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Volatile organic compound (VOC) pollution has a serious impact on human and urgently needs to be controlled through the development of new methods and catalytic materials. Compared with traditional thermal catalytic oxidation, the synergistic photothermocatalysis is regarded as a green and environmentally friendly strategy for organic compound pollutant removal, which can promote spontaneous heating of the surface of catalysts to achieve thermal catalytic reaction conditions via harvesting light irradiation. In this paper, a monolithic photothermocatalyst was synthesized through coating graphene oxide (GO) and MnOx in turn on a commercially available melamine sponge, where the GO mainly acted as a photothermal conversion layer to heat the catalytically active MnOx. This monolithic catalyst presented excellent photo-induced activity for formaldehyde elimination under ambient conditions (∼ 90% degradation ratio in 20 min for ∼160 ppm initial concentration formaldehyde), and meanwhile possessed a high catalytic durability for multiple cycles. The kinetic study demonstrated that this photothermocatalytic process followed a pseudo-second-order kinetics. Finally, we proposed a possible formaldehyde degradation pathway based on in situ DRIFTS examination.

The utilization of either aqueous or conventional/traditional volatile organic compound-based extraction/product development processes in the pharmaceutical industry has become questionable because of the water solubility limitations of active pharmaceutical ingredients (APIs) and stringent regulatory issues concerning the safety aspect of volatile organic compounds (VOCs). The use of neoteric solvents (nonconventional/nontraditional) is being encouraged during API extraction from whole plants or plant tissues and for during pharmaceutical product development. In this review, we provide an overview of the utilization of four neoteric solvents (supercritical fluids, fluorous solvents, ionic liquids, and deep eutectic solvents) in API extraction and pharmaceutical product development processes. Our review highlights solvent-less or solvent-free reactions, which could replace neoteric solvents in drug development in the future.

The research on the adsorption equilibria, kinetics, and increase in process temperature of the volatile organic compound (VOC) adsorption in porous materials ensures safe production, thereby reducing production costs and improving separation efficiency. Therefore, it is critical in predicting the entire adsorption process based on minimal or no experimental input of the adsorbate and adsorbent. We discuss, in this review, the factors that affect the adsorption performance of VOCs in activated carbons, including the adsorption equilibrium, adsorption kinetics, and exotherm during adsorption. Subsequently, the existing prediction models are summarized and compared concerning the adsorption equilibrium, adsorption kinetics, and exothermic process of adsorption. We then propose a new prediction model based on intermolecular interaction and provide an outlook toward the design and manipulation of efficient adsorbents for the VOC system.

The eastern region is an important economic hinterland and energy region of China; however, the rapid economic development and the decoupling of environmental pressure have resulted in a significant increase in volatile organic compound (VOC) emissions, and the region is facing the air pollution problem of high-concentration formaldehyde accumulation. The Aura/Ozone Monitoring Instrument (OMI) remote sensing satellite can perform long-term and large-scale dynamic monitoring of tropospheric formaldehyde, and its data can reflect the distribution of formaldehyde column concentration in the study area. This article discusses the spatial and temporal characteristics of formaldehyde in eastern China from 2009 to 2018 based on OMI's formaldehyde column concentration data daily products. In addition, based on the Multi-resolution Emission Inventory for China (MEIC), the potential contributions of natural sources (isoprene) and anthropogenic sources (industrial sources, transportation sources, and residential sources) to formaldehyde are analyzed. The results show that the formaldehyde column concentration is higher in eastern China, and the high-value areas are mainly concentrated in regions with close human activities, such as Jing-Jin-Ji (JJJ), the Yangtze River Delta (YRD), and the Pearl River Delta (PRD), and the concentration is predicted to increase slowly in the future. One of the main sources of formaldehyde is isoprene emitted by plants, but the impact of human activities on formaldehyde cannot be ignored. The OMI data can objectively reflect the spatiotemporal distributions and change characteristics of formaldehyde in large areas and effectively characterize the accumulation of atmospheric pollutants; thus, the use of OMI can provide an important theoretical basis and reference value for the improvement of regional ecological environment and atmospheric quality.

The detection of volatile organic compound (VOC) mixtures is crucial in the medical and security fields. Receptor-based odorant biosensors sensitively and selectively detect odorant molecules in a solution; however, odorant molecules generally exist as VOCs in the air and exhibit poor water solubility. Therefore, techniques that enable the dissolution of poorly water-soluble VOCs using portable systems are essential for practical biosensors’ applications. We previously proposed a VOC dissolution method based on water atomization to increase the surface area via the generation of fine bubbles, as a proof-of-concept; however, the system was lab-based (non-mobile) and the dissolution was limited to one VOC. In this study, we established a highly effective VOC dissolution method based on mist atomization that can be used in the field. This new method demonstrated a rapid dissolution potential of a sparsely-soluble VOC mixture with various functional groups in distilled water (DW) within 1 min, without the use of any organic solvents. Calcium imaging revealed that odorant receptor 13a-expressing Sf21 cells (Or13a cells) responded to 1-octen-3-ol in the mixture. Further, we successfully developed a field-deployable prototype vacuum and dissolution system with a simple configuration that efficiently captured and rapidly dissolved airborne 1-octen-3-ol in DW. This study proposes a field-deployable system that is appropriate for solubilizing various airborne odorant molecules and therefore is a practical strategy to use in the context of odorant biosensors.

Volatile organic compounds (VOCs) are major contributors to air pollution. Based on the emission characteristics of 99 VOCs that daily measured at 10 am in winter from 15 December 2015 to 17 January 2016 and in summer from 21 July to 25 August 2016 in Beijing, the environmental impact and health risk of VOC were assessed. In the winter polluted days, the secondary organic aerosol formation potential (SOAP) of VOC (199.70 ± 15.05 μg/m3) was significantly higher than that on other days. And aromatics were the primary contributor (98.03%) to the SOAP during the observation period. Additionally, the result of the ozone formation potential (OFP) showed that ethylene contributed the most to OFP in winter (26.00% and 27.64% on the normal and polluted days). In summer, however, acetaldehyde was the primary contributor to OFP (22.00% and 21.61% on the normal and polluted days). Simultaneously, study showed that hazard ratios and lifetime cancer risk values of acrolein, chloroform, benzene, 1,2-dichloroethane, acetaldehyde and 1,3-butadiene exceeded the thresholds established by USEPA, thereby presenting a health risk to the residents. Besides, the ratio of toluene-to-benzene indicated that vehicle exhausts were the main source of VOC pollution in Beijing. The ratio of m-/p-xylene-to-ethylbenzene demonstrated that there were more prominent atmospheric photochemical reactions in summer than that in winter. Finally, according to the potential source contribution function (PSCF) results, compared with local pollution sources, the spread of pollution from long-distance VOCs had a greater impact on Beijing.

In order to address the uneven flow velocity of catalytic reactors and to solve problems such as wear and soaring temperatures in catalysts, a three-dimensional mathematical model of a catalytic reactor was established. A comparison of the physical model and the simulation results revealed that the experimental results were a good fit to the mathematic model. The optimization results revealed the following: advantageous placement of the catalyst was 12.5–17.5 mm from the optimization site; the cross plate + porous plate was preferential; and the area-weighted uniformity index reached 0.93. When the catalyst was placed 25–30 mm from the optimization site, the cross plate + strip plate + hole or cross + grid + plate was preferential and the area-weighted uniformity index reached 0.93.

