Mixture Of Volatile Organic Compounds Research Articles

Biennial Variation and Herbivory Affect Essential Oils of Ipomoea murucoides and Stomata Density of Neighbor Plants

Essential oils (EOs) are mixtures of volatile organic compounds that mediate plant interactions and are also appreciated for their biological properties in aromatic plants. However, the study of EOs in wild plants with biological activity has been neglected. Ipomoea murucoides is a wild species with allelopathic and insecticide activities; however, the climate factors associated with EOs and their role in intra- and interspecific interactions are still unknown. We investigated the effects of temperature, rain, and solar irradiance for two years on the EOs of I. murucoides and documented the effect of herbivory (without, <20%, >20%, and mechanical damage) on their composition. We evaluated the receptivity to possible infochemicals in conspecific and congeneric neighbors to I. murucoides plants exposed to methyl jasmonate (MeJA), herbivory by Ogdoecosta biannularis and without an elicitor. We measured the stomatal density and aperture in the second leaf generation of the neighbor plants. The year and herbivory >20% affected the composition of EOs. Nerolidol could be a biological marker for herbivory. We concluded that herbivory and rain irregularity contribute to EOs changing. The response in the stomatal density in plants not consumed by I. pauciflora but near I. murucoides under MeJA or herbivory gives evidence of interspecific plant–plant communication.

Custom GC×GC configuration for the selective isolation or removal of compounds from complex samples

We developed a novel approach to selectively isolate or remove nearly any compound from complex mixtures of volatile organic compounds. This was achieved by customizing a GC×GC system with a Deans switch, a passive splitter, and a custom-made adapter for sample recollection. The new setup was evaluated with 106 standard chemicals covering a wide range of volatility (boiling points: 56 – 343 ⁰C) and polarity (log P: 0.2 – 9.4). The method was used to remove two notorious malodorous compounds from spoiled wine samples. We found that the recovery can be maximized if a custom-made adapter is attached directly on the flame ionization detector port (average recovery rate of 76 ± 7 % for the standards). Eventually, we could selectively isolate or remove chemicals with peaks separated by a minimum distance of 50 ms for the second column throughout the whole chromatographic run. The developed system is expected to mainly be used in the field of flavor and fragrance analysis (i.e., selection of flavors and odorants of interest or removal of off-flavor or malodorous compounds). At present, we can reasonably collect about 100 ng of each single compound and are currently working on sample enrichment to improve our method to isolate sufficient amounts for further chemical analysis (e.g. high sensitivity nuclear magnetic resonance or chemical ionization tandem mass spectrometry).

A Critical Review of Deep Oxidation of Gaseous Volatile Organic Compounds via Aqueous Advanced Oxidation Processes.

Volatile organic compounds (VOCs) are considered to be the most recalcitrant gaseous pollutants due to their high toxicity, diversity, complexity, and stability. Gas-solid catalytic oxidation methods have been intensively studied for VOC treatment while being greatly hampered by energy consumption, catalyst deactivation, and byproduct formation. Recently, aqueous advanced oxidation processes (AOPs) have attracted increasing interest for the deep oxidation of VOCs at room temperature, owing to the generation of abundant reactive oxygen species (ROS). However, current reviews mainly focus on VOC degradation performance and have not clarified the specific reaction process, degradation products, and paths of VOCs in different AOPs. This study systematically reviews recent advances in the application of aqueous AOPs for gaseous VOC removal. First, the VOC gas-liquid mass transfer and chemical oxidation processes are presented. Second, the latest research progress of VOC removal by various ROS is reviewed to study their degradation performances, pathways, and mechanisms. Finally, the current challenges and future strategies are discussed from the perspectives of synergistic oxidation of VOC mixtures, accurate oxidation, and resource utilization of target VOCs via aqueous AOPs. This perspective provides the latest information and research inspiration for the future industrial application of aqueous AOPs for VOC waste gas treatment.

