been isolated and characterized for their ability to utilize PAHs. The aim of this review is to discuss PAHs impact on the environmental and the magnitude of the human health risks posed by such substances. They also contain important information on concentrations, burdens and fate of polycyclic aromatic hydrocarbons (PAHs) in the atmosphere. The main anthropogenic sources of PAHs and their effect on the concentrations of these compounds in air are discussed. The fate of PAHs in the air, their persistence and the main mechanisms of their losses are presented. Health hazards associated with PAH air pollution are stressed.
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Formaldehyde, an irritant and cacinogent to humans, is one of the most concerning indoor gaseous pollutants because it is often found in buildings and poses a potential health risk to occupants even at a very low concentration level. Chemisorption and catalytic oxidization are two promising methods for indoor formaldehyde removal. This review covers the following aspects of the two formaldehyde removal methods: reaction mechanism, activity test method, materials, performance, and effect of environmental conditions (temperature, relative humidity, concentration level, and velocity) on the removal performance. Results show that a supported noble metal (e.g., Pt) and metal oxide (e.g., MnO2) are the most effective catalysts, but usually require a high temperature for complete decomposition of formaldehyde. An amino group containing activated carbon is the most commonly used chemisorbent. The effect of the noble metal loading and the preparation method of the noble metal catalyst are also discussed. Possible applications in a building HVAC system are discussed along with needed future research.
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Thin films of vanadia–titania with good adhesion to the substrates have been deposited on various substrates such as glass slides, glass helix and silica raschig rings by simple sol–gel dip coating process using vanadium and titanium peroxide gel. The optimum concentration of vanadia in titania for obtaining good uniform viscous gel was found to be 0.5–4wt% beyond which the vanadia particles disturb the gel network, resulting in the formation of a gelatinous precipitate. The films of vanadia–titania as well as the dried powder of the bulk gel were characterized by different characterization techniques. Optical characterization by UV–vis spectrophotometer showed a shift in optical absorption wavelength to the visible region that may be due to the incorporation of vanadia into titania structure. The XRD revealed the formation of anatase phase in pure titania as well as titania with up to 2% vanadia loading, whereas formation of rutile as minor phase along with anatase as major phase was observed at higher vanadia loading. The XRD did not show any peaks of vanadia phase up to 5% vanadia loading indicating either incorporation of vanadia into titania structure or high dispersion of amorphous vanadia on titania support. The pure and vanadia doped TiO2 thin films were evaluated for their photocatalytic activity for degradation of methylene blue as a model pollutant under sunlight. Doping of V2O5 in TiO2 showed an increase in the photo-degradation rate of methylene blue by a factor of 3–6.6 times compared to pure TiO2. The highest rate has been obtained for 4% V2O5-doped TiO2 films. Vanadia doped TiO2 thin films were also found to be very active for photocatalytic degradation of formaldehyde from aqueous solution in sunlight.
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There is an increasing concern about the occurrence of polycyclic aromatic hydrocarbons (PAHs) in the environment as they are ubiquitous in ambient air and some of them are among the strongest known carcinogens. PAHs and their derivatives are produced by the incomplete combustion of organic material arising, partly, from natural combustion such as forest and volcanic eruption, but with the majority due to anthropogenic emissions. The PAH concentration varies significantly in various rural and urban environments and is mainly influenced by vehicular and domestic emissions. The review serves as a database to identify and characterize the emission sources of PAHs and hence various approaches including diagnostic ratio (DR) and principal component analysis (PCA) are discussed in detail. These approaches allow individual PAHs to be associated with their origin sources. The factors that effect PAH emission and estimated emission rate are also discussed in this paper. Although the levels of low molecular weight PAHs are high in vapor phase, most of the probable human carcinogenic PAHs are found to be associated with particulate matter, especially in fine mode particles in ambient air. Many countries have proposed a non-mandatory concentration limit for PAHs, whereas the health risk studies conducted in relation to PAH exposure, urge that these pollutants should be given a high priority when considering air quality management and reduction of impacts.
