Benzene Series Research Articles

Pollutants emission characteristics and emission reduction potential of crematoria flue gas in Beijing-Tianjin-Hebei region, China

There is a large population and high number of death in the Beijing-Tianjin-Hebei (BTH) region, therefore the amount of cremation and the incineration of sacrificial offerings is also high. Due to the loose pollution control in crematoria, the surrounding environment and human health were affected by the pollutants emitted from crematoria. To further explore the characteristics of pollution emissions from the BTH crematoria, this study carried out on-site emission monitoring of 19 cremators and 6 incinerators of sacrificial offerings in 19 crematoria in this region. The concentrations and chemical components of PM2.5 and volatile organic compounds (VOCs) and the emission levels of other gaseous pollutants from crematoria flue gas were obtained. The emission factors of air pollutants were calculated. Based on the activity level data, the emission inventory of atmospheric pollutants from the crematoria was established and its emission reduction potential was analyzed. Results showed that:(1) The average emission concentrations of TSP, CO and NOx from the crematoria in the BTH were seriously exceeding the national standard limits. Flue gas purification devices had significant effect on the removal of pollutants. (2) PM2.5/TSP=0.73 indicated that fine particles accounted for a large proportion in the flue gas of cremator; the concentration of organic matter (OC) was high and accounted for 25.3% in PM2.5. (3) The concentrations of benzene and benzene series, olefins, alkane were high in VOCs, accounting for 88.7%, which might pose health risks to exposed populations. (4) According to the emission inventory, the emissions of TSP, PM10, PM2.5 and CO in the BTH crematoria in 2016 decreased by 47.8%, 47.8%, 47.9% and 26.1% respectively compared with those for 2007. The proportion of installation purification devices for crematorium was low in the BTH region and it was common that flue gas discharged directly into atmosphere which had considerable potential of emission reduction.

Enantioselective resolutions by high‐performance liquid choromatography using chiral inorganic mesoporous silica

AbstractFour chiral hexagonal ordered mesoporous silica were synthesized by self‐assembly and templated by surface active agents prepared from d‐phenylalanine, l‐phenylglycine, l‐proline, and l‐isoleucine, with tetraethoxylsilane as the silica source and N‐trimethoxysilylpropyl‐N,N,N‐trimethylammonium chloride as the structure promoter under the induction of templates. The four generated mesoporous silica materials were used to prepare chromatographic columns to separate chiral compounds and positional isomers of benzene series with a good separation effect and a complementary effect on species separation. The experiment suggests that the four chromatographic columns have a wide range of applications and potential practical value, providing a possible direction to explore new chiral stationary phases.

Investigation of anaerobic biodegradation of phenanthrene by a sulfate-dependent Geobacter sulfurreducens strain PheS2

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous and harmful contaminants, which can be degraded aerobically. However, the persistence of PAHs in anoxic environments indicates that anaerobic biodegradation of PAHs should also be investigated. Pure-culture and biotransformation processes for anaerobic phenanthrene biodegradation with sulfate as a terminal electron acceptor remains in its infancy. In this study, we investigated anaerobic biodegradation of PAHs by PheS2, an isolated phenanthrene-utilizing sulfate-reducer, using phenanthrene as a model compound. PheS2 was phylogenetically closely related to Geobacter sulfurreducens and reduced sulfate to sulfide during anaerobic phenanthrene biodegradation. Phenanthrene biodegradation processes were detected using gas chromatography-mass spectrometry, genome, and reverse transcription quantitative PCR analyses. Carboxylation was the initial step of anaerobic phenanthrene biodegradation based upon detection of 2- and 4-phenanthroic acid, its isotopically labeled analogs when using 13C-labeled bicarbonate and fully deuterated-phenanthrene (C14D10), and genes encoding enzymes putatively involved in the biodegradation. Further, ring-system reducing and cleavage occurred, and substituted benzene series and cyclohexane derivatives were detected in downstream biotransformation metabolites. Additionally, PheS2 can degrade benzene, naphthalene, anthracene, and benz[a]anthracene, but not pyrene and benz[a]pyrene. This study describes the isolation of an anaerobic phenanthrene-degrading sulfate-reducer, the first pure-culture evidence of phenanthrene biotransformation processes with sulfate as an electron acceptor.