Evaluation of urinary volatile organic compounds as a novel metabolomic biomarker to assess chronic kidney disease progression

BackgroundThere is a need to develop accurate and reliable non-invasive methods to evaluate chronic kidney disease (CKD) status and assess disease progression. Given it is recognized that dysregulation in metabolic pathways occur from early CKD, there is a basis in utilizing metabolomic biomarkers to monitor CKD progression. Volatile Organic Compounds (VOCs), a form of metabolomic biomarker, are gaseous products of metabolic processes in organisms which are typically released with greater abundance in disease conditions when there is dysregulation in metabolism. How urinary VOCs reflect the abnormal metabolic profile of patients with CKD status is unknown. Our study aimed to explore this.MethodsIndividuals aged 18–75 years undergoing kidney biopsy were included. Pre-biopsy urine samples were collected. All biopsy samples had an interstitial fibrosis and tubular atrophy (IFTA) grade scored by standardized assessment. Urine supernatant was extracted from residue and sampled for stir bar sorptive extraction followed by Gas chromatography–mass spectrometry (GC-MS) analysis. Post-processing of GC-MS data separated complex mixtures of VOCs based on their volatility and polarity. Mass-to-charge ratios and fragment patterns were measured for individual VOCs identification and quantification. Linear discriminant analysis (LDA) was performed to assess the ability of urinary VOCs in discriminating between IFTA 0 (‘no or minimal IFTA’ i.e. <10%, IFTA), IFTA 1 (‘mild IFTA’ i.e. 10–25% IFTA) and IFTA ≥ 2 (‘moderate or severe IFTA’ i.e. >25% IFTA). Linear regression analysis adjusting for age, sex, estimated glomerular filtration rate, diabetes mellitus (DM) status, and albuminuria was conducted to determine significantly regulated urinary VOCs amongst the groups.Results64 study participants (22 individuals IFTA 0, 15 individuals IFTA 1, 27 individuals IFTA ≥ 2) were included. There were 34 VOCs identified from GC-MS which were statistically associated with correct classification between the IFTA groups, and LDA demonstrated individuals with IFTA 0, IFTA 1 and IFTA ≥ 2 could be significantly separated by their urinary VOCs profile (p < 0.001). Multivariate linear regression analysis reported 4 VOCs significantly upregulated in the IFTA 1 compared to the IFTA 0 group, and 2 VOCs significantly upregulated in the IFTA ≥ 2 compared to the IFTA 1 group (p < 0.05). Significantly upregulated urinary VOCs belonged to one of four functional groups - aldehydes, ketones, hydrocarbons, or alcohols.ConclusionsWe report novel links between urinary VOCs and tubulointerstitial histopathology. Our findings suggest the application of urinary VOCs as a metabolomic biomarker may have a useful clinical role to non-invasively assess CKD status during disease progression.

Identification of Volatile Organic Compounds and Analysis of Aroma Characteristics in Ten Pear Syrups.

Aroma in food plays an important role in food perception and acceptance, which depends on various mixtures of volatile organic compounds (VOCs). Moreover, VOCs are of great significance for aroma identification. In this study, headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) technology was used to determine the VOCs in 10 pear syrups. A total of 127 VOCs were quantitatively determined, including 9 common VOCs and 46 characteristic VOCs of 10 pear syrups. The pear syrups were divided into three categories by cluster analysis, and thirty-eight differential VOCs were obtained using orthogonal partial least squares discrimination analysis (OPLS-DA) and fourteen key VOCs were selected by odor activity value (OAV). It was revealed that the key and common aroma components of pear syrups were butanoic acid, methyl ester, 2-methyl-, methyl ester and Hexanoic acid, and ethyl ester. The characteristic and differential VOCs were 10-Undecen-1-ol, Hexadecanal, n-Propylacetate, Cyclohexanol, 5-methyl-2-(1-methylethyl)-, (1S,2R,5S)-, Methional, Disulfide, dimethyl, 8-Nonenoic acid, ethyl ester, Naphthalene, 1,2-dihydro-1,1,6-trimethyl-, 3H-Purin-6-amine, N,N,3-trimethyl-, 2-Octanol,2,6-dimethyl-, Furyl hydroxymethyl ketone, Heptane, 2,2,4,6,6-pentamethyl-, and Butanoic acid,2-methyl-,methyl ester. The above results showed that different pear syrups had rich diversity in aroma compounds, with some components being shared among them while others are exclusive to specific syrups.

