Kinds Of Volatile Organic Compounds Research Articles

Target discrimination, concentration prediction, and status judgment of electronic nose system based on large-scale measurement and multi-task deep learning

Pattern recognition is the core component of the electronic nose (E-nose). Traditional machine learning algorithms highly rely on the feature data selected manually for model training and testing. A complete experiment must be performed before the data can be further processed. To realize the automatic extraction of response features and simplify the model’s training and application process, a multi-task convolutional neural network (MTL-CNN) with a dual-block knowledge-sharing structure is designed to train a model for the E-nose system. This model can simultaneously perform three different classification tasks, for the purposes of target discrimination, concentration prediction, and state judgment. Only a few consecutive seconds of response data are needed to be input into the trained model to obtain various information about the E-nose. With the utilization of an unmanned gas-sensing test system, large-scale measurements of the E-nose can be carried out automatically. A baseline tracking algorithm (BTA) is designed based on the relative changes of short-term data, reducing the impact of long-term shifts. Over thousands of gas response processes and more than 10 million sensing data have participated in the training of the deep learning model. The 5-fold cross-validation method shows that the fully trained model has an outstanding generalization performance. After the baseline is tracked automatically, the accuracy of three tasks towards 12 kinds of volatile organic compounds (VOCs) is about 95% (type recognition: 95.2%, concentration prediction: 92.1%, status judgment: 97.3%) using only 4 s of sensing data during the response status of the E-nose. Our work shows the distinct advantages of combining “big data” and “deep learning” in the gas-sensing field and further proves that the employment of MTL-CNN can significantly improve the training and application efficiency of the E-nose.

In Vitro Biological Control of Aspergillus flavus by Hanseniaspora opuntiae L479 and Hanseniaspora uvarum L793, Producers of Antifungal Volatile Organic Compounds.

Aspergillus flavus is a toxigenic fungal colonizer of fruits and cereals and may produce one of the most important mycotoxins from a food safety perspective, aflatoxins. Therefore, its growth and mycotoxin production should be effectively avoided to protect consumers’ health. Among the safe and green antifungal strategies that can be applied in the field, biocontrol is a recent and emerging strategy that needs to be explored. Yeasts are normally good biocontrol candidates to minimize mold-related hazards and their modes of action are numerous, one of them being the production of volatile organic compounds (VOCs). To this end, the influence of VOCs produced by Hanseniaspora opuntiae L479 and Hanseniaspora uvarum L793 on growth, expression of the regulatory gene of the aflatoxin pathway (aflR) and mycotoxin production by A. flavus for 21 days was assessed. The results showed that both yeasts, despite producing different kinds of VOCs, had a similar effect on inhibiting growth, mycotoxin biosynthetic gene expression and phenotypic toxin production overall at the mid-incubation period when their synthesis was the greatest. Based on the results, both yeast strains, H. opuntiae L479 and H. uvarum L793, are potentially suitable as a biopreservative agents for inhibiting the growth of A. flavus and reducing aflatoxin accumulation.

Biological treatment of volatile organic compounds (VOCs)-containing wastewaters from wet scrubbers in semiconductor industry

This study investigated biological treatment for two kinds of volatile organic compounds (VOCs)-containing wastewaters collected from wet scrubbers in a semiconductor industry. Batch test results indicated that one wastewater containing highly volatile organic compounds was not suitable for aerated treatment conditions while the other containing much lower volatile organic compounds was suitable for aerobic treatment. Accordingly, two moving bed bioreactors, by adding commercial biocarrier BioNET, were operated under aerobic and anoxic conditions for treating low volatility wastewater (LVW) and high volatility wastewater (HVW), respectively. During 280 days of operation, the aerobic LVW bioreactor attained the highest chemical oxygen demand (COD) removal rate of 98.9 mg-COD/L/h with 81% of COD removal efficiency at hydraulic retention time (HRT) of 1 day. The anoxic HVW bioreactor performed above 80% of COD removal efficiency with the highest COD removal rate of 16.5 mg-COD/L/h at HRT of 2 days after 380 days of operation. The specific COD removal rates at different initial substrate-to-biomass (S0/X0) ratios, using either suspended sludge or microorganisms attached onto BioNET from both bioreactors, followed the Monod-type kinetics, while the half-saturation coefficients were generally higher for the microorganisms onto BioNET due presumably to relatively poor mass transfer efficiency. Based on the results of microbial community analysis using the next generation sequencing technique, the dominant communities of suspended sludge and BioNET, including nitrifiers, denitrifiers, and degraders for polycyclic aromatic hydrocarbons, were similar in the corresponded bioreactors, but microbial community shifts were observed with increased organic loadings.

