VOC Distribution Research Articles

Retraction Note: Human identification with their VOC distribution through CMS– SEN Model

Retraction Note: Human identification with their VOC distribution through CMS– SEN Model

Unravelling the Factors Influencing Halide Perovskite Based Switchable Photovoltaics

AbstractLead halide perovskites have revolutionized the field of optoelectronics (such as photovoltaics and light emitting diodes) demonstrating extraordinary material properties despite being formed at low temperatures. However, ion migration in the bulk or at the interfaces results in stability issues especially in devices where metal electrodes directly interface with the perovskite film. Utilizing the switchable photovoltaic phenomenon (SPV) in halide perovskites as a measure of ion migration and electrochemical reactions within them, Cs0.05MA0.15FA0.70PbI2.5Br0.5 triple cation perovskite, widely used in photovoltaics is evaluated. The various factors determining the SPV, including electric field magnitudes, type of metal contacts, Illumination conditions, and temperature is systematically measured. This study reveals the roles of electrode work functions and reactivities on ion migration and local electronic structure modulation. ITO electrodes demonstrated the highest open‐circuit voltage (Voc) about 0.85 V while Ag electrodes developed conductive filaments. However, the Voc distribution for Ti and Cr electrodes shows a more pronounced linear correlation with the poling electric field strength. Insights from this lateral design are directly relevant to transistor and memristor architectures and offer inputs into the design of perovskite‐based photovoltaic/optoelectronic devices.

Vertical Distribution Characteristics of Boundary Layer Volatile Organic Compounds in Autumn in the Mixed Industrial and Rural Areas over the Northern Suburb of Nanjing

Based on the sounding data of VOCs in the lower troposphere (0-1000 m) in the northern suburb of Nanjing in the autumn of 2020, the vertical profile distribution, diurnal variation, and photochemical reactivity of VOCs in this area were analyzed. The results showed that the volume fraction of VOCs decreased with the increase in height (72.1×10-9±28.1×10-9-56.4×10-9±24.8×10-9). Alkanes at all heights accounted for the largest proportion (68%-75%), followed by aromatics (10%-12%), halohydrocarbons (10%-11%), alkenes (3%-7%), and acetylene (2%). The diurnal variation of the boundary layer had a great influence on the VOCs profile. The lower boundary layer in the morning and evening caused the volume fraction of VOCs to accumulate near the ground and lower in the upper layer. The vertical distribution of VOCs was more uniform in the afternoon. In the morning, the volume fraction proportion of alkenes (alkanes) with strong (weak) photochemical reactivity decreased (increased) with the increase in height, indicating that the photochemical aging of VOCs in the upper layer was significant. In the afternoon, the vertical distribution of VOCs volume fraction and OFP in the lower troposphere were more uniform. Affected by the surrounding air masses with different sources, the volume fraction and component proportion of VOCs at each height were significantly different. The alkanes in rural air masses were vertically evenly distributed, and the proportion increased gradually with the height. The vertical negative gradient of VOCs volume fraction in the urban air mass was the largest, the volume fraction of VOCs near the ground was high, and it was rich in aromatics. The proportion of aromatics increased with the increase in VOCs volume fraction between 200-400 m height of industrial air mass. The near-surface VOCs volume fraction of the highway traffic air mass was high, and alkanes accounted for the largest proportion.