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The depleting natural resources, primarily petroleum that has been the backbone of fuel industry is finding itself at loss to answer the questions of our future needs. This has led researchers to venture into the area of biodiesel since it is the next best contender to replace diesel in the immediate future. This is so because biodiesel has characteristics not only similar to diesel but also better in many respects, like biodegradability, renewability and better emission characteristics. Many authors have studied regulated emission characteristics. The results are in favour of biodiesels in terms of carbon monoxide, smoke, hydrocarbons (HC) and particulate matter (PM). The study in the area of unregulated emissions is, however, limited and inconsistent, even though they are considered carcinogenic and mutagenic in nature. Hence, for a better understanding of biodiesel and their emissions, it is necessary to examine their unregulated emissions as well. This paper consolidates and analyses data regarding carbonyl, polyaromatic hydrocarbons (PAHs) and their oxy and nitro derivatives of various biodiesels derived from various feedstock and their diesel and alcohol blends. The emission trends have also been studied for various parameters like engine speed, engine load, driving cycle etc.
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Diesel engine emissions consist of several harmful gaseous species, some of which are regulated by stringent emission norms, while many others are not. These unregulated emission species are responsible for adverse environmental impact and serious health hazards upon prolonged exposure. In this study, a four-cylinder, 1.4 l, compression ignition (CI) engine was used for characterization of unregulated gaseous exhaust emissions measured at 2500 rpm at varying engine loads (0, 25, 50, 75 and 100%). The test fuels investigated were Karanja biodiesel blended with diesel (KB5, KB20), methanol blended with diesel (M5) and baseline mineral diesel. Fourier transform infrared (FTIR) emission analyzer was used to measure unregulated emission species and raw exhaust gas emission analyzer was used to measure regulated emission species in exhaust. Results show an increasing trend for some of the unregulated species from blends of biodiesel such as formaldehyde, acetaldehyde, ethanol, n-butane however methane reduced upon using these oxygenated fuel blends except methanol, compared to baseline mineral diesel. Nevertheless, no significant changes were observed for sulfur dioxide, iso-butane, n-octane, n-pentane, formic acid, benzene, acetylene and ethylene upon using biodiesel and methanol blends.
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Gases, aerosols and particles associated with atmospheric contamination may be classified in two broad categories - "conventional' and "greenhouse' pollutants. Conventional pollutants include the immediately harmful constituents of automotive emissions such as carbon monoxide, nitrogen oxides, nonmethane hydrocarbons, sulfur oxides, suspended particulate matter and lead. Greenhouse pollutants include emissions of carbon dioxide, methane, nitrous oxide and chlorofluorocarbons. These emissions have significant health and welfare impacts, which may be disaggregated at three levels, "local', "regional' and "global'. While these effects have been observed universally, the air pollution problem in developing countries has not been adequately evaluated and documented. This paper attempts to assess the share of developing countries in pollutant emissions from motor vehicles, particularly the implications for urban air quality. -from Author
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In this study, we selected four unregulated emissions species, formaldehyde, benzene, 1,3-butadiene and benzo[a]pyrene to research the emission characteristics of these unregulated components experimentally. The engine used was a water-cooled, 8-liter, 6-cylinder, 4-stroke-cycle, turbocharged DI diesel engine with a common rail fuel injection system manufactured for the use of medium-duty trucks, and the fuel used was JIS second-class light gas oil, which is commercially available as diesel fuel. The results of experiments indicate as follows: formaldehyde tends to be emitted under the low load condition, while 1,3-butadiene is emitted at the low engine speed. This is believed to be because 1,3-butadiene decomposes in a short time, and the exhaust gas stays much longer in a cylinder under the low speed condition than under the high engine speed one. Benzene is emitted under the low load condition, as it is easily oxidized in high temperature. Benzo[a]pyrene exists in the gas phase, because its boiling point is about 750K (at 128kPa). Once gaseous benzo[a]pyrene condenses, it is trapped by a filter with soot or sulfate. If it stays in the high temperature area, large part of it is oxidized. Consequently, benzo[a]pyrene is not emitted in great quantity under the high load condition.