Emissions Characterization of Volatile Organic Compounds and Health Risk Assessment in Two Fresh Furniture

The emissions of volatile organic compounds (VOCs) from two common furniture products including a dressing stool and a bedside cabinet were measured in an environmental chamber. The VOCs were collected by Tenax-TA tubes and measured by thermal desorption and gas chromatography (FID). 19 kinds of VOCs were quantitatively analyzed by the external standard method. The results showed that the VOCs concentrations emitted from the two kinds of furniture were quite different, but benzene homologues were the principal pollutant. The concentrations of VOCs released from the furniture showed decreases exponentially with time and it could be fitted well by a double-exponential decay model. The concentrations of VOCs increased rapidly and reached the maximums at around 1 or 2 h, and then declined with the slowdown of the release rate. Moreover, the potential VOCs release could be evaluated by the release parameters of this model. In addition, health risk assessment of benzene released from dressing stools and bedside cabinets was performed. The risk of benzene released from two kinds of furniture decreased with time. The R value of benzene released from the dressing stool at 72 h remained at least two orders of magnitude larger than 1 × 10−6, indicating a high risk of carcinogenesis. The study will provide a reliable reference in assessing VOCs emissions and health risks in fresh furniture.

Highly responsive triethylamine vapor sensor based on a perylene diimide-polydiacetylene system via heat-induced tuning of the molecular packing approach

Triethylamine (TEA) is a kind of volatile organic compound (VOC) and the most preferred organic amine as a reagent, catalyst, and organic solvent in industrial production. However, in addition to its pungency odorous characteristic, TEA can have deleterious short-term and long-term effects on human health and the environment. Therefore, it is important to design and develop a highly sensitive and selective TEA sensor that allows for fast and timely detection. Herein, we report a highly sensitive TEA sensor based on perylene diimide-polydiacetylene (PDI-PDA2) nanofibers. A strategy of UV-induced polymerization under continuous heating (to 130 °C) was adopted to trap and preserve the molecular orientation of the post-crystal-crystal phase transition by virtue of a robust PDA backbone. Analyzing the molecular–packing–performance relationship revealed a dramatic enhancement of TEA vapor detection response due to crystal-crystal transition in PDI-PDA solid. The lower LUMO energy level for PDI-PDA2 is proved to enhance the sensing performance by enabling efficient charge mobility between PDI and TEA. We believe that this study will encourage further research to design improved VOC sensing devices based on the molecular–packing arrangement.

New designed coupling agents for silica used in green tires with low VOCs and low rolling resistance

Bis-(γ-triethoxysilylpropyl)-tetrasulfide TESPT (Si69) is the most popular silane coupling agent for green tires. However, a large amount of alcohol vapours (a kind of volatile organic compounds (VOCs)) release when it is used for tire production, which can make the process harmful to tire quality and people’s health. In this work, Mx-Si69 (x = 1, 2, 3, 4, 5, 6), a series of silane coupling agents were successfully synthesized by transesterification of fatty alcohol polyoxyethylene ether-9 (AEO-9) with Si69. A series of Si69 molecule grafted with one to six fatty alcohol polyoxyethylene ether chains (the long alkoxy chain) (named as M1-Si69 to M6-Si69) were produced. The FT-IR and 1H NMR results revealed that six coupling agents named M1-Si69 ~ M6-Si69 could be obtained by adjusting the molar ratio of the reactive monomers. So, the VOCs emission could be reduced by 37.5%~100% theoretically because of the long chain reaction products. The FT-IR and TGA results demonstrated that Mx-Si69 could successfully modify silica. Then, silica/rubber compounds were prepared by adding these low VOCs coupling agents namely M1-Si69 ~ M6-Si69. The dynamic and static mechanical results indicated that silica/rubber compound made by adding M2-Si69 had the lowest Heat-Build up, the best wet skid resistance, and extremely low rolling resistance (it can save more than 20% energy consumption than Si69).