Leaching assessment of aerated concrete made of recycled shale gas drilling cuttings: Particular pollutants, physical performance and environmental characterization

This research aims to study how feasible it is to apply water-based drilling cuttings (WDC), Phosphogypsum (PG) and fly-ash in a coordinated way in aerated concrete, while also adopting non-autoclaved technology which can greatly save energy consumption. So the physiochemical properties, analysis of the microstructure and the environment performance of the WDC were analyzed. In the meantime, the process of hydration of all products of non-autoclaved aerated concrete including WDC were studied by using XRD, FT-IR and SEM. The findings revealed that the benzene series of WDC is all non-detected, and the heavy metals’ results of single factor index method and potential ecological environment risk were all meet the standard. The contents of heavy metals in WDC are under the level of national standard. As well as, the WDC are rich in calcium, silicon and aluminium, and the particle size is concentrated in 30 μm. This chemical and particle characteristic makes them have the basic conditions as mineral admixtures. So, the optimum mixture ratio of aerated concrete is 2.7-13.6% for WDC, 13.6-27.3% for fly-ash, 20% for cement, 11.8% for quicklime and 1.8% for phosphogypsum, and premise condition is W/S is 0.62, curing temperature and time are 80 °C and 12 h, respectively. The unit weight together with the mechanical properties of the aerated concrete that has 40% WDC (instead of 40% fly-ash) all satisfy the B06, A3.5 GB/T11968-2006 standards. Other tests were carried out to determine its environmental performance. It established that the production of aerated concrete with 40% WDC does not result in any secondary contamination. Also, based on these properties of WDC aerated concrete we propose main technology and process route of the industrial practice.

Study on Characterization and Coke Compositions of Deactivated 5 A Molecular Sieve for Adsorption Separation of Industrial Naphtha

AbstractThe deactivation causes and coke compositions of the deactivated 5 A molecular sieves (5A−E) used in the liquid phase adsorption separation process for industrial naphtha were analyzed. The results showed that 5A−E existed 14 species of C10∼C11 benzene series, naphthalene series and indans (main components of industrial corrosion inhibitor), which formed coke to block 4.4–4.9 Å micropores of 5 A−E. The coke content was ∼3.72 % and there had a strong exothermic peak at 271 °C on the surface of 5A−E. The static adsorption capacity of fresh 5 A molecular sieves for n‐hexane reduced by 24.6 % within 90 min in the isooctane/n‐hexane mixed solution containing 400 ppm industrial corrosion inhibitor. It indicated that trace corrosion inhibitor would be deposited on the surface of 5 A molecular sieves during industrial long‐term operation, resulting in slow deactivation of 5 A molecular sieves. It can provide the guidance for industrial production of liquid phase adsorption separation process of naphtha.

Association between benzene exposure, serum levels of cytokines and hematological measures in Chinese workers: A cross-sectional study

BackgroundLow benzene exposure leads to hematotoxicity, but we still lack sensitive early monitoring and early warning markers. Benzene is associated with inflammation, which is mainly mediated by cytokines network. However, until now few studies have conducted high-throughput detection of multi-cytokines to get a global view of cytokine changes and screen for markers of benzene-induced toxicity. We hypothesized that cytokine profiles mediate benzene-induced hematotoxicity. Methods228 subjects consisting of 114 low benzene exposed workers and 114 healthy controls were recruited at Research Center of Occupational Medicine, Peking University Third Hospital, Beijing. The serum concentrations of 27 cytokines were detected by cytokinomics array, urinary benzene series metabolites were measured by UPLC-MS/MS, and peripheral blood cell counts were observed by basic blood test. ResultsAmong 27 cytokines, IL-9 and MIP1-α were significantly lower, but IL-4, IL-10, IL-15, MCP-1, TNF-α and VEGF were significantly higher in benzene exposure group than controls. Urinary benzene metabolite S-phenylmercapturic acid (S-PMA) was significantly higher in benzene exposure group and had a negative linear relationship with WBC count. S-PMA was only significantly associated with IL-9, meanwhile IL-9, IL-15 and VEGF had a positive linear relationship with WBC count. The bootstrapping mediation models showed that the effect of S-PMA on WBC count was partially explained by IL-9 for 10.11%. ConclusionThis study suggests that exposure to benzene was associated with alternation of blood cell count and cytokine profiles in workers exposed to low levels of benzene, especially decreases of WBC count and IL-9. We also found IL-9 partially mediated the effect of low benzene exposure on WBC count, which may be a potential and promising early monitoring and early warning marker of benzene hematotoxicity.