Volatile Organic Compounds Produced by Trichoderma asperellum with Antifungal Properties against Colletotrichum acutatum.

Managing plant diseases caused by phytopathogenic fungi, such as anthracnose caused by Colletotrichum species, is challenging. Different methods have been used to identify compounds with antibiotic properties. Trichoderma strains are a source of novel molecules with antifungal properties, including volatile organic compounds (VOCs), whose production is influenced by the nutrient content of the medium. In this study, we assessed the VOCs produced in dual confrontation systems performed in two culture media by Trichoderma strains (T. atroviride IMI206040, T. asperellum T1 and T3, and Trichoderma sp. T2) on Colletotrichum acutatum. We analysed the VOC profiles using gas chromatography coupled with mass spectrometry. The Luria Bertani (LB) medium stimulated the production of VOCs with antifungal properties in most systems. We identified 2-pentyl furan, dimethyl disulfide, and α-phellandrene and determined their antifungal activity in vitro. The equimolar mixture of those VOCs (250 µM ea.) resulted in 14% C. acutatum diametral growth inhibition. The infective ability and disease severity caused by the mycelia exposed to the VOCs mixture were notably diminished in strawberry leaves. Application of these VOCs as biofumigants may contribute to the management of anthracnose. LB represents a feasible strategy for identifying novel VOCs produced by Trichoderma strains with antifungal properties.

Fuel fumes and foliage: the fate of speciated gasoline VOCs during phytoremediation and their impact on the bacterial phenotype

The capacity of indoor plants including green walls to capture, deposit and remediate individual volatile organic compounds (VOCs) has been well documented. However, in realistic settings, plant systems are exposed to a complex mixture of VOCs from highly varied various emission sources. Gasoline vapour is one of the major sources of these emissions, containing high concentrations of the carcinogens benzene, toluene, ethylbenzene and xylene (BTEX). Using both solid phase micro extraction (SPME) and quick, easy, cheap, effective, rugged and safe (QuEChERS) sampling techniques, we assessed the dynamics of individual speciated gasoline VOC phytoremediation from the air and uptake within green wall plant species and growth substrates within a small passive green wall system, along with quantifying the phenotypic changes within the plant-associated bacterial communities resulting from gasoline exposure. Over 8 hours the green wall system achieved 100% removal of atmospheric benzene, 1,2,3-trimethyl, eicosane and hexadecane, benzene 1,3-diethyl-; 1,3,5 cycloheptatriene,7- ethyl and carbonic acid eicosyl vinyl ester. All plant species tested demonstrated the accumulation 45 petrochemical VOCs (pVOCs) with Spathiphyllum wallisii successfully accumulating the majority of pVOC functional groups after 24 h of gasoline exposure. Within the plants phyllospheric bacterial communities, changes in both cellular complexity and granularity appeared to increase as a result of gasoline exposure, while cell size diminished. This work provides novel findings on the VOC removal processes of botanical systems for realistic and highly toxic VOC profiles.

Pinewood VOC emissions protect from oxazolone-induced inflammation and dysbiosis in a mouse model of atopic dermatitis