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Concern about the toxicity of formaldehyde has increased since the report by the Chemical Industry Institute of Toxicology (Third CIIT Conference on Toxicology, November 1980, Raleigh, North Carolina) that carcinomas were found in animals after exposures to formaldehyde. The present toxicology of formaldehyde is reviewed along with a description of the current toxicological testing methodologies. The most significant properties of the compound are its potential to cause irritation and nasal tumors. Considerations for interpreting the results are discussed.
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VOCs pollution is a complex issue involving a wide variability of pollutants that threatens human health and environment. Owing to the effective and economic characters, low-temperature (293–673 K) catalytic oxidation (CO) has been extensively studied for VOCs removal in research and application fields. This review examines recent progress on the VOCs catalytic oxidation with noble metal and metal oxides catalysts, and the engineering features of regenerative catalytic oxidizer (RCO), recuperative catalytic oxidizer (CO), photocatalytic oxidizer (PCO) and hybrid treatment combining adsorptive concentration/ozonation/plasma with catalytic oxidizer. The aim was to analyze the factors that relate to the low-temperature activity of catalysts, and the efficiency and economy of manifold catalytic oxidizers. It can be concluded that improving low-temperature activity of catalysts, increasing thermal recovery efficiency of oxidizers and developing hybrid treatment technologies are most effective means to control practical VOCs pollution.
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Background: Indoor air pollution is associated with decreased pulmonary function but the relative impact of pollution from kitchen sources on health risks in kitchen workers is not well-known or studied. A study was conducted to measure the kitchen indoor air quality including PAHs estimation and risk assessment based on reported PAHs in indoor air in a central kitchen at North India. Methods: A cross sectional study was undertaken to assess the lung function status using spirometer and urinary PAH metabolite measurements using GC-MS/MS among 94 male kitchen workers and their corresponding controls. Assessment of the indoor air quality levels was evaluated using standard methods. Results: All the indoor air pollutants were within the recommended guidelines except CO, TVOC and PAH emission in the kitchen. Incremental life time cancer risk (ICLR) based on indoor air PAH measurements indicates potential for carcinogenic risk. Significant lung function decline was observed among kitchen workers as compared to controls after adjusting for smoking habits. Urinary PAH metabolites were detected in kitchen workers and measured concentrations were comparatively higher than control subjects. Conclusion: The decline in lung functions after adjustment for confounders and detection of urinary PAH metabolites in kitchen workers can be associated with higher concentrations of PAHs, CO and TVOCs in kitchen indoor air.
Article
A Pt@TiO2 core–shell material was prepared by a reverse micelle sol–gel method to develop an efficient photocatalyst for the degradation of formaldehyde (HCHO). The properties of the photocatalytic materials were analyzed with UV–vis spectra, X-ray diffraction spectra, energy-dispersive X-ray spectroscopy, transmission electron microscopy, and BEL-MINI adsorption analyzer. Photocatalytic capabilities of photocatalytic materials were investigated in degradation of formaldehyde in presence of visible light irradiation. The experimental result indicates that the Pt@TiO2 nanoparticles achieved 98.3% formaldehyde degradation, while TiO2 (P25), TiO2 (home made), and 1 wt% Pt/TiO2 (home made) achieved 92.4%, 75.2%, and 85.6% respectively. Thus, the Pt@TiO2 displayed excellent formaldehyde degradation efficiency. In addition, Pt@TiO2 can be used repeatedly without significantly changing their formaldehyde degradation capacities. Therefore, the Pt@TiO2 core–shell material has potential as a promising application in the field of formaldehyde degradation.