Fabrication and electrochemical property of La0.8Sr0.2MnO3 and (ZrO2)0.92(Y2O3)0.08 interface for trace alcohols sensor

Abstract A mixed potential type alcohols gas sensor based on an yttrium stabilized zirconia (YSZ) electrolyte and an La0.8Sr0.2MnO3 (LSM) sensing electrode was fabricated. The influences of YSZ-LSM interface on sensing performance were studied by multiple methods including X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), thermogravimetric analysis and differential scanning calorimetry (TG-DSC) and electrochemical impendence spectroscopy (EIS). The sensor with 1150 °C-sintered interface showed an ultralow detection limit of 50 ppb alcohols (methanol and ethanol) at 500 °C in air. The response voltage was independent of water, CO, CO2 and NOx. The sensor exhibited a reasonable selectivity towards alcohols under the existence of several kinds of volatile organic compounds. Meanwhile, the sensor showed a good repeatability and a suitable long-term stability. Based on the polarization curves and EIS results, a mixed potential mechanism was proposed. These results demonstrate the promising potential of using the LSM-based sensor for human exhale test.

VOCs pollution characteristics and potential of ozone generation in Kaifeng City

In recent years, the exhausted gas from factories has become an important part of environmental pollution in Kaifeng City. Air samples were collected for 57 kinds of volatile organic compounds (VOCs) and 13 kinds of aldehydes and ketones from the Cancer Hospital of Kaifeng city between May and October 2019. The pollutants were measured by gas chromatography-mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC) technique. Combined with the 8-hour automatic monitoring data of air ozone automatic monitoring at this sampling site, a total of 31 observations on volatile organic compounds (VOCs) were carried out over between May and October 2019. The results showed that the average concentration of VOCs was in the order of oxygen-containing organic matters > alkanes > olefins > aromatic hydrocarbons > alkynes. Using SPSS26 statistical software, representative key species were selected from VOCs, and correlation analysis was conducted with ozone concentration and meteorological factors. The ozone concentration was significantly correlated with air temperature. Acrolein & propionaldehyde, acetaldehyde, and formaldehyde, had a significant negative correlation with ethylene and ethane. The highest ethylene and ethane concentrations appeared when there was west wind, while toluene showed a significantly high value in the southwest wind. The oxygenated organics had obvious wind direction characteristics and the four kinds of oxygenated organics were rarely affected by the west, northwest and north winds.

Simultaneous removal of ammonia and volatile organic compounds from composting of dead pigs and manure using pilot-scale biofilter

ABSTRACT Odor emission is one of the most common problems associated with dead animals composting. Biofiltration treatment for eliminating exhaust odors formed during dead pigs and manure composting has been studied. The composting and biofiltration process consisted of two series of tests. Composting experimental trials lasted 6 weeks, and composting was performed using six pilot-scale reactor vessels. A total of 37 kinds of volatile organic compounds (VOCs) present in the air were identified, and temporal variations were determined during the 42 days of composting. Dimethyl sulfide (DMS), dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS), and trimethylamine (TMA) were identified as the main odors VOCs component according to odor active values (OAVs). Nine biofilter vessels containing mature compost were used in studying the effect of different (30, 60, and 100 s) empty bed retention times (EBRT) on the simultaneous removal efficiencies (REs) of NH3, DMS, DMDS, DMTS, and TMA. Results indicated that the inlet concentration of NH3 applied was 12–447 mg m−3, and the average removal efficiencies were 85.4%, 88.7%, and 89.0% for EBRTs of 30, 60, and 100 s, respectively. The average REs of DMS, DMDS, DMTS, and TMA were 79.2%–95.4%, 81.9%–94.0%, 76.7%–99.1%, and 92.9%–100%, respectively, and their maximum elimination capacity (ECs) were 220, 1301, 296, and 603 mg m−3 h−1, respectively. The optimal EBRT for the stimulation removal of NH3, DMS, DMDS, DMTS, and TMA was 60 s. Implications: Dimethyl sulfide (DMS), dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS), and trimethylamine (TMA) were identified as the main odors VOCs component during dead pigs and manure composting. Biofilter with mature as media can be used to stimulation remove NH3, DMS, DMDS, DMTS, and TMA, the optimal empty bed retention times EBRT was 60 s.