Pinewood, increasingly used in construction and interior fittings, emits high amounts of volatile organic compounds (VOCs), which tend to accumulate in indoor air. Whether indoor VOCs affect the development of atopic dermatitis (AD) is a matter of debate. We aimed to evaluate the effects of pinewood VOCs on the development of AD-like inflammatory phenotype and linked microbiome alterations, both hallmarks of AD. An oxazolone-induced mouse model of AD was exposed to three different VOC concentrations emitted by pinewood plates throughout the experiment. The disease course and associated immunological and microbiological changes were evaluated. To validate and translate our results to humans, human keratinocytes were exposed to a synthetic pinewood VOCs mixture in an AD environment. Pinewood emitted mainly terpenes, which at a total concentration of 5 mg/m3 significantly improved oxazolone-induced key AD parameters, such as serum total IgE, transepidermal water loss, barrier gene alteration, inflammation, and dysbiosis. Notably, exposure to pinewood VOCs restored the loss of microbial richness and inhibit Staphylococci expansion characteristic of the oxazolone-induced mouse AD model. Most beneficial effects of pinewood VOCs were dose-dependent. In fact, lower (<3 mg/m3) or higher (>10 mg/m3) pinewood VOC levels maintained only limited beneficial effects, such as preserving the microbiome richness or impeding Staphylococci expansion, respectively. In the human in-vitro model, exposure of keratinocytes grown in an AD environment to a pinewood VOCs mixture reduced the release of inflammatory markers. In conclusion, our results indicate that airborne phytochemicals emitted from pinewood have beneficial effects on an AD-like phenotype and associated dysbiosis. These investigations highlight the effects of terpenes as environmental compounds in the prevention and/or control of atopic skin disease.

Artificial Intelligence‐Enhanced “Photonic Nose” for Mid‐Infrared Spectroscopic Analysis of Trace Volatile Organic Compound Mixtures

AbstractMolecular identification of volatile organic compounds (VOCs) plays an important role in various applications including environmental monitoring and smart farming. Mid‐infrared (MIR) fingerprint absorption spectroscopy is a powerful tool to extract chemical‐specific features for gas identification. However, the detection and recognition of trace VOC gas mixtures remain challenging due to their intrinsic weak light–matter interaction and highly overlapped absorption spectra. Here, an artificial intelligence‐enhanced “photonic nose” for MIR spectroscopic analysis of trace VOC gas mixtures is proposed. To enhance the sensing performance by increasing bandwidth and sensitivity, the “photonic nose” is designed to employ coupled multi‐resonant plasmonic nanoantennas to cover MIR molecular fingerprints, coated with metal–organic frameworks as the gas enrichment layer. Low limits of detection are achieved (IPA: 1.99 ppm, ethanol: 3.43 ppm, and acetone: 9.82 ppm). With machine learning, a high classification accuracy of 100% is realized for 125 mixing ratios (IPA, ethanol: both 5 concentrations, 0–130 ppm; acetone: 5 concentrations, 0–201 ppm), and low‐deviation component concentration predictions of root‐mean‐squared error within 10 ppm are achieved for IPA and ethanol (both 0–130 ppm) under interference from 50 ppm acetone. The work paves the way for intelligent sensing platforms for environmental monitoring and smart framing.

An original device to assess the respiratory impact of indoor air VOCs mixture using an in vitro approach

Exposure to indoor air pollution, particularly volatile organic compounds (VOCs), has been recognized as a risk factor in the development of respiratory and allergic diseases. VOCs are mainly emitted continuously at low concentrations from construction furniture and decoration products. Measurement campaigns carried out in new dwellings in France have shown that aldehydes predominate with a tendency to decrease formaldehyde concentrations and to increase those in hexanal. As the main route of VOCs exposure is inhalation, this project assessed the impact of a mixture of 17 VOCs representative of indoor air (in quality and quantity) on respiratory health using an in vitro approach. This original work was based on the set-up of an experimental device, combining a gas generation and dilution bench and exposure to the air-liquid interface (ALI) adapted to the reconstructed human airway epithelium model. The VOC mixture was enriched with formaldehyde or hexanal in different proportions (from 20 to 240 µg.m−3) to study the biological impact of these aldehydes after repeated exposures of airway epithelium. After examination of the stability of the VOC concentrations in generated mixtures and the found of the optimal operating conditions for the dynamic gas generating system, the gaseous mixtures were distributed to the epithelium using the ALI exposure system providing direct contact between the epithelium and the tested mixtures. Our device lead to reproduce real conditions of human exposure. The results showed that the inflammatory response, assessed by the production of four cytokines, varied according to the nature of the aldehyde present in the VOC mixture (formaldehyde or hexanal), its concentration, and the duration and number of exposures applied. The most original and innovative results concern those obtained with hexanal, pollutant under-researched. Our results showed that this aldehyde could pose risks to respiratory health.