Characteristics of Volatile Organic Compounds in Wood Coatings and Automotive Coatings in China

Presently, there are a few studies on the measurement of industrial organic solvents in China. To determine the content and species of volatile organic compounds (VOCs) in industrial organic solvents and to provide the emission factors of organic solvents, the Chinese wood and automotive coatings, which accounted for the largest proportion of production in the world, were investigated. Coating samples were obtained by sampling from companies and buying from markets, and were measured in accordance with the domestic standard testing methods for coatings. The content and composition spectrum of VOCs in the coatings were determined, and the ozone formation potential (OFP) was then calculated. The results showed that for wood coatings, the average content of the VOCs in solvent-based, water-based, and ultra-violet (UV) coatings were 37.28%, 9.88%, and 18.02%, respectively. For automotive coatings, the average content of the VOCs in water-based original equipment manufacturer (OEM) coating, solvent-based OEM coating, water-based refinishing coating, and solvent-based refinishing coating were 15.06%, 59.90%, 11.79%, and 54.50%, respectively. The content of the VOCs in different types of coatings varied substantially. The main components and OFP contributors were alcohols and ethers for water-based coatings, benzene series and esters for solvent-based coatings, and esters, alcohols, and ethers for UV coatings. The average value of the coating samples could meet the current mandatory national standards, but 12% of the solvent-based wood coating samples and 42% of the solvent-based OEM coating samples did not meet the standards. In addition, except for the benzene series of the water-based wood coatings, the contents of harmful substances in other coating samples were up to the standards.

Source Profiles of Industrial Emission-Based VOCs in Chengdu

The volatile organic compound (VOC) emission characteristics of various production procedures were analyzed through GC-MS after the emissions of typical enterprises such as automobile manufacturing, petrochemical, and other industries had been sampled with SUMMA canisters. Each production procedure in the automobile manufacturing and petrochemical industries was considered. The results showed that each automobile manufacturing procedure had its own dominant species, and alkanes (32%) and aromatics (35%) were the main emission species of coating spraying. The emission characteristics of furniture manufacturing were highly correlated with the raw materials, and the VOC emission species were mainly composed of aromatics (50%) and oxygenated VOCs (OVOCs) (38%). As for the petrochemical industry, VOC concentrations in various process plant areas ranged from 49 μg·m-3 to 1387 μg·m-3. As the main products of the refining area were C5-C9 gasoline and benzene series, whereas comparatively more solvents were used in the chemical area, which would generate alkene products, VOC concentrations greatly differed in the various process plant areas. In terms of electronic manufacturing, OVOCs were the main emission species, accounting for more than 50% of total VOCs. Alkanes and OVOCs were the main contributors to VOC emissions in shoemaking, accounting for 52% and 36% on average, respectively, which was strongly related to the species of the used solvents. The VOC emission species of automobile manufacturing were quite different, predominantly including n-dodecane and 2-butanone. The emission species of furniture manufacturing mainly included styrene, ethyl acetate, m/p-xylene, etc., which are typical species of coatings and diluents. As for the differences in the emission species of process plant areas in the petrochemical industry, styrene was the main species in the refining area, 1,3-butadiene in the chemical area, C3-C5 alkanes in the storage area, and C6-C8 alkanes in the wastewater treatment area. The main emission species of electronic manufacturing were ethanol, acetone, and other aldehyde ketone species. The emission species of shoemaking enterprises are mainly C5 and C6 alkanes. According to the results of ozone formation potential (OFP), alkenes and aromatics were the main VOC emission species that contribute significantly to the OFP in the automobile manufacturing and petrochemical industries, with relatively high pollution source reaction activity. The results showed that the emission ratio (17%-96%) and OFP contributions of OVOCs were significant in various industries. Therefore, for VOC emission control, in addition to focusing on the control of aromatics and alkenes, attention should also be paid to OVOCs.