A polythiophene/UiO-66 composite coating for extraction of volatile organic compounds migrated from ion-exchange resins prior to their determination by gas chromatography

A Poly (3,4-ethylenedioxothiophene) (PEDOT)/UiO-66 composite was electrodeposited on an etched stainless-steel wire as head-space solid-phase microextraction (HS-SPME) coating. A robust, well controlled thickness, and uniform coating of metal organic framework composites can be realized by the electrodeposited strategy. The incorporated UiO-66 not only enhanced the uniformity and stability of the composite coating, but also effectively decreased the stacking phenomenon of PEDOT and improved its extraction efficiency, which was over 100 times higher than that of the PEDOT coating without UiO-66. The composite coating was used to enrich seven types of volatile organic compounds (VOCs) in ion-exchange resins, including methyl cyclohexane, benzene, toluene, ortho-xylene, styrene, para-xylene and divinyl-benzene. The results of adsorption isotherm analysis showed that π stacking effect played dominant role between the composite coating and VOCs in the extraction process. The composite coating was characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared and thermogravimetric analysis, respectively. A determination method for seven kinds of VOCs was established by HS-SPME coupled with gas chromatography-flame ionization detection (GC-FID). Under the optimal experimental conditions, the detection linear range (LRs) was 0.09-100 ng mL−1, and the detection limit (LODs) was 0.03-0.06 ng mL−1 (S/N = 3). The method was applied for the migration detection of VOCs in four types of ion-exchange resin, which showed satisfactory recovery (84.5-117.2%).

Facile Design and Hydrothermal Synthesis of In2O3 Nanocube Polycrystals with Superior Triethylamine Sensing Properties.

Triethylamine (TEA), a typical kind of volatile organic compound, is widely used as an industrial solvent, which is a threat to environment and human health. In this paper, a novel In2O3 nanocube gas sensing material with high sensing performances was synthesized through a simple one-pot hydrothermal method. The gas sensing test results are satisfactory such that the single phase of In2O3 nanocubes even exhibits a quite higher response of 12–10 ppm of TEA at a lower temperature (180 °C) than many conventional In2O3-based complexes and maintains high consistency in morphology and stability after the consecutive tests of 2 months. This work provides a facile and quite effective gas sensing material for TEA gas monitoring with high sensitivity and stability and good selectivity at lower working temperature that can be prepared in batch and further used as templates.

A cataluminescence sensor for the detection of trichloroethylene based on PEG200/ZnO nanocomposite

The content of volatile organic compounds (VOCs) in the atmosphere will endanger the health and safety of human beings which makes it very important to develop a simple and rapid method for the determination of gas pollutants. Based on this, a new type of gas sensor was proposed for the detection of trichloroethylene in air. PEG200/ZnO nanocomposite were prepared by hydrothermal method. The materials were characterized by scanning electron microscope, X-ray energy spectrum and fourier infrared spectrum. The high selectivity of the materials was verified by using the cataluminescence (CTL) intensity of 9 kinds of VOCs on the surface of the materials as a reference. The results show that trichloroethylene can produce CTL response on the surface of PEG200/ZnO nanocomposite. Temperature, air flow rate and detector concentration all have certain effects on the CTL intensity. By comparing the CTL intensity under different reaction conditions, it is found that the suitable temperature and air flow rate are 120 °C, 180 mL/min and there is a good linear relationship between the relative CTL intensity and the concentration of the detected substance (y = 28.588 x - 285.56, R=0.9593). The gas sensor has the advantage of rapid response, and trichloroethylene can produce the maximum CTL on the surface of the material within 3 ~ 5 s.