Accurate and gridded emission inventories are crucial for better air quality modeling and air pollution policy making. As the economic center of the Shandong province and part of the first batch of open coastal cities in China, Qingdao has been frequently plagued by volatile organic compound (VOC) pollution along with its rapid economic development and urbanization in recent years. In this study, a high spatiotemporal resolution VOC emission inventory for Qingdao was established for the year 2016 using updated source-specific emission factors and the latest activity data for different sources. The anthropogenic sources considered in this study are classified into seven major sources and 46 subcategories. The results indicated that a total of 151.5 kt of VOCs were emitted in Qingdao in 2016. The three largest emission sources, industrial process, on-road mobile, and solvent use sources accounted for 49.9% 20.1%, and 14.1% of the total VOC emissions, respectively. Spatially, the Huangdao District (57.9 kt), the Chengyang District (15.4 kt), and Pingdu City (15.1 kt) were the top three emitters of VOCs. The high concentration of VOCs was mainly distributed in the central areas of Qingdao city and the emissions distribution was highly consistent with its road network. The maximum monthly VOC emissions occurred in June (14.4 kt) and the minimum monthly VOC emissions occurred mainly in February (9.5 kt). The uncertainties in the emission inventory were quantified using a Monte Carlo simulation provided by the Oracle Crystal Ball software. There exist relatively high uncertainties in the on-road mobile (-84.79%, 252.07%), biomass burning (-65.38%, 134.77%) and industrial process (-36.08%, 133.62%) sources. For the complicated species and different reaction rates of ozone formation, the control of the amount of VOCs emitted and the highly reactive VOCs are equally important. Based on the emissions of individual VOC species and the corresponding maximum incremental reactivity (MIR), the ozone formation potential (OFP) profiles of Qingdao City were constructed. The results indicated that alkenes/alkynes and aromatics contributed the most to the OFP and that m/p-xylene, ethylene, propylene, formaldehyde, toluene, trans-2-butene, cis-2-butene, 1-butene, o-xylene, and 1-pentene were the top 10 individual VOC species contributing to the OFP. The contribution of industrial process and on-road mobile sources accounted for 37.5% and 24.5% of the total OFP in Qingdao City, respectively. Both the large VOC emission and OFP indicate that the focus of VOC emission control should be on industrial process and on-road mobile sources in Qingdao City.

In this work, the previously developed techno-economic framework in Kong et al. (2018) is extended to evaluate three different configurations of DRIZO process for natural gas dehydration: Case (i) – recycling of the regenerator overhead, Case (ii) – recycling of the flash vapour, and Case (iii) – recycling of both the flash vapour and the regenerator overhead into the dehydration system. The best configuration of DRIZO process is Case (iii), which is used as a representative case for subsequent comparison against other dehydration processes evaluated in our previous work. Our techno-economic analysis reveals that Case (iii) can regenerate tri-ethylene glycol (TEG) with the highest purity and the lowest TEG loss rate and volatile organic compound (VOC) emission. This translates to the lower water content in the dry product gas and also the higher HHV relative to Case (i) and Case (ii). A higher HHV generally signifies a higher gross profit margin. Nevertheless, DRIZO process is not economically feasible in comparison to the other dehydration processes from our previous work, mainly because of the high capital expenditure and the associated operating cost. Relative to the other dehydration processes, although the gross profit margin for DRIZO process is about $100,000 higher, it is not sufficient to compensate the high capital and operating expenses due to the high TCOP of about $500,000 to $600,000. Therefore, our analysis recommends the use of stripping gas dehydration process that consumes a portion of dry product gas to achieve the desired water dew point specification for its highest gross profit margin. Keywords: Dehydration, Glycol regeneration, Natural gas, Tri-ethylene glycol, Aspen HYSYS, Techno-economic analysis

Air pollution a potential environmental problem is caused mostly by the burning of fuels both in the transport sectors and industrial sectors. Motor vehicles are one of the significant growing air pollution contributors who produce a considerable amount of volatile organic compounds (VOCs) and other pollutants. The rising concern about the environmental effect of the exhaust emission pollutants has led to the need for the development of progressively efficient catalytic converters and exhaust gas after-treatment systems. Mathematical modeling is an essential way to understand the processes occurring in the catalytic converter, and it plays a critical part in improving and designing the existing models. A mathematical model has been formed for both non-catalytic and catalytic reactions based on mass and heat transfer for the oxidation of VOC ethane. Modeling equations have been solved with an implicit scheme, and numerical calculations have carried out using Matlab software. The results have been compared, obtained from the two reactions mechanisms.

Formaldehyde (HCHO) being an oxygenated Volatile Organic Compound (VOC), essentially contributes to the hazardous tropospheric ozone pollution in urban areas. Emissions from automobiles are the major contributors towards elevated formaldehyde concentrations in major urban cities of Pakistan. The current study is designed to explore the formaldehyde columns at a stationary site, Institute of Environmental Science and Engineering (IESE), National University of Science and Technology (NUST) Islamabad from September 2015 to August 2017 using Multi-Axis – Differential Optical Absorption Spectroscopy (MAX-DOAS). Observations from MAX-DOAS instrument were used to measure the diurnal, weekly and annual cycle of formaldehyde (HCHO). The diurnal concentrations of HCHO were found to be at its maximum during early morning and evening hours. Relatively insignificant weekly cycle with higher concentrations on working days and lesser during the weekend was observed at IESE-NUST monitoring site. While annual cycle showed the highest columns in summer followed by spring, autumn and winter. The suspected sources of HCHO at a fixed station were identified as natural gas consumption, biogenic emissions from vegetation, emissions from industries and vehicular emissions. Furthermore, ground-based measurements were compared with monthly Ozone Monitoring Instrument (OMI) satellite observations. A good correlation with Pearson value of 0.68 is noticed during the whole study period.

Pollutants present in the exhaust gases coming out from the motor vehicles engine are reduced by passing them through catalytic converters thereby decreasing air pollution considerably. In order to improve the design of the catalytic converters, mathematical modeling and numerical simulation helps not only to reduce the number of experiments but is also time saving. In this paper, a one-dimensional model for volatile organic compound (VOC) was developed using combination of chemical reaction, the heat and mass transfer between the exhaust gas and the catalytic surface. The modeled equations for the converter comprised of a set of coupled partial differential equations which are solved using the backward implicit method. The variation of solid temperature along the axial length and effect of varying the catalyst loading and inlet gas temperatures on the conversion of the VOC was analyzed using Pt/δ-Al2O3 catalyst.

Botanical filtration is a biological-based treatment method suitable for removing hazardous volatile organic compounds (VOCs) from air streams, based on forcing an air flow through a porous substrate and foliage of a living botanical compartment. The pathways and removal mechanisms during VOC bioremediation have been largely investigated; however, their mathematical representation is well established only for the non-botanical components of the system. In this study, we evaluated the applicability of such a modelling scheme to systems which include a botanical compartment. We implemented a one-dimensional numerical model and performed a global sensitivity analysis to measure the input parameters influence on the transient and steady biofilter responses. We found that the most sensitive parameters on the transient-state behaviour were the mass transfer coefficient between gas and solid surfaces, and the fraction of solid surfaces covered by the biofilm; the steady-state response was primarily influenced by the biofilm specific surface area and the fraction of surfaces covered by the biofilm. We calibrated the identified set of parameters and successfully validated the model against data from a pilot-scale installation. The results showed that the application of the model to systems with a botanical compartment is feasible, although under a strict set of assumptions.