Emission Characteristics and Risk Assessment of Volatile Organic Compounds from Typical Factories in Zhengzhou

To understand the characteristics and potential hazards of volatile organic compounds (VOCs) emitted from different industrial factories in Zhengzhou, several representative factories have been selected for sample collection using canisters; the samples were subsequently analyzed by GC-MS/FID system, from which the composition and risk of VOCs are discussed in this study. It was found that OVOCs, especially ethyl acetate and isopropanol, were the most important species originating from printing factories, which accounted for more than 93.1% of total VOCs. The major components related to manufacturing industries, including automobile, furniture, and coating, were aromatics, mainly m/p-xylene, o-xylene, and ethylbenzene, which contributed 33.5%-90.0% to VOCs. Halogenated hydrocarbons made the largest contribution (52.3%) to VOCs in the food processing industry. The main components of VOCs were halogenoalkanes (25.5%) and alkanes (28.8%) in rubber factories. As for graphite carbon factories, the main components of VOCs were aromatics (28.5%) and alkanes (24.1%). Compared with previous studies, the VOC emission characteristics of factories involving solvent usage in Zhengzhou are consistent with those in other cities, but the compositional information of VOCs varies across different factories, even within the same industry, due to the different production processes and raw materials used. Risk assessment showed that the concentration of VOCs emitted from solvent factories are positively correlated with ozone formation potential (OFP) and the hazard index (HI). Specifically, benzene, toluene, ethylbenzene, xylene, and other C6-C8 aromatic hydrocarbons contributed significantly to OFP and HI. The HI values were 1.18 and 2.74 in automobile manufacturing factory NO.3 and wooden furniture factory NO.5, respectively, which were higher than the limits stated by EPA regulations because of the different production processes and raw materials, and the VOCs of the factories were mainly composed of aromatics; in particular, C6-C9 benzene series contributed significantly to HI and OFP. Therefore, it is necessary to control VOCs originating from industries involving solvent usage.

Interactive tools to assist convenient group-type identification and comparison of low-temperature coal tar using GC × GC–MS

Coal tar is considered a valuable product obtained from coal pyrolysis. An accurate and convenient analytical study on its composition would be of great significance for its further processing and utilization. This work focused on the group-type identification and comparison of low-temperature coal tar by using comprehensive two-dimensional gas chromatography-mass spectrometry (GC × GC–MS). In this work, three low-temperature coal tar samples, diluted in dichloromethane, were analyzed by GC × GC–MS. It was observed that aliphatic hydrocarbons, benzene series, phenolic compounds, benzenediol compounds, naphthol compounds, naphthalene series, anthracene series, indene series and other different types of compounds in coal tar exhibited zonal distribution in the two-dimensional contour plot. The classification of different groups can be achieved by construction of spatial polygons. The classification results showed good reliability confirmed by manually identifying each compound contained in each group. The application of computer language for identifying compounds (CLIC) based on mass fragment characteristics and retention time assisted greatly in the identification of different chemical groups. Five major chemical groups including aliphatics, aromatics, oxygen-containing compounds, nitrogen-containing compounds and sulfur-containing compounds were retrieved from the two-dimensional contour plot by automated pattern recognition using CLIC expressions. The relative content of different chemical groups between a series of contour plots can be conveniently compared by comprehensive implementation of CLIC expressions and an interactive feature template matching function.