Study on the Distribution of VOCs in the Ambient Air of Domestic Industrial Complexes using Mobile SIFT-MS

Study on the Distribution of VOCs in the Ambient Air of Domestic Industrial Complexes using Mobile SIFT-MS

Research on pollution characteristics of volatile organic compounds based on the remanufacturing process of automobile gearbox

The automobile gearbox remanufacturing industry adheres to the concept of resource recycling, but its environmental pollution problems are easily ignored. In this study, a total of 54 VOCs were analyzed in the gearbox remanufacturing plant, the distribution of VOCs at different heights was simulated, and emission factors were calculated. Combined with working conditions and sources of pollutants, the correlation between VOCs pollution and the remanufacturing process was analyzed, and relevant suggestions were put forward from the perspective of cleaner production and environmental protection. The results showed that the concentration of VOCs at 3.0 m was higher than that at 1.5 m, and more VOCs were released during cleaning (19.6 mg/m3 at 3.0 m) and sandblasting (15.7 mg/m3 at 3.0 m) than the others. In addition, the monitoring results also reflected that the VOCs in the workshop showed a tendency to accumulate from near ground to higher places. At the same time, the more concentrated VOCs in the closed area were more likely to diffuse to the surrounding semi-open/open areas, or migrate to other areas with the gearbox remanufacturing process. Aromatic organic compounds (MACHs) and volatile halogenated hydrocarbons (VHHs) were the most widely distributed and accounted for the highest overall. Processing agents and lubricating oil were the main source of toluene and dichloromethane. Additionally, remanufacturing a gearbox emitted approximately 25.59 g of VOCs into the environment.

Dual-Resistance of Ion Migration and Moisture Erosion via Hydrolytic Crosslinking of Siloxane Functionalized Poly(Ionic Liquids) for Efficient and Stable Perovskite Solar Cells

Dual-Resistance of Ion Migration and Moisture Erosion via Hydrolytic Crosslinking of Siloxane Functionalized Poly(Ionic Liquids) for Efficient and Stable Perovskite Solar Cells

A Study on the Distribution of Air Pollutants in Petrochemical Industrial Complex On Summer

Objectives : Using a mobile laboratory equipped with Proton Transfer Reaction-Time of Flight/Mass Spectrometry (PTR-ToF-MS), we investigate the degree of air pollution level in the petrochemical industrial complex by investigating the distribution characteristics of air pollutants and tracking emission sources.Methods : The research area within the petrochemical industrial complex was measured three times each at dawn, day, night, and the distribution of VOCs at each time was investigated and presented as a pollution map. In the emission source tracking, hot spot (high-concentration) wes found by mobile monitoring, and the emission source was closely tracked by stationary monitoring.Results and Discussion : Acetaldehyde measured in the petrochemical industrial complex was confirmed to have the highest 3 to 5 degrees by direct olfactory method. In most instances the highest concentration was at dawn, potentially due to stagnant pollutants caused by temperature reversal. It was observed that the probability of finding an hot spot was higher during dawn and that it was significantly affected by the wind direction and speed at the time of measurement. When tracking the emission sources, appropriate areas of concern for contamination were selected on the basis of the stationary monitoring results, which were obtained from areas showing high concentrations after mobile monitoring.Conclusion : As a result of the investigation of the distribution characteristics and emission sources of air pollutants in the petrochemical industrial complex, we found that acetaldehyde was the major pollutant and presented an efficient method to search for areas of concern for air pollution. Through these results, it is expected that emission sources can be managed more efficiently.

Emergence of B.1.1.318 SARS-CoV-2 viral lineage and high incidence of alpha B.1.1.7 variant of concern in the Republic of Gabon

ObjectiveVariants of concern (VOCs) associated with relatively high transmissibility appear to be rapidly spreading in Gabon. Therefore, it is imperative to understand the distribution of several VOCs in the population, which could have implications for transmissibility and vaccine efficacy. MethodsBetween February and May 2021, SARS-CoV-2 genomes were sequenced using the Oxford nanopore MinION method and the respective genome diversity was elucidated. Phylogenetic analysis was performed and genomes were classified using pangolin lineages. ResultsThe results highlighted an increase (46%) in the alpha VOC (B.1.1.7) in the Gabonese population over the study period. In addition, an increase (31%) in the B.1.1.318 lineage, which is associated with high transmission and impaired vaccine efficacy (D614G+E484K+Y144del), was detected. ConclusionWith the second wave ongoing, these findings highlight the need for surveillance of the SARS-CoV-2 genome in the Republic of Gabon and should provide useful guidance to policymakers in selecting an appropriate vaccine for this population.