With the increase in demand for bio-based coatings with lower volatile organic compound (VOC) emissions, methacrylated cardanol (MACO) and triethoxysilane-functionalized cardanol (TSCO) have been investigated as bio-based reactive diluents for formulating alkyd coatings as a substitute for volatile solvents. The viscosity of the representative alkyd resin was significantly reduced through the use of cardanol-based reactive diluents (over 84% diluent efficiency at 30 wt% loading). Both MACO and TSCO were able to participate in the cross-linked network of the alkyd coating as confirmed by the gel content and cross-link density of the cured coating films. Moreover, the cross-link density of the alkyd coating was significantly improved by using TSCO as the reactive diluent, leading to a significant enhancement in mechanical strength and solvent resistance of the alkyd coating. This work will facilitate the adoption of cardanol as a renewable building block in the coating industry in order to produce greener alkyd coatings.

We report the detection of volatile organic compound 1-cyclohexyl-2-pyrrolidone (CHP), in a bioelectrochemical system inoculated with Escherichia coli and supplemented with redox mediator 2-hydroxy-1,4-naphthoquinone (2-HNQ), using a functionalized carbon nanotube-coated screen-printed electrode (CNT-SPE) modified with –COOH and -NH2 functional groups. Addition of CHP decreased current output of the bioelectrochemical system, thus enabling rapid detection of CHP concentration. Under optimal conditions, the H2N-CNT-SPE was the best performing and a limit of detection (LOD) of 0.4 mg L−1 was achieved. The proposed sensor showed low interference from other inorganic and organic components. These results outline a viable strategy for detecting organic contaminants in environmental monitoring applications.

Formaldehyde (HCHO) still remains the predominant pernicious volatile organic compound (VOC), endangering human health particularly in the room, thus its efficient elimination is of great importance to guarantee indoor air quality. It is highly desirable but challenging to fabricate robust catalyst for complete oxidative HCHO removal at room temperature without secondary pollution. In this report, Au decorated cobalt(Co)-doped Mg/Al layered double hydroxide (x%Au/Co-LDH) were prepared by in-situ deposition of uniform Au nanoparticles on preformed Co-LDH nanosheets. The x%Au/Co-LDH catalyst with optimized loading amount of 2 wt% (2%Au/Co-LDH) exhibited superior activity for complete oxidation of indoor HCHO into CO2, relative to the binary 2%Au/LDH sample without Co-doping and other control samples. Based on the systematic characterizations, it was suggested that the synergetic contributions from the Co-doping, decorated Au NPs, and abundant hydroxyl groups accounted for the effective oxidative HCHO removal over 2%Au/Co-LDH at ambient temperature. In particular, it was proposed that Co-doping favored the Au deposition on Co-LDHs with strong electronic interaction, which would be beneficial for oxygen adsorption and activation at room temperature. This study will not only be contributive for further development of novel catalysts towards effective catalytic HCHO oxidation at room temperature, but also provide new insights into the oxidative HCHO removal mechanisms.

Severe PM2.5 (particulate matter with aerodynamic diameter smaller than 2.5 μm) pollution in China, with adverse impact on human health and global climate change, has raised great concern in recent years. The volatile organic compound (VOC) is suggested to be a significant precursor of PM2.5, but which VOC structure contributes the most to the aerosol particulate formation is still an open question. With large space occupation and complex structures (cyclic, linear and branched), VOCs together with inorganics may play a critical role in atmospheric new particle formation (NPF). To explore the effect of molecular structure on nucleation in NPF, a multi-component (H2SO4-HNO3-NH3-VOC) kinetic model is established based on the gas kinetic theory and graph theory. As the most common VOCs in the atmosphere, alkanes with 2–15 carbons are selected for model analysis. The results show that alkanes especially those with a cyclic structure or carbon number ≥4 results in the highest rate of NPF within the species considered in this study. The dominant size of nuclei, as well as the concentration of particles (larger than 1 nm), is enhanced by the increasing carbon number in alkanes. Taking the alkanes with same carbon number for comparison, the contribution to the nucleation by molecular structure is found to follow the order cyclic>linear>branched, and inversely proportion to branching number.

To evaluate the potential benefits of biomass use for air pollution control, this paper identified and quantified the emissions of major reactive organic compounds anticipated from biomass-fired industrial boilers. Wood pellets (WP) and straw pellets (SP) were burned to determine the volatile organic compound emission profiles for each biomass-boiler combination. More than 100 types of volatile organic compounds (VOCs) were measured from the two biomass boilers. The measured VOC species included alkanes, alkenes and acetylenes, aromatics, halocarbons and carbonyls. A single coal-fired boiler (CB) was also studied to provide a basis for comparison. Biomass boiler 1 (BB1) emitted relatively high proportions of alkanes (28.9%–38.1% by mass) and alkenes and acetylenes (23.4%–40.8%), while biomass boiler 2 (BB2) emitted relatively high proportions of aromatics (27.9%–29.2%) and oxygenated VOCs (33.0%–44.8%). The total VOC (TVOC) emission factors from BB1 (128.59–146.16 mg/kg) were higher than those from BB2 (41.26–85.29 mg/kg). The total ozone formation potential (OFP) ranged from 6.26 to 81.75 mg/m3 with an average of 33.66 mg/m3 for the two biomass boilers. The total secondary organic aerosol potential (SOAP) ranged from 61.56 to 211.67 mg/m3 with an average of 142.27 mg/m3 for the two biomass boilers. The emission factors (EFs) of TVOCs from biomass boilers in this study were similar to those for industrial coal-fired boilers with the same thermal power. These data can supplement existing VOC emission factors for biomass combustion and thus enrich the VOC emission inventory.

Monoterpenes play important roles in atmospheric chemistry and g lobal warming, and their sources and sinks have been investigated. However, there is no information about monoterpene concentrations in black spruce (Picea mariana) forest soil. Here, we investigated seasonal and spatial variations of monoterpene concentrations in soil of an upland black spruce stand in interior Alaska. The site comprised three plots with different tree biomasses, organic layer depths, and vegetation types (mosses and lichens). At each plot, monoterpene concentrations in air in the atmosphere, the soil, and the organic layer under various vegetation types (including leaf litter) were determined. Nine monoterpenes were identified: α-pinene, camphene, β-pinene, 3-carene, sabinene, myrcene, p-cymene, limonene, and β-phellandrene. The total monoterpene concentration in the atmosphere was

Recent literature has shown that volatile organic compound (VOC) emission inventories for urban regions may be substantially underestimated. In particular, non-transportation sources including volatile chemical products (VCP) are increasing in relative importance due to both the current and historical focus on controlling transportation emissions. These findings have major implications for photo-chemical air quality modeling used to determine appropriate and effective regulatory controls to meet limits for primary and secondary pollutants. Using a regional air quality model, we quantify the changes in ozone and fine particulate matter (PM2.5) simulated for updated VOC emissions reported in the recent literature relative to a baseline inventory for California. Results show that simulated maximum 8-hr ozone concentrations could increase by 17.4 ppb in summer and by 15.6 ppb in winter, and the 24-hr maximum PM2.5 could increase by 7.8 μg/m3 in winter. Impacts reflect differences in the spatial location of VCP source emissions relative to those for transportation. However, compared to measurement data, model performance is not substantially improved by the adjustment of VOC emissions of current sources. In brief, augmented VOC emission inventories impact simulated concentrations of pollutants, but may not improve the performance of models used for the design of emission control policy without more refined representation of missing VCPs sources in the inventory.