Synchronous degradation of phenol and aniline by Rhodococcus sp.strain PB-1entrapped in sodium alginate-bamboo charcoal-chitosan beads

ABSTRACT The biodegradation of benzene series compounds is a difficult problem in environment pollution control, which is attributed to the deficiency of high efficiency bacteria and suitable embedding materials. In this study, the immobilized cells Rhodococcussp. strain PB-1 was used to synchronously biodegrade phenol and aniline by entrapped in sodium alginate (SA)-bamboo charcoal (BC)-chitosan acetate (CA) beads. The free cells of the strain PB-1 could completely degrade 1500 mg/L phenol or 800 mg/L aniline within 48 h, while the degradation rate of 2000 mg/L phenol and 1500 mg/L aniline was 35.76% and 68.06% at 72 h, respectively. The ortho-cleavage pathway was used to degrade phenol and aniline by strain PB-1. However, after entrapped with SA-BC-CA beads,the removal rate of 2000 mg/L phenol was 100% at 108 h, 1500 mg/L aniline was 100% at 62 h and 2000–3000 mg/L total toxic compounds was over 95% at 120 h. These beads could be used four times and were more effective than SA or SA-BC beads. The SA-BC-CA beads could remarkably improve the stability and degradation efficiency of strain PB-1, and thus provide a potential application in the removal of phenol and aniline in wastewater.

Superhydrophobic Hierarchical Porous Divinylbenzene Polymer for BTEX Sensing and Toluene/Water Selective Detection

As shown in the Fig.1, this work reports a superhydrophobic divinylbenzene polymer with hierarchical porous structure as sensing material to modify the quartz crystal microbalance (QCM) to detect benzene, toluene, ethylbenzene, and xylene (BTEX) vapor. Notably, sensing results toward toluene vapor in different relative humidities indicates that this superhydrophobic polymer has favorable toluene/water selective detection performance. Besides, the limit of detection toward toluene is lower than 1 ppm.IntroductionAs typical hazardous chemicals, benzene series, especially BTEX, are easily dispersed in the air because of their extremely easy volatile nature. BTEX can paralyze the central nervous system of humans, causing neurasthenia, liver disease, and even cancer. Therefore, using gas sensor for real-time detection of BTEX is necessary.Compared with other sensors, QCM sensor has the advantages of low cost and working at room temperature. By modifying sensitive materials on the surface of QCM, the target gas can be adsorbed and the surface quality of QCM changes. This change can be further transformed into frequency shift by Sauerbrey equation, and recorded by computer. Based on QCM platform, some benzene sensors have been reported. For example, Kumar et al. used tetra-tert-butyl copper phthalocyanine to realize the sensing of BTEX. The response to 500 ppm of toluene can reach 60 Hz. But none of these reports discussed the effect of humidity on the sensor response. Our research group detected the BTEX vapor via using superhydrophobic polyoctadecylsiloxane (PODS) based on QCM. Besides, PODS can stably detect toluene vapor under different relative humidities. However, when the concentration of toluene is 20 ppm, the response value is only about 7 Hz. It is indicating that the detection limit of PODS to toluene cannot be less than 20 ppm. Figure 1

Flammability limits of benzene, toluene, xylenes from 373 K to 473 K and flame-retardant effect of steam on benzene series

Typical benzene series (benzene, toluene, xylenes), while having important applications in chemical industry, are also threatening industrial safety and daily life due to high flammability. In this work, we measured the flammability limits of benzene, toluene, xylenes by ASHRAE method based on E681-09 at elevated temperatures (373 K, 423 K and 473 K). As the temperature increased, the flammable concentration ranges of benzene series expanded. On the basis of flammability limits experimental results, the flame-retardant effect of steam (H2O) on benzene, toluene, o-xylene, m-xylene, and p-xylene were investigated at 423 K separately. These experimental data were correlated with the extended Le Chatelier’s law and compared with theoretical estimations based on adiabatic flame temperature (AFT) method. The experimental results were completely reproduced by the extended Le Chatelier’s law. The lower and upper flammability limits (LFLs and UFLs) of benzene/toluene + H2O agreed well with the estimations, and the upper flammability limits of xylenes + H2O were within acceptable absolute deviation range. The average absolute deviations (AADs) of the lower and upper flammability limits for benzene series + steam between experimental results and optimized estimations were 0.07 % and 0.38 % separately. Moreover, flame-retardant effect of other diluents (N2 and CO2) on benzene series were calculated theoretically, and all the critical flammable ratios (CFRs) were close to 1. The results showed that the flame retardancy on benzene series need to be considered seriously rather than using common diluents.