Source-resolved attribution of ground-level ozone formation potential from VOC emissions in Metropolitan Vancouver, BC

The common regulatory approach for managing ground-level ozone (O3) formation is based upon reducing the emission of total VOC in VOC limited regions, and the emission of NOx in NOx limited regions. However, the characteristic VOC species emitted from different sources are of different ozone formation potentials (OFP). Without an in-depth understanding of the relative OFP contributions from specific sources, the effectiveness of the existing approach for controlling ground-level O3 at the regional scale is limited. This study collected and analyzed five years (2012–2016) of monitoring data for 56 most photochemically reactive VOC species at Port Moody, an industrial city in Metro Vancouver, Canada that has experienced elevated O3 levels in its ambience. Source-specific contributions to OFP were quantified for major VOC emitters to deliberate the underlying causes of elevated O3 recently observed in this populated region.Six sources were identified using the positive matrix factorization (PMF) model, consisting of fuel production and combustion, fuel evaporation, vehicle exhaust, industrial coatings/solvents, petrochemical source, and other industrial emission. Although the top three contributors to total VOCs are fuel production and combustion (34.5%), fuel evaporation (21.4%), and vehicle exhaust (20.6%), the top three contributors to OFP are fuel production and combustion (27.1%), vehicle exhaust (23.7%), and industrial coatings/solvents (17.2%). Additionally, potential source contribution function (PSCF) analysis was conducted to generate the geographical distribution of VOC and OFP sources in different seasons. The results revealed that, in the Metro Vancouver area, the OFP hotspots have been significantly different from the VOC emission hotspots. In general, regional sources, especially those located in the northeastern direction of Metro Vancouver, have greater influence on the VOCs levels. However, OFP has been predominantly affected by transportation and industrial sources at the local scale. Therefore, to formulate effective strategies for reducing ground-level O3, the seasonal and spatial variations of major OFP sources should be assessed by the regulatory authorities.

Monitoring of breath VOCs and electrical impedance tomography under pulmonary recruitment in mechanically ventilated patients

Analysis of exhaled VOCs can provide information on physiology, metabolic processes, oxidative stress and lung diseases. In critically ill patients, VOC analysis may be used to gain complimentary information beyond global clinical parameters. This seems especially attractive in mechanically ventilated patients frequently suffering from impairment of gas exchange. This study was intended to assess (a) the effects of recruitment maneuvers onto VOC profiles, (b) the correlations between electrical impedance tomography (EIT) data and VOC profiles and (c) the effects of recruitment onto distribution of ventilation. Eleven mechanically ventilated patients were investigated during lung recruitment after cardiac surgery. Continuous breath gas analysis by means of PTR-ToF-MS, EIT and blood gas analyses were performed simultaneously. More than 300 mass traces could be detected and monitored continuously by means of PTR-ToF-MS in every patient. Exhaled VOC concentrations varied with recruitment induced changes in minute ventilation and cardiac output. Ammonia exhalation depended on blood pH. The improvement in dorsal lung ventilation during recruitment ranged from 9% to 110%. Correlations between exhaled concentrations of acetone, isoprene, benzene sevoflurane and improvement in regional ventilation during recruitment were observed. Extent and quality of these correlations depended on physico-chemical properties of the VOCs. Combination of continuous real-time breath analysis and EIT revealed correlations between exhaled VOC concentrations and distribution of ventilation. This setup enabled immediate recognition of physiological and therapeutic effects in ICU patients. In a perspective, VOC analysis could be used for non-invasive control and optimization of ventilation strategies.