Article
There are more than 350 oil-bearing crops identified as potential sources for biodiesel production around the globe. The wide range of available feedstocks for biodiesel production represents one of the most significant factors for producing biodiesel. The current research work is carried out on fuel properties of biodiesel prepared from the non-edible oils of Ceiba pentandra, Nigella sativa and their mixture. N. sativa is believed to be investigated for the first time as a biodiesel feedstock while C. pentandra has been reported recently in few studies. Owing to higher acid value, acid-esterification and alkali-transesterification processes have been carried out for biodiesel production. The fuel properties of C. pentandra methyl ester(CPME), N. sativa methyl ester (NSME) and their feedstock mixture (NSME/CPME) are determined. It has been found that the produced biodiesel from respective feedstocks matches the properties set by ASTM6751 standards. However, the fuel properties of the C. pentandra biodiesel exhibited better calorific value,viscosity and flash point while N. sativa exhibited excellent cold flow properties and oxidation stability.
Article
As a main indoor air pollutant, formaldehyde was chosen as the aim pollutant. Nano-structured TiO2, Ag–TiO2 and Ce–TiO2 thin films were prepared by sol–gel method at room temperature and used in the photo-catalyst reactor for HCHO decomposition. The effects of doped Ag/Ce/TiO2, relative humidity, oxygen concentration, initial HCHO concentration, UV light wavelength, TiO2 amount on HCHO decomposition were investigated. The results showed that doped Ag or Ce ions could enhance the photo-catalyst ability. 35% was the optimal humidity for photo-catalyst process under the experimental conditions. Higher concentration of oxygen was better for HCHO removal. Photo-catalytic degradation rates decreased with increasing HCHO initial concentration. Illumination using a 254 nm light source was better than 365 nm. The photo-catalytic degradation efficiency increased with the increasing the amount of TiO2 when TiO2 amount was lower than 70 mg. The reaction rate constant (k) of TiO2, Ag/TiO2, Ce/TiO2 was sequenced kCe/TiO2 > kAg/TiO2 > kTiO2, meaning that Ce/TiO2 had the best photo-catalytic ability among the catalysts.
Article
Tailpipe and evaporative emissions from three pre-1985 passenger motor vehicles operating on an ethanol oxygenated and on a nonoxygenated (base) fuel were characterized. Emission data were collected for vehicles operating over the Federal Test Procedure at 90 °F, 75 °F, and 40 °F to simulate ambient driving conditions. The two fuels tested were a commercial summer-grade regular gasoline (the nonoxygenated base fuel) and an oxygenated fuel containing 8.8% ethanol, more paraffins and olefins, and less aromatics than the base fuel. The Reid vapor pressure (RVP) was adjusted to correspond to that of the base fuel. The emissions measured were total hydrocarbons (THCs), speciated hydrocarbons, spedated aldehydes, carbon monoxide (CO), and oxides of nitrogen (NOX).This study showed a general reduction in tailpipe emissions of THC, CO, benzene, and 1,3-butadiene when tested with the ethanol fuel. The ethanol fuel significantly reduced these emissions from the high emitting vehicle, MU098, at 90 °F, 75 °F, and 40 °F test temperatures. Additionally, the ethanol fuel reduced CO emissions from vehicle BU950, with and without catalyst, and from vehicle CI415 at 40 °F. Both formaldehyde and acetaldehyde emissions generally increased when tested with the oxygenated fuel. The acetaldehyde emissions were about double with this fuel. The limited data indicate that most emissions, including toxics, occur during the first 124 seconds of vehicle start-up.Diurnal evaporative emissions were less from the oxygenated fuel, while hot-soak evaporative emissions were greater from the oxygenated fuel (for all vehicles except MU098). Evaporative emissions were generally greatest at the 90 °F test temperature.