Investigation of sorptive interactions between volatile organic compounds and supramolecules at dynamic oscillation using bulk acoustic wave resonator virtual sensor arrays

Supramolecules are considered as promising materials for volatile organic compounds (VOCs) sensing applications. The proper understanding of the sorption process taking place in host-guest interactions is critical in improving the pattern recognition of supramolecules-based sensing arrays. Here, we report a novel approach to investigate the dynamic host-guest recognition process by employing a bulk acoustic wave (BAW) resonator capable of producing multiple oscillation amplitudes and simultaneously recording multiple responses to VOCs. Self-assembled monolayers (SAMs) of β-cyclodextrin (β-CD) were modified on four BAW sensors to demonstrate the gas-surface interactions regarding oscillation amplitude and SAM length. Based on the method, a virtual sensor array (VSA) type electronic nose (e-nose) can be realized by pattern recognition of multiple responses at different oscillation amplitudes of a single sensor. VOCs analysis was realized respectively by using principal component analysis (PCA) for individual VOC identification and linear discriminant analysis (LDA) for VOCs mixtures classification.

Associations of exposure to volatile organic compounds with sleep health and potential mediators: analysis of NHANES data.

The effect of environmental pollution on sleep has been widely studied, yet the relationship between exposure to volatile organic compounds (VOCs) and sleep health requires further exploration. We aimed to investigate the single and mixed effect of urinary VOC metabolites on sleep health and identify potential mediators. Data for this cross-sectional study was collected from the National Health and Nutrition Examination Surveys (NHANES) (2005-2006, 2011-2014). A weighted multivariate logistic regression was established to explore the associations of 16 VOCs with four sleep outcomes. Following the selection of important VOCs through the least absolute shrinkage and selection operator (LASSO) regression, principal component analyses (PCA), weight quantile sum (WQS), and Bayesian kernel machine regression (BKMR) analyses were conducted to explore the associations between exposure to single and mixed VOCs and sleep outcomes, as well as identify the most contributing components. A mediation analysis was performed to explore the potential effect of depression scores. Of the 3,473 participants included in the study, a total of 618 were diagnosed with poor sleep patterns. In logistic regression analyses, 7, 10, 1, and 5 VOCs were significantly positively correlated with poor sleep patterns, abnormal sleep duration, trouble sleeping, and sleep disorders, respectively. The PCA analysis showed that PC1 was substantially linked to a higher risk of poor sleep patterns and its components. The WQS model revealed a positive association between VOC mixture of increased concentrations and poor sleep patterns [OR (95% CI): 1.285 (1.107, 1.493)], abnormal sleep duration [OR (95% CI): 1.154 (1.030, 1.295)], trouble sleeping [OR (95% CI): 1.236 (1.090, 1.403)] and sleep disorders [OR (95% CI): 1.378 (1.118, 1.705)]. The BKMR model found positive associations of the overall VOC exposure with poor sleep patterns, trouble sleeping, and sleep disorders. PCA, WQS, and BKMR models all confirmed the significant role of N-acetyl-S-(N-methylcarbamoyl)-l-cysteine (AMCC) in poor sleep patterns and its components. The depression score was a mediator between the positive VOC mixture index and the four sleep outcomes. Exposure to single and mixed VOCs negatively affected the sleep health of American population, with AMCC playing a significant role. The depression score was shown to mediate the associations of VOC mixtures with poor sleep patterns and its components.

Impact of Different Carbon Sources on Volatile Organic Compounds (VOCs) Produced during Fermentation by Levilactobacillus brevis WLP672 Measured Using Proton Transfer Reaction Time-of-Flight Mass Spectrometry (PTR-ToF-MS).