In this short review, the green potential of solvents from biomass is analysed. A selection of the chemicals under study has been made, and the information brought together has been examined according to different types of properties. To explore the volatile organic compound character, the environmental fate and potential applications and several key physicochemical properties such as hydrophobicity, vapour pressure or solubility have been gathered and evaluated. Furthermore, the (eco)toxicological information of solvents from biomass has also been analysed. Information about the effect of these types of solvents in several organisms in the environment has been collected. Similarly, the toxicity of these chemicals has also been studied, and information has been analysed according to the type of endpoint studied.

Optical sensors (etalons) composed of poly(N-isopropylacrylamide) (pNIPAm)-based microgels have been developed for detecting volatile organic compound (VOC) vapors such as hexane, cyclohexane, chloroform, petroleum ether and tetrahydrofuran (THF). PNIPAm-based microgels were synthesizedandcharacterized, and etalons were subsequently fabricated, which exhibited visual color and multipeak reflectance spectra. The color change of etalons in response to VOC vapor exposure was evaluated by bubbling the vapors through water containing the etalon, and the shift in the reflectance peak position monitored. The results showed that the etalons were able to respond to the VOC vapor by changing their color, as evidenced by a shift in the position of the reflectance peak. Dynamic light scattering data showed that the microgels dissolved in solutions composed of the respective VOCs exhibit sizes that vary with VOC type and concentration, which leads to the optical response observed for the microgel-based etalons. The results showed that the etalons were most responsive to THF, which we conclude is a result of cononsolvency of the microgels in THF/water mixtures. With the setup used here, we could detect 1.27 mM THF vapor in 4 min, although the limit of detection, and detection time, can be tuned by changing the experimental conditions. Finally, we showed that individual etalons can be used at least 3 times to detect THF vapor without a loss in etalon function, which suggests that the etalons can be used multiple times for detecting VOC vapors.

Hexanal is a specific volatile organic compound (VOC) for monitoring the quality of various agricultural products and a biomarker for diagnosing lung cancer of human beings. However there is no existing hexanal gas sensor with high sensitivity and selectivity for hexanal detection in the presence of water vapor. Addressing this challenge, a quartz crystal microbalance (QCM) gas sensor modified with a hydrophobic molecularly imprinted polymers (MIPs) composite for hexanal detection was reported. Hexanal could selectively bind with the MIPs through hydrogen bonding while the hydrophobic silica nanoparticles could give the electrode resistant to water vapor. The QCM gas sensor showed the highest response to hexanal among the other tested vapors, and had little responses towards TMA, NH3, ethanol, acetone, acetic acid and diethyl ether. Octanal reached the second place followed by nonanal, but they two caused much less frequency shifts than that of hexanal. The QCM gas sensor was reliable for hexanal detection in the range of 1–80 ppm and able to detect hexanal amount from about 14.1 ppm–27.3 ppm in grass carp fillets with about 80% relative humidity in 7 days. The results displayed positive correlation with the solid phase micro extraction-gas chromatography mass spectrometer (SPME-GCMS) analysis of the same grass carp fillets samples, and the correlation coefficient was 0.98. It may offer some new ideas for gas sensors development with high sensitivity and selectivity in areas of quality evaluation of agricultural products and health evaluation of human beings.

Ambient volatile organic compounds (VOCs) measured hourly by the photochemical assessment monitoring station (PAMS) in Taichung were collected to analyze characteristics and provide source apportionment of VOCs. In this study, aromatics and alkanes were found to be the major VOC categories. The major species included toluene, m,p-xylene, propane, ethane, n-butane, and isopentane, which came from the east and southeast. VOC concentrations were highest in March and lowest in July, due to temperature, accumulated precipitation, boundary layer effects, and photochemical reactions. Positive matrix factorization analysis showed that industrial emissions (solvent usage and industry) were the major source, which originated from the northwest to south. Traffic emissions (fuel evaporation and vehicular emissions) were the second highest source and came from the southeast. An estimation of ozone formation suggests that industrial emissions were still a key source. Therefore, effective abatement strategies for industrial emissions should be given priority for VOC control.

As a hazardous volatile organic compound (VOC), formaldehyde (FA) is found ubiquitously in both polluted and unpolluted environments. Hence, for the proper control of FA, techniques for rapid and precise quantitation of FA are in great demand. However, because of its low molecular weight and high reactivity, its quantitation generally requires complicated procedures (such as combination of sampling through 2,4-dinitrophenylhydrazine (DNPH) derivatization and detection through high-performance liquid chromatograph (HPLC)). Such an approach, despite proven reliability, is inefficient for fast tracking of FA level under dynamic conditions. To overcome such limitations and to facilitate the near real-time monitoring of gaseous FA, we developed an alternative detection method based on a gas chromatograph/barrier discharge ionization detector interfaced with a large-volume injection system (LVI/GC/BID). The reliability of lab-made gaseous standards of formaldehyde was investigated based on thermal cracking of paraformaldehyde. The developed LVI/GC/BID approach allowed the detection of gaseous FA with a method detection limit (MDL) of about 0.13 ng (0.21 ppm for 0.5 mL sample) over the linear dynamic range of 0.29–5300 ng with relative standard deviation (RSD) of 1.19% compared with the direct injection-based GC/BID MDL of 2.41 ng (6.56 ppm for 0.3 mL sample) and RSD of 3.35%.

Moisture-dominated cure adhesives (e.g., silicone sealant) are an important source of volatile organic compound (VOC) emissions indoors, particularly in newly decorated buildings. Understanding their emission behavior could aid in selecting better control strategies for acceptable indoor air quality. In this study, a one-dimensional emission model that can predict the entire VOC emission process from moisture-dominated cure adhesives was established. The model has distinct physical or chemical parameters; thus, the model can be readily scaled up and the effects of environmental factors, such as temperature and humidity, can be evaluated. The emission of a type of neutral silicone sealant was measured using an environmental chamber and the main emission VOC (2-butanone oxime, MEKO) was used to validate the model. The model parameters of neutral silicone were measured or estimated to predict the concentration in the chamber. The experimental data and model predictions agreed well. The study indicates that MEKO emission is strongly coupled with the curing process. The factors that can influence the cure reaction are also the main influencing factors on the MEKO emission process.