Characteristics of organic matter sources from Guadiana Estuary salt marsh sediments (SW Iberian Peninsula)

Estuaries are dynamic interfaces between land, rivers and the ocean that play major roles in the global carbon cycle. These coastal wetlands store huge amounts of organic carbon (OC), commonly known as “blue carbon” and excellent places to study C cycling. The Guadiana river estuary is among the most important tidal salt marshes in the South - Iberian coastal margin. Here, a detailed organic geochemical study is described that includes the identification of sedimentary OM composition at a molecular and isotopic level. Total organic carbon content (TOC) of core sediments ranged from 0.39 to 2.23% and stable carbon isotope composition (δ13C) also showed a wide range between −22.4 and −27.0‰. A13C depletion trend observed from the surface to bottom in the core sediments profiles, reflects loss of labile biogenic 13C enriched compounds i.e. polysaccharides and a selective preservation of more depleted compounds with depth i.e. lignin and lipids in the core sediments. Series of n-alkanes were found in the range from C10 to C31. Carbon preference index ratio (CPI) calculated for long-chain n-alkanes (C24–C31) that ranged between 1.17 and 1.94 reflecting diverse OM inputs to the sediments. A study of the lignin-derived phenolic composition pointed to a recalcitrant OM derived from both gymnosperm and angiosperm plants. Moreover, high abundance of vinyl phenol and vinyl guaiacol points to a dominant contribution of lignins from grasses and aquatic macrophytes to the sediments. A well-resolved series of long-chain linear alkyl benzenes (LABs from C4 to C22) were recorded in all core sediment samples indicating direct discharge of untreated domestic and/or industrial effluents to the estuary. Polycyclic aromatic hydrocarbons (PAHs) with more than 3 rings reflects the pyrogenic origin of a portion of the sedimentary OM. This study highlights the importance of different OM sources to the lower Guadiana estuarine sediments and contributes to a better knowledge about its origin, dynamics and fate.

Solvent-Free and Liquid-Phase Iodination of Thiophene Derivatives with Potassium Dichloroiodate Monohydrate

Iodination of a series of benzene and thiophene derivatives by potassium dichloroiodate monohydrate was studied with and without a solvent. The liquid substrates tend to be more reactive in water while the solid substrates afford better yields in dichloromethane or under the solvent-free conditions. The 2-substituted thiophenes show good to excellent yields whereas the yield for 3-substituted and 3,4- or 2,4-disubstituted thiophenes and benzene derivatives are significantly lower. The mechanochemical reaction of 5-carbaldehyde-2,2′-bithiophene shows excellent yields, while 2,2′-bithiophene gives practical yields only in dichloromethane. In the case of thiophene and N-acetyl-p-toluidine, electrophilic iodination is accompanied by a small extent of chlorination.

Effect of n-hexane extraction on the formation of light aromatics from coal pyrolysis and catalytic upgrading

In order to investigate the effect of aliphatics in coal on the formation of light aromatics (benzene, toluene, ethylbenzene, xylene and naphthalene, called BTEXN) from coal pyrolysis and catalytic upgrading using on-line Py-GC/MS, n-hexane was used to extract Shengli lignite (SL) and Pingshuo bituminous coal (PS). The extracts of the two coals (SLE and PSE) were analyzed by GC × GC-MS. Results show that aliphatics account for 85% of SLE and 68% of PSE. It brings about that the total yields of BTEXN from SL residue and PS residue pyrolysis are decreased by 29% and 18% compared with raw coals. This is because the aliphatics could provide small-molecule free radicals to stabilize the light aromatic cracking fragments and promote the formation of BTEXN during pyrolysis. The amounts of the alkyl benzene series, phenols, and polycyclic aromatic hydrocarbons from pyrolysis gaseous tar are significantly increased after extraction and they will undergo catalytic cracking to form BTEXN over USY zeolite, resulting in that the total yield of BTEXN from residue is almost same as that from raw coal during catalytic upgrading.