Effective low‐temperature catalytic abatement of benzene over porous Mn‐Ni composite oxides synthesized via the oxalate route

AbstractBACKGROUNDBenzene (C6H6) is a typical kind of volatile organic compound (VOC) which can exert great harm to both human health and the environment, and, thus, which needs to be eliminated before its emission. In this work, porous manganese–nickel (Mn‐Ni) composite oxide catalysts were synthesized through the oxalate route and applied to thermal catalytic oxidation of C6H6. By means of activity tests and relative physico‐chemical characterizations, the factors affecting the activity of those Mn‐Ni composite oxides were explored.RESULTSNitrogen (N2)‐adsorption/desorption and X‐ray photoelectron spectroscopy (XPS) measurements indicated that the Brunauer–Elmett–Teller (BET) surface area and the content of surface‐adsorbed oxygen species were increased due to the addition of Ni into Mn oxide (MnOx). Meanwhile, the oxygen mobility and reducibility also were improved in the Mn‐Ni composite oxides. Accordingly, compared with MnOx, the Mn‐Ni catalysts showed higher activity for thermal catalytic oxidation of C6H6. Moreover, porous Mn‐Ni composite oxides with a Mn:Ni molar ratio of 4:1 (Mn4Ni1) displayed the best catalytic activity. Further investigation indicated that the excellent catalytic performance of Mn4Ni1 composite oxides could be ascribed mainly to the larger BET surface area and the richer content of surface‐adsorbed oxygen species, as well as stronger oxygen mobility and better reducibility compared with other Mn‐Ni catalysts.CONCLUSIONSThe Mn4Ni1 composite oxides showed a lowest T90 value of 172 °C (C6H6 concentration 200 ppm, WHSV 60 000 mL g−1 h−1) among all of the obtained Mn‐Ni composite oxides. Moreover, it also exhibited favourable catalytic stability at 210 °C in the presence or absence of moisture. © 2019 Society of Chemical Industry

Molecular characteristics and diurnal variations of organic aerosols at a rural site in the North China Plain with implications for the influence of regional biomass burning

Abstract. Field burning of crop residue in early summer releases a large amount of pollutants into the atmosphere with significant impacts on the air quality and aerosol properties in the North China Plain (NCP). In order to investigate the influence of this regional anthropogenic activity on molecular characteristics of organic aerosols, PM2.5 filter samples were collected with a 3 h interval at a rural site of NCP from 10 to 25 June 2013 and analyzed for more than 100 organic tracer compounds, including both primary (n-alkanes, fatty acids/alcohols, sugar compounds, polycyclic aromatic hydrocarbons, hopanes, and phthalate esters) and secondary organic aerosol (SOA) tracers (phthalic acids, isoprene-, α-/β-pinene, β-caryophyllene, and toluene-derived products), as well as organic carbon (OC), elemental carbon (EC), and water-soluble organic carbon (WSOC). Total concentrations of the measured organics ranged from 177 to 6248 ng m−3 (mean 1806±1308 ng m−3) during the study period, most of which were contributed by sugar compounds, followed by fatty acids and fatty alcohols. Levoglucosan (240±288 ng m−3) was the most abundant single compound and strongly correlated with OC and WSOC, suggesting that biomass burning (BB) is an important source of summertime organic aerosols in this rural region. Based on the analysis of fire spots and backward trajectories of air masses, two representative periods were classified, which are (1) Period 1 (P1), 13 June 21:00–16 June at 15:00 CST (China Standard Time), when air masses were uniformly distributed from the southeast part of NCP, where intensive open-field biomass burning occurred; and (2) Period 2 (P2), 22 June at 12:00 to 24 June at 06:00 CST, which is representative of local emission. Nearly all the measured PM components showed much higher concentrations in P1 than in P2. Although n-alkanes, fatty acids, and fatty alcohols presented similar temporal–diurnal variations as those of levoglucosan throughout the entire period, their molecular distributions were more dominated by high molecular weight (HMW) compounds in P1, demonstrating an enhanced contribution from BB emissions. In contrast, intensive BB emission in P1 seems to have limited influence on the concentrations of polycyclic aromatic hydrocarbons (PAHs), hopanes, and phthalate esters. Both 3-hydroxyglutaric acid and β-caryophyllinic acid showed strong linearly correlations with levoglucosan (R2=0.72 and 0.80, respectively), indicating that BB is also an important source for terpene-derived SOA formation. A tracer-based method was used to estimate the distributions of biomass-burning OC, fungal-spore OC, and secondary organic carbon (SOC) derived from isoprene, α-/β-pinene, β-caryophyllene, and toluene in the different periods. The results showed that the contribution of biomass-burning OC to total OC in P1 (27.6 %) was 1.7 times that in P2 (17.1 %). However, the contribution of SOC from oxidation of the four kinds of volatile organic compounds (VOCs) increased slightly from 16.3 % in P1 to 21.1 % in P2.