Bacterial fermentation is considered to be a cost-effective means of generating desired flavour compounds from plant-based substrates. However, the wide range of substrates present in plants makes it challenging to understand how individual components impact on flavour volatile organic compound (VOC) production. To simplify this, a defined medium can be used to better understand VOCs production with regard to individual compounds. In the current study, the VOCs produced by the lactic acid bacterium, Levilactobacillus brevis WLP672, growing in a defined medium containing different carbon sources (either glucose (DM), fructose (DMFr) or citrate (DMCi)) under a range of fermentation conditions (time: 0, 7, and 14 days; and temperature: 25 and 35 °C) were assessed using proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS). Among the detected mass peaks (m/z), after 7 days of fermentation, the concentrations of m/z 45.033 (t.i. acetaldehyde), m/z 49.011 (t.i. methanethiol), and m/z 89.060 (t.i. ethyl acetate) were significantly (p < 0.05) higher in DM at 35 °C than all other treatments at either temperature. The knowledge obtained will help to produce desirable LAB fermentation flavour VOCs or VOC mixtures that could be used in developing plant-based analogues with acceptable sensory properties.

Bispidine Based Hg(II) 1D Coordination Polymers of Helical Topology: Stability, Selective Adsorption and 1D to 2D Dimensionality Change Via SC-to-SC Transformation.

Bispidine based Hg(II) coordination polymers of helical topology CP-MeOH and CP-EtOH are almost isostructural (they mainly differ for the solvent included in their lattice and by a small % in unit cell parameters) but they differ for everything else: i) their intrinsic stability, ii) their ability to adsorb solvents upon prior evacuation, iii) their accessible structural transformations. In particular, one of the two starting materials, once evacuated, is capable to adsorb methanol from atmospheres containing binary and ternary mixtures of volatile organic compounds (MeOH, CHCl3 and EtOH) under ambient conditions (25 °C, 1 atm) and with a marked selectivity. The other one is not, but undergoes a 1D to 2D dimensionality change which can be monitored in situ by SC-XRD through a SC-to-SC process.

Sexual dimorphism association of combined exposure to volatile organic compounds (VOC) with kidney damage

BackgroundEpidemiological evidence emphasizes air pollutants' role in chronic kidney disease (CKD). Volatile organic compounds (VOCs) contribute to air pollution, yet research on VOCs and kidney damage, especially gender disparities, is limited. MethodsThis study analyzed NHANES data to explore associations between urinary VOC metabolite mixtures (VOCMs) and key kidney-related parameters: estimated glomerular filtration rate (eGFR), albumin-to-creatinine ratio (ACR), chronic kidney disease (CKD), and albuminuria. Mediation analyses assessed the potential mediating roles of biological aging (BA) and serum albumin in VOCM mixtures' effects on kidney damage. Sensitivity analyses were also conducted. ResultsThe mixture analysis unveiled a noteworthy positive association between VOCM mixtures and the risk of developing CKD, coupled with a significant negative correlation with eGFR within the overall participant cohort. These findings remained consistent when examining the female subgroup. However, among male participants, no significant link emerged between VOCM mixtures and CKD or eGFR. Furthermore, in both the overall and female participant groups, there was an absence of a significant correlation between VOCM mixtures and either ACR or albuminuria. On the other hand, in male participants, while no significant correlation was detected with albuminuria, a significant positive correlation was observed with ACR. Pollutant analysis identified potential links between kidney damage and 1,3-butadiene, toluene, ethylbenzene, styrene, xylene, acrolein, crotonaldehyde and propylene oxide. Mediation analyses suggested that BA might partially mediate the relationship between VOCM mixtures and kidney damage. ConclusionThe current findings highlight the widespread exposure to VOCs among the general U.S. adult population and indicate a potential correlation between exposure to VOC mixtures and compromised renal function parameters, with notable gender disparities. Females appear to exhibit greater sensitivity to impaired renal function resulting from VOCs exposure. Anti-aging treatments may offer some mitigation against kidney damage due to VOCs exposure.