Study on Species and Distribution of Volatile Organic Compounds in WWTP

This study carried on a qualitative analysis on emission and distribution of VOCs and quantitative analysis on BTEX and chlorinated hydrocarbon emitted from a municipal wastewater treatment plant (WWTP). At the same time, the variations of BETX and chlorinated hydrocarbon in three-phases in the biological treatment process in lab-scale were investigated. Results revealed that the low molecular weight hydrocarbon, BTEX (benzene, toluene, xylene) and chlorinated hydrocarbons (chloroform, carbon tetrachloride, chlorylene, tetrachloroethylene) were the main components of VOCs. Primary clarifier volatilized thirty-three species of VOCs, which was most in the WWTP. The remaining organic compounds in this unit belonged to refractory organics that was hardly decomposed by microbe. The more complex aromatic compounds in VOCs were detected.

Ozone Variations over Central Tien-Shan in Central Asia and Implications for Regional Emissions Reduction Strategies

The variability of total column ozone (TCO) and tropospheric column ozone (TrCO) was examined in Central Asia. Measurements were conducted at the Lidar Station Teplokluchenka in eastern Kyrgyzstan for one year, July 2008–July 2009. TCO was obtained using a handheld Microtops II Ozonometer (TCO-MII) and from the Aura OMI (TCO-OMI) satellite. Nitrogen dioxide (NO2) and formaldehyde concentrations also were obtained from the OMI satellite. Formaldehyde was used as a surrogate for volatile organic compounds. TrCO was estimated by the difference between TCO-OMI and stratospheric column ozone retrieved from the MLS satellite. Comparison of the ground-based TCO-MII with TCO-OMI showed good agreement (r 2 = 0.93), and linear regression between these was used to estimate missing values in the TCO-MII dataset. The contribution of TrCO to TCO varied from 15% in summertime to 5% in winter. High values of TrCO were observed during summer (July: 45 DU) and low values during winter (December: 15 DU), as is typically observed. The average values of TrCO for summer, autumn, winter, and spring were equal to 42, 27, 20, and 30 DU, respectively. Seasonal variability of TrCO corresponded to solar intensity, indicating that TrCO is likely to form through photochemical means rather than stratospheric intrusion. The spatial distribution of NO2 and VOC were examined to better understand the regional sources of these ozone precursors. Transport from highly populated areas of the Ferghana Valley and Tashkent in Uzbekistan contributed to the TrCO concentrations observed in this work. The HCHO/NO2 ratio, an indicator of the ozone production rate, suggested that reducing NO2 would be more effective in reducing TrCO during most of the year, except summer, when reductions of both would likely be needed.

A Long-Term Modelling Study of Ventilation and VOC Distribution in Multi-family Residential Buildings in the Severe Cold Region of China

In this paper, a long-term numerical study which examines the unique airflow pattern and the corresponding VOC distribution within a typical apartment building in the severe cold region of China is described. A VOC model was developed to simulate the time-dependent emission rates with adsorption and desorption. This model was then integrated with COMIS, a multi-zone airflow model. The target VOC for study was benzene. The results show various downward tendencies for benzene concentrations in all the dwellings. In addition, it was found that the season when emission occurs must be taken into consideration. Lastly, a mechanical ventilation strategy was proposed which can guarantee the stability of air-exchange rates and isolate VOC emission sources in each apartment by preventing contaminants from being transported to upper-levels of a building through the stairwell.

Transient Characteristics of VOCs Removal by an Air Cleaner in Association with a Humidifier Combined with Different Ventilation Strategies in an Office

This paper investigated the effects of an air cleaner and ventilation strategies on the removal of VOCs in an office in association with the influence of moisture on the air cleaner performance. Here, a transient three dimensional air flow field and concentration distribution of VOCs emitted from a desk were considered. Commercial software FLUENT 6 was utilised to solve the continuity and momentum equations together with the low Reynolds number k-ε turbulence model. Numerical results showed that both the moisture and ventilation strategies have notable impacts on the VOCs concentration distribution. Cases under stronger ventilation take less time for the VOCs concentration to reach the steady state. But, in the cases with the function of the air cleaner, VOCs could be removed more considerably. The combination of the use of the air cleaner and enhanced ventilation strategies could yield more desirable indoor air quality within a relatively short time. The results showed that moisture can have a slight effect on the performance of the air cleaner, but lower moisture would be helpful to the effectiveness of the air cleaner. Thus, based on this work, suitable concentrations of indoor moisture, together with appropriate ventilation strategies have been recommended for control of indoor air quality.