The United States (US) Environmental Protection Agency (EPA)'s SPECIATE database contains speciated particulate matter (PM) and volatile organic compound (VOC) emissions profiles. Emissions profiles from anthropogenic combustion, industry, wildfires, and agricultural sources among others are key inputs for creating chemically-resolved emissions inventories for air quality modeling. While the database and its use for air quality modeling are routinely updated and evaluated, this work sets out to systematically prioritize future improvements and communicate speciation data needs to the research community. We first identify the most prominent profiles (PM and VOC) used in the EPA's 2014 emissions modeling platform based on PM mass and VOC mass and reactivity. It is important to note that the on-road profiles were excluded from this analysis since speciation for these profiles is computed internally in the MOVES model. We then investigate these profiles further for quality and to determine whether they were being appropriately matched to source types while also considering regional variability of speciated pollutants. We then applied a quantitative needs assessment ranking system which rates the profile based on age, appropriateness (i.e. is the profile being used appropriately), prevalence in the EPA modeling platform and the quality of the reference. Our analysis shows that the highest ranked profiles (e.g. profile assignments with the highest priority for updates) include PM2.5 profiles for fires (prescribed, agricultural and wild) and VOC profiles for crude oil storage tanks and residential wood combustion of pine wood. Top ranked profiles may indicate either that there are problems with the currently available source testing or that current mappings of profiles to source categories within EPA's modeling platform need improvement. Through this process, we have identified 29 emissions source categories that would benefit from updated mapping. Many of these mapping mismatches are due to lack of emissions testing for appropriate source categories. In addition, we conclude that new source emissions testing would be especially beneficial for residential wood combustion, nonroad gasoline exhaust and nonroad diesel equipment.

The European Solvents Industry Group (ESIG) has established volatile organic compound emission inventories for solvents for individual countries or groups of countries within the European Union for 2008, 2009, 2013 and 2015. A top-down approach has been adopted starting with EU-wide solvents industry sales data as supplied by solvent manufacturers, to which atmospheric release factors were applied for each solvent use sector. ESIG total solvent emissions for the EU ranged from 2159 thousand tonnes year−1 in 2008 to 1981 thousand tonnes year−1 in 2015. Comparison with internationally-agreed solvent emissions suggests that official estimates of total solvent emissions across the EU are over 30% too high by comparison with ESIG estimates and showed too high a trend with time. Using official statistics on chemical exports and imports for each country, ESIG has been able to compile solvent emissions for each European country or groups of countries. The over-estimation by the internationally-agreed solvent emissions compared with the ESIG estimates for Europe as a whole was mirrored in the individual country estimates for 2008, 2009, 2013 and 2015. No simple, uniform relationship between national solvent emissions and per capita population for either total or domestic sector solvent emissions was found. Assumption of uniform solvents emission factors on a per-head of population basis, has led to the introduction of inaccuracies in internationally-agreed solvent emission inventories. More detailed work with Member States has shown that non-solvents are also being included in the official solvent VOC inventories-indeed these VOC inventories are for ‘solvents and other product use’.

Conventional volatile organic compound (VOC) monitoring based on thermal desorption - gas chromatography–mass spectrometry (TD-GC–MS) or gas chromatography-flame ionization detector (TD-GC-FID) is relatively cumbersome and expensive. In this study commercial off the shelf low-cost and low-power photo-ionization detector (PID) sensors are used as simple detectors in VOC analysis systems based on GC, including a miniaturised GC × GC device with portable, low-cost, and low-energy-consumption features. PID sensors produce a voltage signal positively proportional to VOC concentration, which when incorporated into a TD-GC system gave limit of detection of 0.02 ppbV for isoprene. To test PID performance in real-world applications, PID sensors were deployed as (i) a second alternative detector in a GC-Quadruple Time Of Flight Mass spectrometry (GC-Q-TOF-MS), and (ii) the main detector in a compact two-dimensional gas chromatograph (GC × GC). PID sensors with 10.6 eV and 11.7 eV lamps were used to measure eight toxic chemicals including organic sulfide and organic phosphonates via GC; two species were ionized by a 10.6 eV lamp and four species by the 11.7 eV lamp. Commercially available low-cost PIDs designed for standalone could be straightforwardly and effectively re-used as detectors in compact GC × GC systems, in this work showing excellent VOC sensitivity, fast response and low operational demands compared to comparable field instruments based on GC-FID or MS.

The separation and detection of human breath play a significant role in early and non-invasive disease diagnosis. Various volatile organic compound (VOC) gases are considered as the biomarkers of a nonalcoholic fatty liver disease (NAFLD) patient. In this paper, a micro gas chromatography (GC) column used for VOCs separation of the NAFLD breath sample was presented, from its design, fabrication and separation performance testing. The serpentine column made using microelectromechanical system (MEMS) technology was chosen for its relatively small band broadening. The micro pillar configuration was simulated and optimized. The 3 m and 1 m long column with a cross-section of 200 μm × 240 μm was fabricated by deep-reactive-ion-etching (DRIE) method and sealed with anodic bonding. The stationary phase was coated to the inner wall of the column by static coating. The column was installed into the conventional gas chromatography to test separation performance of the GC. The nonpolar alkane mixture containing the NAFLD biomarker gas pentane was separated and the experimental factors such as the temperature and the carrier gas flow rate were studied. The results indicated that the micro GC column can effectively separate alkanes from C5-C12 within 5 min. This could help the micro detector of micro GC system to quickly identify the contents or concentrations of characteristic alkanes. The micro GC column can meet the requirements of the micro GC system for the breath analysis of the NAFLD or other metabolic liver diseases. The micro column assembled with micro gas detector and preconcentrator can be hopefully developed into a portable breath analysis device.

In this study, the Potential theory-based Manes method was used to describe competitive multicomponent adsorption of VOC and water vapor onto activated carbon. The thermodynamically consistent method was extended to water-miscible VOCs using a Raoult’s law-like relation. The method uses as input the pure single-component adsorption isotherms, which were obtained from the modified Dubinin-Radushkevich (MDR) model for VOCs and the Qi-Hay-Rood (QHR) model for water vapor. The MDR model was applicable for the studied VOCs (2-propanol, acetone, n-butanol, toluene, 1,2,4-trimethylbenzene) with an overall r2 value of 0.998. The QHR isotherm provided a good description for water vapor adsorption on activated carbon with 0.999 r2 value. Experimental validation tests revealed that the multicomponent adsorption isotherm model predicted the VOC adsorption capacity during competitive adsorption with water vapor with an overall mean relative absolute error (MRAE) of 1.9% for non-polar VOCs and 5.2% for polar VOCs. These results are encouraging, as they indicate a good agreement between modeled and experimental results. Hence, the model can potentially be integrated with dynamic adsorption models to optimize adsorber design and operation or model adsorption kinetics.

Isoprene, the highly reactive volatile organic compound, is used as monomer for the synthesis of several useful polymers. Its extensive production and usage leads to contamination of air. Once released, it alters the atmospheric chemistry by reacting with hydroxyl radicals (OH) and nitrogen oxides (NOx) to generate tropospheric ozone. Its prolonged exposure causes deleterious effects in human and plants. Therefore, its removal from the contaminated environment through biodegradation, provides a promising remedial solution. In the present study, isoprene utilizing bacteria namely, Pseudomonas sp., Arthrobacter sp., Bacillus sp. Sphingobacterium sp., Sphingobium sp., and Pantoea sp. were isolated and characterized from leaf surface of Madhuca latifolia and Tectona grandis, and also from soils under these plants. Their isoprene degrading capability and kinetics were assessed in batch mode. The isoprene degradation study indicated Pseudomonas sp. to be the most efficient isoprene degrader.

To assess the best sorbents available in real-world treatment of airborne volatile organic compounds (VOCs), we explored four sorbent performance metrics (10% breakthrough volume, space velocity, regeneration cycles, and cost) against benzene, a representative VOC, using well-known sorbents in the partial pressure (Pbenzene) range 0.01 – 1 Pa. Accordingly, some common materials (e.g., activated carbons) outperformed novel materials like MOFs. The performance of MOFs was often exaggerated as data were generally collected under unrealistic Pbenzene (e.g., >5,000 Pa). The use of metrics appropriate to real-world conditions is thus critical for selecting sorbents.