Time-Resolved Ion Mobility Spectrometry with a Stop Flow Confined Volume Reaction Region.

An ion source concept is described where the sample flow is stopped in a confined volume of an ion mobility spectrometer creating time-dependent patterns of ion patterns of signal intensities for ions from mixtures of volatile organic compounds and improved signal-to-noise rate compared to conventional unidirectional drift gas flow. Hydrated protons from a corona discharge were introduced continuously into the confined volume with the sample in air at ambient pressure, and product ions were extracted continuously using an electric field for subsequent mobility analysis. Ion signal intensities for protonated monomers and proton bound dimers were measured and computationally extracted using mobilities from mobility spectra and exhibited distinct times of appearance over 30 s or more after sample injection. Models, and experimental findings with a ternary mixture, suggest that the separation of vapors as ions over time was consistent with differences in the reaction rate for reactions between primary ions from hydrated protons and constituents and from cross-reactions that follow the initial step of ionization. The findings suggest that the concept of stopped flow, introduced here for the first time, may provide a method for the temporal separation of atmospheric pressure ions. This separation relies on ion kinetics and does not require chromatographic technology.

Biofiltration of toluene and ethyl acetate mixture by a fungal-bacterial biofilter: Performance and community structure analysis

The inhibitory effect of hydrophilic volatile organic compounds (VOCs) on hydrophobic VOCs removal was found to be efficiently reduced by the fungal-bacterial biofilters (F&B-BFs) developed in the present study. Overall, the toluene and ethyl acetate mixture removal efficiencies (REs) and elimination capacities (ECs) of F&B-BFs were superior to those of bacterial biofilters (B-BFs). The REs for toluene and ethyl acetate were 32.5 ± 0.8 % and 74.6 ± 1.0 %, respectively, for F&B-BFs, in comparison to 8.0 ± 0.3 % and 60 ± 1.3 % for B-BFs. The ECs for toluene and ethyl acetate were 13.0 g m−3 h−1 and 149.2 g m−3 h−1, respectively, for the F&B–BF, compared to 3.2 g m−3 h−1 and 119.6 g m−3 h−1 for the B-BFs. This was achieved at a constant empty bed residence time (EBRT) of 45 s. F&B-BFs exhibited a superior mineralization efficiencies (MEs) compared to B-BFs for a VOC mixture of toluene and ethyl acetate (≈36.1 % vs ~ 29.6 %). This is attributed to the direct capture of VOCs by the presence of fungi, increased the contact time between VOCs and VOCs-degrading bacteria, and even distribution of VOCs-degrading bacteria in the F&B-BFs. Moreover, compared with B-BFs, the coupling effect of genus Pseudomonas degradation, and unclassified_f_Herpotrichiellaceae and unclassified_p_Ascomycota adsorption of F&B–BF resulted in a reduction in the impact of the presence of hydrophilic VOCs on the removal of hydrophobic VOCs, thereby enhancing the biofiltration performance of mixtures of hydrophilic and hydrophobic VOCs.

Development of 2D CuO based chemiresistive sensors for detecting binary mixture of volatile organic compounds and investigation of the adsorption kinetics via Eley-Rideal mechanism

Detection of mixture of volatile organic compounds (VOCs) and prediction of the individual components present in it plays a significant role in various applications arching from health care to environmental monitoring. In this research, CuO nanoflakes of thickness ∼ 35 nm, and direct and indirect bandgaps of 1.8 and 1.3 eV, respectively, were synthesized hydrothermally. Chemiresistive sensors fabricated using the CuO nanoflakes were tested for individual gases and all combinations of binary mixtures of five VOCs namely acetone, acetonitrile, isopropanol, methanol, and toluene at 300 °C which was found to be the optimum temperature of operation for all the five VOCs. The response of CuO was found to range from 58–140 %, 35–95 %, 23–98 %, 17–50 %, and 5–30 % for 25–75 ppm of toluene, methanol, isopropanol, acetonitrile, and acetone respectively. The response was found to be an addition of the responses of CuO to the two individual VOCs when the sensing layer was exposed to the mixture of two at 300 ℃. The adsorption kinetics of the metal oxide for mixture of gases is explained using the Eley-Rideal mechanism. Also, the random forest (RF) algorithm was employed to identify the individual VOCs and their respective concentrations just by taking inputs from the response transients of CuO nanoflakes to the binary mixtures of VOCs and was found to exhibit 93.8 % accuracy.