Simulation of VOC Diffusion of Plastic Packaging in the Vehicle Cabin

VOC emission of plastic packing of automobile instrument panels to be harmful for personnel health, in order to effectively control VOC diffusion, needs to analyze the rule of VOC diffusion in the vehicle. In this paper, multi-component model is used to analyze VOC distribution of instrument panel plastic packaging, and influence of the diffusion time, the running status, the well ventilated mode is investigated. The results show that near the panel imports, VOC diffusion is accelerating, and spread to backward along with the time lapse; the automobile movement has propelled to VOC diffusion; ventilation mode had a greater impact on diffusion too.

Evidence of the impact of deep convection on reactive Volatile Organic Compounds in the upper tropical troposphere during the AMMA experiment in West Africa

Abstract. A large dataset of reactive trace gases was collected for the first time over West Africa during the African Monsoon Multidisciplinary Analysis (AMMA) field experiment in August 2006. Volatile Organic Compounds (VOC from C5–C9) were measured onboard the two French aircrafts the ATR-42 and the Falcon-20 by a new instrument AMOVOC (Airborne Measurement Of Volatile Organic Compounds). The goal of this study is (i) to characterize VOC distribution in the tropical region of West Africa (ii) to determine the impact of deep convection on VOC distribution and chemistry in the tropical upper troposphere (UT) and (iii) to characterize its spatial and temporal extensions. Experimental strategy consisted in sampling at altitudes between 0 and 12 km downwind of Mesoscale Convective Systems (MCS) and at cloud base. Biogenic and anthropogenic VOC distribution in West Africa is clearly affected by North to South emission gradient. Isoprene, the most abundant VOC, is at maximum level over the forest (1.26 ppb) while benzene reaches its maximum over the urban areas (0.11 ppb). First, a multiple physical and chemical tracers approach using CO, O3 and relative humidity was implemented to distinguish between convective and non-convective air masses. Then, additional tools based on VOC observations (tracer ratios, proxy of emissions and photochemical clocks) were adapted to characterize deep convection on a chemical, spatial and temporal basis. VOC vertical profiles show a "C-shaped" trend indicating that VOC-rich air masses are transported from the surface to the UT by deep convective systems. VOC mixing ratios in convective outflow are up to two times higher than background levels even for reactive and short-lived VOC (e.g. isoprene up to 0.19 ppb at 12 km-altitude) and are dependent on surface emission type. As a consequence, UT air mass reactivity increases from 0.52 s−1 in non-convective conditions to 0.95 s−1 in convective conditions. Fractions of boundary layer air contained in convective outflow are estimated to be 40 ± 15%. Vertical transport timescale is calculated to be 25 ± 10 min between 0 to 12 km altitude. These results characterize deep convection occurring over West Africa and provide relevant information for tropical convection parameterization in regional/global models.

Prediction of photocatalytic air purifier apparatus performances with a CFD approach using experimentally determined kinetic parameters

An original methodology to predict space–time concentration distribution of VOC in an enclosed space where a photocatalytic air purifier apparatus is placed is herein presented. This apparatus is specially designed for indoor air treatment. Intrinsic kinetic parameters are first determined in a perfectly mixed batch reactor allowing a direct access to chemical reaction rate with a few experiments. Computational fluid dynamics (CFD) is then used to model fluid flow in the room and calculate space–time concentration of VOC by setting chemical reaction rate as a boundary condition based on kinetic parameters determined in the batch reactor. Experiments and modelling are performed using acetaldehyde which is a common indoor volatile organic compound and titanium dioxide thin film coated on steel performed by a PVD method. Remediation of acetaldehyde is investigated at low concentration levels, in the low ppm range. Prediction of acetaldehyde removal in the enclosed space is then compared with experimental results allowing validation of the methodology.