Evaluation of a pilot-scale bio-trickling filter as a VOCs control technology for the chemical fibre wastewater treatment plant.

The performance of lab- and pilot-scale bio-trickling filters (BTFs) for the treatment of emissions from a chemical fibre wastewater treatment plant was investigated. These systems were installed mainly to demonstrate the effectiveness of bio-trickling technologies in purifying exhaust gases containing different kinds of volatile organic compounds (VOCs). Results showed that 12 days more were necessary for the pilot-scale BTF to start up successfully than the lab-scale one. Both the lab- and pilot-scale BTFs exhibited contaminant removal efficiency higher than 90% at an empty bed residence time of 59 s, corresponding to gas flow of 0.2 m3 h-1 and 550 m3 h-1, respectively. The reduction of the microelement in the nutrient solution had little effect on the performance of the pilot-scale BTF. The abundance and diversity of the microorganism analysis showed that the diversity of the contaminants had a significant influence on the microorganism distribution in the BTF. Economic feasibility study showed that BTF might be an efficient solution for VOCs control with a lower cost than adsorption technology and regenerative catalytic oxidation.

The influence of particle morphology on the structure and mechanical properties of films cast from hybrid latexes

Two phase latex particles offer a potential route to obtain homogeneous, transparent and mechanically strong films with low minimum film formation temperature (MFFT) without the addition of any kind of volatile organic compound (VOC). In this work, we have studied how the morphology of hybrid latex particles influences the morphology and the mechanical strength of polymer films cast from latex dispersions. Hybrid particles containing a hard, high Tg seed (Styrene(S)/Acrylamide(AM), Tg = 101 °C) and a low Tg (Methyl Methacrylate(MMA)/Butyl Acrylate(BA)/Styrene(S), Tg = 13 °C) second phase polymer were synthesized. Different particle morphologies were obtained by slight variation of the amount of AM in the seed and S in the second-stage polymer. Film morphologies and properties for films cast at 60 °C were compared in order to find a link between particle morphology and film properties. Moreover, the effect of annealing temperature on film morphology was investigated. Through careful control of particle microstructure during the latex synthesis it is shown that good control over the final properties of the polymer film can be obtained, even for nominally similar polymer mixtures.