Xylene is a harmful and hazardous volatile organic compound (VOC) indoors, thus selective and sensitive detection for subppm-level xylene is crucial, however a remained challenge. In this work, p-NiO/p-NiCr2O4 nanocomposites were successfully synthesized through a simple hydrothermal route and used as sensing materials. In the comparative gas sensing test, the sensor fabricated from NiO/NiCr2O4 (Cr/Ni = 25 at%) nanocomposite exhibited the highest response (66.2–100 ppm) to xylene, which was 37.2 times higher than that of the pure NiO sensor. Moreover, the NiO/NiCr2O4 nanocomposite gas sensor showed not only superior xylene selectivity with low cross-responses to interfering gases such as ethanol (Sxylene/Sethanol = 11.8) and acetone (Sxylene/Sacetone = 10.2) but also ppb-level detection limit (1.2–50 ppb xylene) at 225 °C. The synergistic catalytic effect between NiO and NiCr2O4, optimized structural parameters and marked resistive variation due to the formation of nanoscale p-p heterojunctions were regarded as the main reasons for the ultrasensitive and selective xylene detection.

Pd nanoparticles (NPs)-based catalysts were synthesized, characterized and used to catalyze the oxidation of volatile organic compound (VOC) pollutants. A biogenic method was employed to synthesize Pd NPs with tunable sizes by using Cacumen platycladi (CP) leaf extract as a reducing agent. The Pd NPs were then anchored over a support which was made from KIT-6-templated three-dimensionally ordered mesoporous (3DOM) CeO2 (i.e., kit-CeO2) to form xPd/kit-CeO2 catalysts with various Pd loadings (x denotes Pd loading, wt%). The physicochemical properties such as morphology, structure and elemental distribution of the xPd/kit-CeO2 catalysts and the support were comprehensively characterized. The BET surface areas of the support and catalysts varied in the range of 105–109 m2/g. In the benzene oxidation catalyzed by 0.5Pd/kit-CeO2, the temperature required for 90% benzene conversion was significantly reduced to 187 °C, compared with the published results. Furthermore, the 0.5Pd/kit-CeO2 showed stable catalytic activity after being used for 150 h in on-stream reaction. Besides, density functional theory calculation indicated that the synergetic effects of Pd NPs and the kit-CeO2 support would facilitate the activation of benzene adsorbed on Pd NPs prior to oxidation. The catalytic performance of 0.5Pd/kit-CeO2 correlated well with the features of CP leaf extract, high Pd0 concentration, abundant oxygen adspecies, low temperature reducibility, and strong interactions between Pd NPs and kit-CeO2 support. The biogenic method is better than the chemical method to synthesize Pd NPs with higher catalytic activity while the kit-CeO2 is better than the commercial CeO2 and KIT-6-templated transition metal oxides (e.g., Fe2O3 and Co3O4) as a supporting material.

Representative indoor volatile organic compounds (VOCs) such as benzene, xylene, toluene, formaldehyde, and ethanol need to be detected in a highly sensitive and discriminative manner because of their different impact on human health. In this study, pure and 0.05, 0.1, 0.3, and 0.5 at% Fe-doped In2O3 nanofibers were prepared by electrospinning and their gas sensing characteristics toward the aforementioned VOCs were investigated. The doping of In2O3 nanofiber sensor with 0.05 and 0.1 at% Fe shifted the temperature to show the maximum responses to benzene, xylene, and toluene, and reduced responses to ethanol and formaldehyde, thus demonstrating changed gas selectivity. The gas sensing characteristics of 0.5 at% Fe-doped In2O3 nanofiber sensor were substantially different from those of the other sensors. Significantly different gas sensing patterns of pure and Fe-doped In2O3 sensors could be used to discriminate between the five different VOCs at 375 °C and to distinguish between the aromatic and non-aromatic gases at all sensing temperatures. The mechanism underlying the Fe-induced change in gas sensing characteristics has been discussed in relation to the variation of catalytic activity, morphology, oxygen adsorption, and charge carrier concentration.

Volatile organic compounds (VOCs) emitted from the human body are an important source of bioeffluents to indoor environments. A mid-sized (2 m × 2 m × 2 m), air-tight environmental chamber was used to measure VOC emissions from the whole body of each participant. Air tightness, homogeneity, adsorption, and desorption were controlled to satisfy the requirements of the experiment. Background concentrations of VOCs and ozone were maintained at a low level. To estimate human emission rates, the VOC concentrations of the chamber's air and of exhaled breath were collected by Tenax-TA tubes and analyzed through gas chromatography-mass spectrometry. Fourteen healthy participants enrolled in the pilot experiment. The chemical components of volatile emissions from the breath and the whole body of participants were found to be similar. The average emission rate of total VOC (TVOC) from the whole-body was 742.8 μg/h (SD = 464.7 μg/h), while the average TVOC emission rate from the breath samples was 41.4 μg/h (SD = 11.7 μg/h). In addition, the VOCs detected in the whole-body analyses were mainly alkanes with 3–6 carbons, while the VOCs detected in the breath sample analyses were primarily acetone and isoprene. In comparison with previous studies, the detected VOC types were mostly consistent, but the specific compounds varied. Moreover, the emission rates of very volatile organic compounds (VVOCs) were lower in this study, whereas the aromatics were on the same order of magnitude.

Although many properties of plantation wood are greatly enhanced by heat treatment, large quantities of volatile organic compounds (VOCs) are released from this process, resulting in potential problems for the environment and human health. Volatile byproducts were collected from Populus tomentosa wood that was treated at 160, 180, 200, and 220 °C for 2 h. The VOC gases were partly collected at the heating, holding, and cooling stages of the process and were then analyzed by gas chromatography-mass spectrometry and thermogravimetry. The results show that over 90% of the volatiles from the first and third stages were alkane compounds. The mass losses in the heating and holding stages were almost at the same level, and the liquid byproduct contained approximately 48% phenolic products at 160 °C. The volatiles at 180 °C were mainly alkanes, terpenes, and aromatic compounds, and the absolute amount of VOCs released in the holding stage was much higher than that in the heating stage. The concentrations of phenols and ketones in the liquid byproducts decreased when the treatment temperature was increased, and more complex chemicals such as N-containing compounds emerged. Ester and aromatic compounds increased with the treatment temperature. The condensate collected at 160 °C exhibited considerable biological activity in the bacterial and mildew resistance tests. These results suggest that thermally treated byproducts can be turned into wood preservatives, which would also make the wood heat treatment cleaner.

Quantitative analysis of volatile organic compounds (VOCs) using spectroscopy technology has invariably been a formidable problem. In this paper, chemoselective response dyes were employed as probes to capture VOCs, including a novel chemoselective response dye called BODIPY. The spectral data of distinct sensor color difference pattern due to the rapid chemical reaction between the dye molecule and organic compound molecule was collected by portable Visible-Near Infrared Spectroscopy (Vis-NIRS) equipment. Afterward, the synergy interval partial least squares (Si-PLS) algorithm was used to process spectral data and establish predictive models for pure VOCs in the mixture and actual samples with the high correlation coefficient of determination of the prediction set (Rp) value and the low root mean square error of prediction (RMSEP) value. This new method formed by a color-sensitive sensor made of chemoselective dye combined with Vis-NIRS technology not only achieves quantitative detection of VOCs but also address the limitations of spectrum technology in this field. Finally, we obtained the expected results, the average prediction rate of the concentration of the six pure VOCs counted as 107 ± 20%, the average prediction rate of pure VOCs in the mixture counted as 101 ± 12%. Meanwhile, the average prediction rate of VOCs in the actual samples counted as 108 ± 31%, when this new method was applied to the detection of VOCs.