Degradation of C 2–C 15 volatile organic compounds in a landfill cover soil

The composition of non-methane volatile organic compounds (hereafter VOCs) in i) the cover soil, at depths of 30, 50 and 70 cm, and ii) gas recovery wells from Case Passerini landfill site, (Florence, Italy) was determined by GC-MS. The study, based on the analysis of interstitial gases sampled along vertical profiles within the cover soil, was aimed to investigate the VOC behaviour as biogas transits from a reducing to a relatively more oxidizing environment. A total of 48 and 63 different VOCs were identified in the soil and well gases, respectively. Aromatics represent the dominant group (71.5% of total VOC) in soil gases, followed by alkanes (6.8%), ketones (5.7%), organic acids (5.2%), aldehydes (3.0%), esters (2.6%), halogenated compounds (2.1%) and terpenes (1.3%). Cyclics, heterocyclics, S-bearing compounds and phenols are ≤ 1%. In the wells the VOC composition is characterized by higher concentrations of cyclic (7.6%) and S-bearing compounds (2%) and lower concentrations of O-bearing compounds. The vertical distribution of VOCs in the cover soil shows significant variations: alkanes, aromatics and cyclics decrease at decreasing depth, whereas an inverse trend is displayed by the O-bearing species. Total VOC and CH 4 concentrations at a depth of 30 cm in the soil are comparable, inferring that microbial activity is likely affecting VOCs at a very minor extent with respect to CH 4. According to these considerations, to assess the biogas emission impact, usually carried out on the sole basis of CO 2 and CH 4 emission rates, the physical–chemical behaviour of VOCs in the cover soil, regulating the discharge of these highly contaminant compounds in ambient air, has to be taken into account. The soil vertical distribution of these species can be used to better evaluate the efficiency of oxidative capability of intermediate and final covers.

Patterns of VOC and BTEX concentration in ambient air around industrial sources in Daegu, Korea

Patterns of VOC and BTEX (Benzene, Toluene, Ethylvenzene, and Xylene) distribution at industrial emission sources, proximal residential areas of industrial estates, and ambient air were studied in Daegu, Korea. Daytime and night-time sampling was done at 12 sites and 9 emission sources to provide samples for analyses, using the TO-14 method. Measured BTEX component ratios B/T, T/EB, T/X and EB/X in ambient air were found to be 2.6 g, 11.3 g, 1.0 g and 1.2 g in the residential area; 2.2 g, 11.0 g, 1.0 g and 1.6 g in the commercial area; and 1.0 g, 14.9 g, 1.0 g and 1.3 g in the industrial area. The significant difference observed between the ratios for the residential and commercial areas implies that the two areas have different emission sources. This is also indicated by the significant differences observed between daytime and nighttime BTEX concentrations. Toluene and xylene were detected at very high concentrations, at the sampling sites. This pattern reflects the type of industrial processes and materials that are managed at the emission sources, as well as topographic/climatic factors that impact upon pollutant transport processes in the atmosphere. The BTEX distribution pattern in Daegu is observed to be similar to that of several Asian cities, particularly Hong Kong. These results are useful in the design of emission source control measures for VOCs and BTEX in Daegu.

06/02938 Vertical distribution of VOCs and ozone observed in suburban North CarolinaDas, M. et al. International Journal of Global Environmental Issues, 2006, 6, (2–3), 149–172

06/02938 Vertical distribution of VOCs and ozone observed in suburban North CarolinaDas, M. et al. International Journal of Global Environmental Issues, 2006, 6, (2–3), 149–172