Artificial tailored catalytic activity for identification of 6 kinds of volatile organic compounds via the light-regulated electrochemical reaction

Light-regulated electrochemical reaction is confirmed to be useful to improve the classification efficiency. However, the use of different photoactive sensing materials results in time-consuming for exploring well-designed materials, besides, the light-regulated electrochemical reaction only improved the classification feature while didn't bring essential difference in the distinguish capability yet. Herein, a zirconia-based electrochemical sensor array comprised of 3 types of ZnO/In2O3 composite sensing materials is fabricated. After illumination, significantly enhancement is witnessed for the response magnitude and detection limit. Additionally, the response signal of the sensor array to part of the examined volatile organic compounds (VOCs) is selectively enhanced and 3 more disparate response patterns are generated. Through inputting all the response patterns into principle component analysis (PCA) software, 6 kinds of concerned VOCs have been fully classified. Conclusively, with utilizing sensing materials with similar composition, the fabrication process of the sensor array can be simplified. Particularly, after exposure to illumination the sensor array consisting of limited photoactive sensing materials (e.g. 3 kinds of materials) can identify even more number of gases (e.g. 6 types of VOCs). We anticipate these promising results shed light on the bright future of designing compact sensing devices for progressively smarter monitoring of concerned gas species.

Measurement of volatile organic compounds and associated risk assessments through ingestion and dermal routes in Dongjiang Lake, China

This study aims to investigate the occurrence, distribution and risk assessment of volatile organic compounds (VOCs) in Dongjiang Lake of China. Twenty two kinds of VOCs were detected, and the major VOCs were alkene compounds. The total concentration of VOCs (∑VOCs) ranged from 2.93 to 4.69 µg/L, and none of the VOCs detected in Dongjiang Lake exceeded the concentration limits set in the National Drinking Water Quality Standards (GB5749-2006) or the National Environmental Quality Standards for Surface Water (GB3838-2002) of China. Risk quotients (RQ) model, Multimedia Environment Pollutant Assessment System (MEPAS) and value of odor hazard index (OHI) were used to assess the ecological risk, lifetime carcinogenic risk and olfactory risk of VOCs in Dongjiang Lake, respectively. The RQtotal values varied from 3.95 × 10−3 to 0.34 and the RQ values for all the 22 detected VOCs in 12 sample locations of Dongjiang Lake were below 0.01, which means negligible risk to aquatic organisms. The cancerous and non-cancerous risk indices were in the range of 2.31 × 10−9–5.16 × 10−7 and 1.68 × 10−7–1.45 × 10−2, respectively. Bromodichloromethane and 1,1-dichloroethene were associated with the highest and lowest carcinogenic risks in all 12 sample locations. Results also demonstrated that the olfactory risk in Dongjiang Lake is negligible. These data suggest that the VOCs in Dongjiang Lake may not lead great ecological and health risks for organism and human.

Exposure Studies of Different Kinds of Volatile Organic Compounds in Vapour Phase with a Narrow-gap Cell Containing CuxS Modified Carbon Microdisc Electrode

In this article, the feasibility of the CuxS modified carbon microdisc electrode was examined by exposure to four different volatile organic compounds (2-propanol, acetic acid, ethyl acetate and n-butylamine) directly in their vapour phase using cyclic voltammetry and amperometry. The performance of the modified microdisc was compared with the bare carbon microdisc (30 μm in diameter) which was involved in a narrow-gap cell. By using both methods high current increase was observed for 2-propanol with the modified electrode and its sensitivity was sufficiently higher than with the bare electrode. The modified electrode showed lower current signals in case of acetic acid and n-butylamine. The latter formed a condensation layer at the interelectrode gap. Neither the bare nor the modified electrode was sensitive to ethyl acetate.

Prediction of species concentration distribution using a rigorous turbulent mass diffusivity model for bubble column reactor simulation part II: Analogy between turbulent mass and momentum transfer in toluene emissions biodegradation process

Toluene is a kind of volatile organic compounds usually present in industrial emissions. In this work, the rigorous model for species concentration distribution prediction proposed in part I was applied in simulating the biological degradation process of toluene in a bubble column (BC) reactor. We show in the present paper that the species concentration, turbulent mass diffusivity and velocity distributions in the bubble column bioreactor can be obtained simultaneously by applying the proposed model. On the basis of the simulations, the analogy between the turbulent mass diffusivity and turbulent viscosity for the bubble column reactor was investigated. The results showed that this analogy may depend on the rate of chemical or bio-chemical reaction in the bubble columns and remain for the case with a lower reaction rate.