Article
Interest in use of biodiesel fuels derived from vegetable oils or animal fats as alternative fuels for petroleum-based diesels has increased due to biodiesels having similar properties of those of diesels, and characteristics of renewability, biodegradability and potential beneficial effects on exhaust emissions. Generally, exhaust emissions of regulated pollutants are widely studied and the results favor biodiesels on CO, HC and particulate emissions; however, limited and inconsistent data are showed for unregulated pollutants, such as carbonyl compounds, which are also important indicators for evaluating available vehicle fuels. For better understanding biodiesel, this study examines the effects of the biodiesel blend fuel on aldehyde chemical emissions from diesel engine exhausts in comparison with those from the diesel fuel. Test engines (Mitsubishi 4M40-2AT1) with four cylinders, a total displacement of 2.84L, maximum horsepower of 80.9kW at 3700rpm, and maximum torque of 217.6Nm at 2000rpm, were mounted and operated on a Schenck DyNAS 335 dynamometer. Exhaust emission tests were performed several times for each fuel under the US transient cycle protocol from mileages of 0–80,000km with an interval of 20,000km, and two additional measurements were carried out at 40,000 and 80,000km after maintenance, respectively. Aldehyde samples were collected from diluted exhaust by using a constant volume sampling system. Samples were extracted and analyzed by the HPLC/UV system. Dominant aldehydes of both fuels’ exhausts are formaldehyde and acetaldehyde. These compounds together account for over 75% of total aldehyde emissions. Total aldehyde emissions for B20 (20% waste cooking oil biodiesel and 80% diesel) and diesel fuels are in the ranges of 15.4–26.9mgbhp-h−1 and 21.3–28.6mgbhp-h−1, respectively. The effects of increasing mileages and maintenance practice on aldehyde emissions are insignificant for both fuels. B20 generates slightly less emission than diesel does. Major difference in both fuels is formaldehyde emission which drops by 23% on the average. Lower aldehyde emissions found in B20 correspond to lower ozone formation potentials. As a result, use of biodiesel in diesel engines has the beneficial effect in terms of aldehyde emissions.
Article
Complete oxidization of formaldehyde into harmless water and carbon dioxide was obtained over Ag/MnOx–CeO2 catalysts at a temperature as low as 373K. Structural analysis by X-ray powder diffraction (XRD), X-ray photoelectron spectra (XPS) and temperature-programmed reduction (TPR) measurements revealed that the formation of MnOx–CeO2 solid solution and the subsequent addition of silver species resulted in significant improvement in the effective activation of oxygen molecules in the reaction stream. Accordingly, a consecutive oxygen transfer mechanism starting from the oxygen reservoir of CeO2 to active Ag2O sites through MnOx was proposed. The oxygen species released from the decomposition of Ag2O participated in the oxidation of formaldehyde, and the reoxidation of Ag to Ag2O was achieved through the oxygen species from MnO2. Simultaneously, the transformation of the produced Mn2O3 to MnO2 was realized by the oxygen species from the oxygen reservoir of CeO2, and the Ce2O3 thus formed can be reoxidized into CeO2 by the oxygen in the feed stream. Such a consecutive oxygen pathway was suggested to play an important role in the complete oxidation of formaldehyde.
Article
Scenarios have been developed and calculations made for aldehyde production from primary and secondary sources within the stable boundary layer after sunset until several hours after sunrise the next day. The sensitivities of production of formaldehyde and several higher molecular weight aldehydes from alkenes to variations in O3 and NO3 concentrations are estimated. Production of aldehydes from alkenes emitted during the 2100h to 0600h period is calculated within the 2100h to 0600h period and the 0600h to 0900h period. The relative production of the aldehydes from primary vehicular sources relative to secondary atmospheric reactions is considered. The contribution from the OH reactions with alkanes to aldehyde production in the 0600h to 0900h period also is estimated.