This study explored a click method of using filter paper (FP) and a polydimethylsiloxane (PDMS) polymer coating solution to prepare a cost-effective volatile organic compound (VOC) preconcentrating sampler. This is the first report of successfully cross-linking a hydrophobic polymer with cellulose in filter paper via a sol-gel method and its application to the preconcentration of headspace VOCs. Our Fourier transform infrared spectroscopy analysis results of the PDMS-coated filter paper (FP-PDMS) showed that the spectral intensity of the alcoholic O H stretch from FP or PDMS was reduced by the addition of trifluoroacetic acid to the PDMS solution, which indicated that an alcohol group in PDMS underwent cross-linking with another alcohol group in the cellulose or PDMS. Scanning electron microscopy (SEM) images of FP-PDMS revealed that the fibrous structure of the FP surface was partially compromised by the PDMS coating, but the porous structure of FP is partially preserved. The addition of the PDMS coating to the FP increased the efficiency of the preconcentration of headspace VOCs evaporated from water. Three types of carbon additives, activated carbon, graphite, and fullerene, were tested in order to evaluate their effects on headspace VOC preconcentration efficiency for FP-PDMS, with the addition of activated carbon found to provide the largest increase in preconcentration efficiency. The extent of the enhancement of the preconcentration efficiency provided by the carbon additives varied with the VOC compounds, as well the type of carbon additive. The FP-PDMS both with and without activated carbon can be used to successfully preconcentrate benzene, toluene, ethylbenzene, and m-xylene from sub-ppb water samples with the headspace gas sampling method.

Coke production is a significant source of ambient volatile organic compound emissions; thus, stringent control measures must be applied. We fully characterized the trends in volatile organic compound emissions by the coking industry in China between 1949 and 2016 based on a factory-based database and process-specific emission factors. We then projected the reduction potentials in these emissions if different control policies were implemented in 2020 based on three emission scenarios. The results indicate that: (1) the emission factor of volatile organic compounds for coke plants under uncontrolled conditions was 3.065 g/kg coke, and benzene, toluene, and acetone were the most abundant emission species. (2) The annual volatile organic compound emissions from the coking industry increased by an order of magnitude from 3.38 Gg in 1949 to 1376.54 Gg in 2016. The emissions show distinct spatial characteristics, with significantly higher emissions in northern China than in other areas. (3) Compared to the uncontrolled scenario, if basic or more stringent control measures were fully implemented in China in 2020, then volatile organic compound emissions would be reduced by 59% or 82%, respectively. (4) Controlling coke oven flue gases through efficient combustion, sealing and cleaning the openings of coke ovens, and using gas blanketing or carbon absorbers in by-product facilities were the most effective technologies for controlling volatile organic compound emissions from coke production.

An improved gas recovery system (GRS) using activated-carbon fiber-cloth (ACFC), electrothermal swing adsorption (ESA), and carrier gas recirculation was shown to capture and recover >99% isobutane while reducing N2, H2O, and energy consumption. ACFC-15 was selected as the adsorbent after a trade-off of adsorption capacity and cost. Carrier gas recirculation was used for the first time to conserve N2 and H2O at relative humidity (RH) up to 80% while recovering volatile organic compound (VOC) (i.e., isobutane). When RH is 24% and 77%, overall energy (EOverall) consumed with recirculation decreases by 2.5% and 26% compared to without recirculation, respectively. Recommendations are provided to reduce the gap of energy consumption of the GRS with recirculation based on idealized and experimental conditions. Unique contributions and importance of this work are demonstrating that carrier gas recovery and reuse can be used to better conserve N2, H2O, and energy; analyzing specific energy consumption values; and proposing improvements of such a system to let the GRS with recirculation operate closer to idealized conditions.

Previous investigations on pizza dough lactic acid bacteria (LAB) revealed that facultative heterofermentative species (FHS) were more represented than obligate heterofermentative species (OHS) within the Lactobacillus genus. Thus, the main hypothesis of this work was that facultative and obligate heterofermentative Lactobacillus species can impact differently the appreciation of baked pizza. The performances of different Lactobacillus, including L. sanfranciscensis, L. brevis and L. rossiae among OHS and L. plantarum, L. graminis and L. curvatus among FHS were tested in single or multiple combinations during pizza production. The values of pH, total titratable acidity and LAB levels indicated that the acidification process was almost comparable among trials. The fermentation quotient of FHS trials was above 4.0. All trials were dominated by the added LAB and for the trials with the multiple strain starter inoculums, the species found at the highest cell densities were L. sanfranciscensis, L. brevis and L. plantarum. Significant differences among pizzas were found for weight loss, colour, morphology and volatile organic compounds (VOCs). The last analysis revealed the presence of eight chemical classes with aldehydes, esters, alcohols and acids as major compounds and allowed the separation of the trials FHS and OHS. Sensory attributes were significantly different for judges and pizzas and the most relevant differences were found for crust colour, presence of bubbles, resistance to tearing, crispness and chewiness. The overall assessment reached the highest scores for the mixed culture of OHS and FHS together.

If volatile organic compound (VOC)-contaminated soil exists underneath a building, vapors may migrate upwards and intrude into the interior air of the building. Most previous models used to simulate vapor intrusion (VI) were developed by assuming that the source was constant, although a few recent models, such as the Risk-Based Corrective Action (RBCA) Tool Kit (TK) model, have been developed to consider source depletion (SD). However, the RBCA TK model ignores the effects of building characteristics due to its assumption that the ground is not covered by the actual building it models, which leads to incorrect results since the presence of the building affects the SD. In this study, a SD model is developed based on the three processes of VI while considering the impact of key building parameters on SD. The proposed model (i.e., the SD model) still follows the law of mass conservation, and the sensitivity analysis shows that the soil-building pressure differential (dP) is an important building characteristic that affects SD. Taking trichloroethylene (TCE) for simulation in the case of a soil concentration below the saturation concentration, as the soil permeability decreases, the differences in the results between the SD model and RBCA TK model decrease; as the Peclet number decreases, the effect of the dP on the results of the SD model decreases. The new model only accounts for the migration of contaminants at the source of depletion; therefore, the model is more applicable for these contaminants, which are considered to have low-biodegradable characteristics. Furthermore, since the model emphasizes the impact of buildings on the source, it is applicable when there is a considerable building area above the source, such as large commercial buildings or residential communities with underground parking lots, which exist in most cities.