Effect of the component and the concentration ratio on the removal of volatile organic compound mixtures by non-thermal plasma

The feasibility and efficiency of the degradation of volatile organic compounds (VOCs) by non-thermal plasma (NTP) has been extensive investigated and proved in laboratory experiments with single target component. In practical, multicomponent VOCs are emitted during industrial production. It is urgent need to study the abatement of multicomponent VOCs to evaluate the effectiveness of NTP technology in application, and explore the impact of interactions between VOCs components on degradation efficiency. This study focused on the degradation of VOCs mixtures composed of toluene (TOL), acetone (AC), and ethyl acetate (EA) by dielectric barrier discharge (DBD) plasma in room temperature. Through changing the target gas in turn and the concentration ratio of additive gas in binary mixture, the influence of the composition and the concentration ratio of the additive gases on the target gas degradation have been investigated by comparing the decomposition of the single compound. The results showed that AC and EA had little or no inhibitory effect on degradation of TOL. When AC was added and degraded together with TOL, the degradation rate of TOL remained almost unchanged with slight fluctuations in the range of 75.3 ± 1.0% as the ratio of added AC increased. However, TOL significantly inhibited the degradation of EA and AC, and more seriously on AC. When the ratio of added TOL increased, the degradation rates of EA or AC changed from 41.1% or 34.5% to 29.8% or 12.2%, which were 11.3% or 22.3% reduced respectively. It is indicated that there was a mutual inhibitory effect between the AC and EA when they were degraded together, and a stronger inhibitory effect of EA on AC was observed. When the ratio of added AC to EA changed from 0:1 to 3:1, the degradation rate of EA decreased by 9.5%, from 49.8% to 40.3%. When the ratio of added EA to AC changed from 0:1 to 3:1, the degradation rate of AC decreased by 16.0%, from 37.9% to 21.9%.

The application of PTR-MS and non-targeted analysis to characterize VOCs emitted from a plastic recycling facility fire.

On April 11th, 2023, the My Way Trading (MWT) recycling facility in Richmond, Indiana caught fire, mandating the evacuation of local residents and necessitating the U.S. Environmental Protection Agency (EPA) to conduct air monitoring. The EPA detected elevated levels of plastic combustion-related air pollutants, including hydrogen cyanide and benzene. We aimed to identify these and other volatile organic compounds (VOCs) present as well as to identify the potential hazard of each compound for various human health effects. To identify the VOCs, we conducted air monitoring at sites within and bordering the evacuation zone using proton transfer reaction mass spectrometry (PTR-MS) and non-targeted analysis (NTA). To facilitate risk assessment of the emitted VOCs, we used the EPA Hazard Comparison Dashboard. We identified 46 VOCs, within and outside the evacuation zone, with average detection levels above local background levels measured in Middletown, OH. Levels of hydrogen cyanide and 4 other VOCs were at least 1.8-fold higher near the incidence site in comparison to background levels and displayed unique temporal and spatial patterns. The 46 VOCs identified had the highest hazardous potential for eye and skin irritation, with approximately 45% and 39%, respectively, of the VOCs classified as high and very high hazards for these endpoints. Notably, all detected VOC levels were below the hazard thresholds set for single VOC exposures; however, hazard thresholds for exposure to VOC mixtures are currently unclear. This study serves as a proof-of-concept that PTR-MS coupled with NTA can facilitate rapid identification and hazard assessment of VOCs emitted following anthropogenic disasters. Furthermore, it demonstrates that this approach may augment future disaster responses to quantify additional VOCs present in complex combustion mixtures.