Article
Gas- and particle-phase tailpipe emissions from late-model medium duty diesel trucks are quantified using a two-stage dilution source sampling system. The diesel trucks are driven through the hot-start Federal Test Procedure (FTP) urban driving cycle on a transient chassis dynamometer. Emission rates of 52 gas-phase volatile hydrocarbons, 67 semivolatile and 28 particle-phase organic compounds, and 26 carbonyls are quantified along with fine particle mass and chemical composition. When all Câ--Cââ carbonyls are combined, they account for 60% of the gas-phase organic compound mass emissions. Fine particulate matter emission rates and chemical composition are quantified simultaneously by two methods: a denuder/filter/PUF sampler and a traditional filter sampler. Both sampling techniques yield the same elemental carbon emission rate of 56 mg km⁻¹ driven, but the particulate organic carbon emission rate determined by the denuder-based sampling technique is found to be 35% lower than the organic carbon mass collected by the traditional filter-based sampling technique due to a positive vapor-phase sorption artifact that affects the traditional filter sampling technique. The distribution of organic compounds in the diesel fuel used in this study is compared to the distribution of these compounds in the vehicle exhaust. Significant enrichment in the ratio of unsubstituted polycyclic aromatic hydrocarbons (PAH) to their methyl- and dimethyl-substituted homologues is observed in the tailpipe emissions relative to the fuel. Isoprenoids and tricyclic terpanes are quantified in the semivolatile organics emitted from diesel vehicles. When used in conjunction with data on the hopanes, steranes, and elemental carbon emitted, the isoprenoids and the tricyclic terpanes may help trace the presence of diesel exhaust in atmospheric samples.
Article
The adsorption of formaldehyde (HCHO) at very low vapor concentration (zero surface coverage) is studied on several carbon materials by using inverse gas−solid chromatography (IGC). The adsorption process is carried out in the Henry's law region. Therefore, the specific retention volumes, Vs, allow the determination of the standard enthalpy of adsorption, ΔHoA, using the linear relationship between ln Vs vs 1/T. Nevertheless two linear plots are obtained for the adsorption of HCHO on these carbon materials. Several experiments have been designed in order to determine the physical meaning of these linear plots. The general conclusion is that they are produced by a temperature-dependent mechanism which allows the adsorption to occur in smaller pores at lower temperatures and in larger ones at higher temperatures.
Article
Formaldehyde (HCHO) is a typical air pollutant capable of causing serious health disorders in human beings. This work reports plasma-catalytic oxidation of formaldehyde in gas streams via dielectric barrier discharges over Ag/CeO2 pellets at atmospheric pressure and 70 °C. With a feed gas mixture of 276 ppm HCHO, 21.0% O2, 1.0% H2O in N2, ~99% of formaldehyde can be effectively destructed with an 86% oxidative conversion into CO2 at GHSV of 16500 h−1 and input discharge energy density of 108 J l−1. At the same experimental conditions, the conversion percentages of HCHO to CO2 from pure plasma-induced oxidation (discharges over fused silica pellets) and from pure catalytic oxidation over Ag/CeO2 (without discharges) are 6% and 33% only. The above results and the CO plasma-catalytic oxidation experiments imply that the plasma-generated short-lived gas phase radicals, such as O and HO2, play important roles in the catalytic redox circles of Ag/CeO2 to oxidize HCHO and CO to CO2.
Article
Despite their industrial importance, only few experimental studies on distillation of aqueous, methanolic formaldehyde solutions are described in the literature. In the present work, for the first time, results from pilot-scale distillation of mixtures of formaldehyde, water, and methanol are presented. The experiments were carried out in a 250 mm diameter distillation column equipped with 2 m Sulzer BX wire gauze packing. Two variants of that packing were studied: the commercially available type and a modified type with increased specific surface. The column was operated at 1 bar at total reflux. Both the overall feed composition and the fluid dynamic loads were varied systematically in the experiments. Samples were taken above and below the packing bed as well as at one intermediate position. For analysis, the sodium-sulfite method (formaldehyde), gas chromatography (methanol), and Karl–Fischer titration (water) were used. A total of 19 experiments were carried out. The studied formaldehyde distillations are complex reactive processes due to a series of reactions taking place in both phases. The experimental data were successfully modelled with a stage based physico-chemical model for thermal separations of formaldehyde containing mixtures, which was recently developed.
Article
Graphite oxide silylated by 3-aminopropylmethyldiethoxysilane was used an adsorbent of formaldehyde from gas phase at low concentration. The amount of formaldehyde adsorbed on this adsorbent was much higher than that on activated carbon, even when water molecules are preadsorbed. The utility of the amino groups seemed to be higher for the sample with lower contents of organic component between the graphite oxide layers and larger interlayer spacings.