Ultraviolet photocatalytic oxidation process (UV-PCO) is a promising approach for removing indoor volatile organic compound (VOC). Although the adequate efficiency of PCO in laboratory conditions has been proven, the application of PCO in VOCs degradation has been greatly hindered in large-scale applications. The effect of scaling up and real conditions cause some limitations for large-scale systems. Based on our knowledge, despite extensive published research on PCO of TiO2-based photocatalysts in bench-scale setups, there is a lack of studies regarding the effects of scaling up and by-product generation in pilot and full-scale setups. The main objective of this study is to investigate the scaling effect on toluene and isobutanol removal efficiency and by-product generation in conditions close to the real application. For this purpose, three test setups i.e., full, pilot, and bench-scale, were employed to investigate the PCO removal of VOC pollutants in the gas phase. Also, the effect of light type on the performance of PCO was examined in the pilot and full-scale. A brief description of three setups is presented, followed by experimental results and discussions about the difference between each setup. The PCO efficiency and by-product generation rate are evaluated in conditions close to the real application, considering low-level contaminant concentration, small residence time, and high flow rate. The relative humidity for all experiments is kept in the comfort zone (RH ∼50 ± 5%). The performance of vacuum UV (VUV) photolysis and VUV-PCO in pilot and full-scales, and UVC-PCO in all three scales, are compared and discussed.

The legal commercialization of Cannabis for recreational and medical use in certain US states has effectively created a new and nearly unregulated cultivation industry. Within the city limits of Denver, Colorado, there are now more than 600 registered Cannabis spp. cultivation facilities (CCFs) for recreational and medical uses, each containing thousands of plants. Ambient measurements collected inside growing operations pre-legalization have found concentrations as high as 50–100 ppbv of terpenes; a group of highly reactive biogenic volatile organic compounds (BVOCs) and known precursors for the formation of ozone and particulate matter (PM). Due to its illicit nature there has been insufficient experimental data produced to determine Cannabis spp. emission rates. This study used, for the first time, an enclosure chamber and live Cannabis spp. plants during a 90-day growing period consisting of four different strains of Cannabis spp.: Critical Mass, Lemon Wheel, Elephant Purple, and Rockstar Kush. These measurements enabled characterization of terpenes and estimates of emission capacity (EC, μgC g−1 hr−1) at standard conditions. During peak growth, the percentages of individual BVOC emissions were dominated by β-myrcene (18–60%), eucalyptol (17–38%), and d-limonene (3–10%) for all strains. Our results showed large variability in the rate and composition of terpene emissions across different strains. For the Critical Mass and Lemon Wheel, the dominant terpenoid was eucalyptol (32% and 38%), and it was β-myrcene (60% and 45%) for the Elephant Purple and Rockstar Kush. Critical Mass produced the highest terpene emission capacity (8.7 μgC g−1 hr−1) and Rockstar Kush the lowest (4.9 μgC g−1 hr−1). With 600 CCFs in Denver, and assuming 10,000 plants per CCF, an emission capacity of 8.7 μgC g−1 hr−1 would more than double the existing rate of BVOC emissions to 520 metric ton year−1. Using Maximum Incremental Reactivity (MIR) values the total ozone formation potential from all these emitted species could produce 2100 metric tons year−1 of ozone, and based on published secondary organic aerosols yields 131 metric tons year−1 of PM. It is likely that the ECs calculated here are lower than those achieved in CCFs where growing conditions are optimized for rapid growth and higher biomass yields. Further studies including a greater number of the 620 available Cannabis spp. strains and a wider range of treatments are needed to generate a representative dataset. Such a dataset could then better enable assessments of the potential impacts of this new industry on indoor and regional air quality.

1,2-dichloroethane (1,2-DCE) is a representative industrial chlorinated volatile organic compound (CVOC) making great hazardous to the environment and human health. In this work, LaSrMnCoO6 (LSMC) double perovskite-type materials with high thermal stability and coke resistance in 1,2-DCE oxidation were prepared by a facile sol-gel method. Based on this, a series of CrOx/LaSrMnCoO6 catalysts (Cr/LSMC, CrOx loading = 5 to 20 wt.%) which combine the merits of CrOx (high activity and chlorine tolerance) and LaSrMnCoO6 were synthesized and adopted in deep oxidation of 1,2-DCE for the first time. As expected, obvious synergistic effects between CrOx and LSMC on 1,2-DCE destruction were observed. Amongst, 10 wt.% CrOx/LaSrMnCoO6 (10Cr/LSMC) shows the best catalytic activity with 90% of 1,2-DCE destructed at 400 °C. Furthermore, the outstanding catalytic durability and water resistance of 10Cr/LSMC in 1,2-DCE oxidation were also demonstrated. In addition to this, the reaction pathway of 1,2-DCE decomposition over Cr/LSMC materials was discussed based on the results of online product analysis. We found that the enhanced catalytic performance of Cr/LSMC materials can be reasonably attributed to their high reducibility, excellent 1,2-DCE adsorption capability, and large amounts of surface active lattice oxygen species. It can be anticipated that the Cr/LSMC catalysts are promising materials for CVOC elimination and the results from this work could also provide some new insights into the design of catalysts for CVOC efficient destruction.

Vehicle emissions have become the major source of air pollution as well as heavy metals pollution accompanied with unprecedented economic development and urbanization in China. Yunnan province, the congruity area of undeveloped region with high vehicle population increasing, as well as special natural conditions, was taken as the study area. We estimated the vehicle emissions during 2003–2015 with COPERT IV model, including private cars (PC), buses (BUS), light duty vehicles (LDV) and heavy duty trucks (HDT), then analyzed the vehicle emission characteristics, involving CO, CO2, SO2, NOx, NO, NO2, N2O, NH3, Volatile organic compounds (VOC), Ambient Air Non-Methane Volatile Organic compound (NMVOC), CH4, PM2.5, PM10, PM (exhaust), Cadmium and Zinc. The results indicated that all pollutants as well as heavy metals were increased at different growth trends except SO2 although more stringent emission standard implementation, the rising of vehicle population become the main contributor to the vehicle emission growth, and CO2 emission was the major vehicle emissions accounted for one third of total CO2 emissions in Yunnan. PC was the main contributor to the rising of CO, VOC, NMVOC, CH4, NH3, CO2, Cadmium and Zinc, which was also the major vehicle growth type; HDT and LDV brought to the emissions of N2O, NOx, NO, PM10, NO2, PM2.5, and PM (exhaust) respectively. At last, uncertainty of emission estimation was analyzed based on the Monte Carlo simulation. The vehicle emission become one critical field of emission reduction in Yunnan which should be given greater emphasis to environmental concerns.

International audience; Nowadays, monitoring of volatile organic compounds (VOCs) is very important in various domains. In this work, we aimed to develop sensitive olfactory biosensors using odorant binding proteins (OBPs) as sensing materials. Three rat OBP3 derivatives with customized binding properties were designed and immobilized on the same chip for the detection of VOCs in solution by surface plasmon resonance imaging (SPRi). We demonstrated that the proteins kept their binding properties after the immobilization under optimized conditions. The obtained olfactory biosensors exhibited very low limits of detection in both concentration (200pM of beta-ionone) and in molecular weight of VOCs (100g/mol for hexanal). Such a performance obtained with SPRi in solution is especially remarkable. We hypothesized that the binding of VOCs to the active sites of OBPs induced a local conformational change in the proteins. This change would give rise to a variation of refractive index, to which SPRi is extremely sensitive. In addition, the olfactory biosensors showed a high selectivity especially at relatively low VOC concentrations. With optimized regeneration procedures, they also showed very good repeatability not only from measurement to measurement but also from chip to chip with a lifespan up to almost two months. These olfactory biosensors are particularly interesting for trace detection of VOCs in solution.