Article
In order to reduce vehicle occupants' exposures to aromatic volatile organic compounds (VOCs), it is necessary to develop control strategies for in-vehicle VOCs. This study evaluated the technical feasibility of the application of TiO 2 photocatalysis for the removal of VOCs present in air at low parts per billion (ppb) concentrations commonly associated with in-vehicle air quality issues. The photocatalytic removal of five target VOCs was investigated: benzene, ethyl benzene, and o-, m-, p-xylenes. Variables tested for the current study included relative humidity (RH), hydraulic diameter (HD) and flow rate (FW). The fixed parameters included contaminant concentration, UV light source, photocatalytic oxidation (PCO) reactor material and the weight of TiO 2 . Under the experimental conditions, the PCO destruction efficiencies were close to 100% for four different RH ranges that cover typical ambient air humidity ranges. The efficiency of PCO was dependent on the HD of the reactor and the stream FW. Some carbon monoxide was formed as a by-product in the oxidation albeit at low levels. © 2002 Elsevier Science B.V. All rights reserved.
Article
The product distributions have been calculated for more abundant alkanes contributing most of the carbon atoms in the alkane fraction of an ambient air hydrocarbon mixture reasonably representative of U.S. emissions. The effects of ambient temperatures on product yields has been calculated for a range of temperatures from 250 to 330 K. The sensitivity of product yields to uncertainties in alkoxy radical process rate constants has been examined with emphasis on uncertainties in decomposition reactions. Chemical lifetimes are estimated at 300 K under summertime conditions for hydrocarbons and for products of alkane photooxidation in the atmosphere. The atmospheric distribution of alkanes and products is evaluated in terms of the extent to which reaction processes are likely to occur in the planetary boundary layer compared to the free troposphere. The calculations predict a substantial effect of temperature on product yields. A large decrease in alkyl nitrate yields and a smaller decrease in ketone yields occur with increasing temperature. The yields of the short-lived, more reactive aldehydes undergo substantial increases with increasing temperature. Lower yields of ketones and higher yields of aldehydes are associated with the use of higher compared to lower decomposition process rate constants. For the type of U.S. hydrocarbon mixture available from measurements, 16 oxygenated products account for more than 60% of the total alkane carbon atoms converted to products, with most of these carbon atoms accounted for by four products. The effects of increased temperature on product reactivity and radical production may also influence O3 production.
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Air quality monitoring was carried out to collect data on the levels of various indoor and ambient air constituents in two cities in Korea (Seoul and Taegu). Sampling was conducted simultaneously indoors and outdoors at six residences, six offices and six restaurants in each city during summer 1994 and winter 1994–1995. Measured pollutants were respirable suspended particulate matter (RSP), carbon monoxide (CO), carbon dioxide (CO2), nitrogen dioxide (NO2), and a range of volatile organic compounds (VOCs). In addition, in order to evaluate the effect of smoking on indoor air quality, analyses of parameters associated with environmental tobacco smoke (ETS) were undertaken, which are nicotine, ultraviolet (UVPM), fluorescence (FPM) and solanesol particulate matter (SolPM). The results of this study have confirmed the importance of ambient air in determining the quality of air indoors in two major Korean cities. The majority of VOCs measured in both indoor and outdoor environments were derived from outdoor sources, probably motor vehicles. Benzene and other VOC concentrations were much higher during the winter months than the summer months and were not significantly greater in the smoking sites examined. Heating and cooking practices, coupled with generally inadequate ventilation, also were shown to influence indoor air quality. In smoking sites, ETS appears to be a minor contributor to VOC levels as no statistically significant relationships were identified with ETS components and VOCs, whereas very strong correlations were found between indoor and outdoor levels of vehicle-related pollutants. The average contribution of ETS to total RSP concentrations was estimated to range from 10 to 20%.