过硫酸盐对化工污染场地苯系物修复效果研究

过硫酸盐对化工污染场地苯系物修复效果研究

Tube-type passive sampling of cyclic volatile methyl siloxanes (cVMSs) and benzene series simultaneously in indoor air: uptake rate determination and field application.

Cyclic volatile methyl siloxanes (cVMSs) and benzene series compounds have attracted increasing attention because they are associated with various adverse health effects. In this study, we developed and validated a novel passive air sampling method (PAS), using Tenax-TA as the sorbent, to measure the concentrations of cVMSs (D4, D5, and D6) and benzene series compounds simultaneously in indoor air. The uptake rates (R), which were calibrated side-by-side by an active air sampling method (Tenax-TA-AAS), ranged from 0.10 to 0.56 mL min-1 depending on chemicals, and the R of the TD tube with Tenax-TA was controlled by the sampler material-side and not the air-side. The passive sampling efficiency (PSE) of styrene and m,p-xylene was close to 1. Based on Pearson correlation analysis, a negative correlation was found between the molecular weight of compounds and their uptake rates. Furthermore, the calibrated Tenax-TA-PAS method was used to quantify cVMSs and benzene series compounds in a living room and an office environment in the urban area of Dalian, China. The concentrations of toluene were the highest in both the living room (10.4 μg m-3) and office (7.02 μg m-3) among the target compounds.

Distribution Characteristics of Volatile Organic Compounds and Contribution to Ozone Formation in a Coking Wastewater Treatment Plant.

Ozone pollution, which can be caused by photochemical reactions, has become a serious problem. The ozone formation potential (OFP) is used to describe the photochemical reactivity. Volatile organic compounds (VOCs) are main precursors of ozone formation, and wastewater treatment plants (WWTPs) are important sources of VOCs. Therefore, it is necessary to study the concentration level and OFP of VOCs from WWTPs. In this work, a coking WWTP with anaerobic-oxic-oxic (A/O/O) processes in Shaoguan city, Guangdong province, China, was selected to investigate the characteristics of VOCs at wastewater treatment areas and office areas. The OFP of VOCs was estimated by the maximum incremental reactivity (MIR) coefficient method. Results showed that 17 VOCs were detected, and the total concentration of VOCs was the highest at the raw water tank (857.86 μg m−3). The benzene series accounted for 69.0%–86.9% and was the main component of VOCs in the WWTP. Based on OFP data, the top six VOCs contributing most to the OFP were m-xylene, toluene, p-xylene, o-xylene, styrene, and benzene. This study provides field data and information on the environmental risk of VOCs for coking companies and environmental departments. We found that the priority control sources of VOCs were wastewater treatment units because of their larger OFP contributions.

Load characteristics and inhalation risk assessment of benzene series (BTEX) pollutant in indoor air of Ghalyan and/ or cigarette cafes compared to smoking-free cafes

ABSTRACT To determine the concentration of benzene series (BTEX) compounds, 33 samples were collected from indoor air of Ghalyan cafés (GHC), cigarette cafés (CC) and smoking-free cafés (SFC) in Bushehr city, Iran, and analyzed using gas-chromatography - flame ionization detector (GC-FID). The results of this study indicated that the mean±SD values of ΣBTEX in GHC, CC and SFC cafés were 19.46 ± 6.07, 11.34 ± 5.21 and 2.26 ± 0.76 mg/m3, respectively. The mean concentration of BTEX in the cafés with fruit-flavored tobacco was significantly higher than those in traditional cafés (p < 0.05). According to path analysis, the number of active waterpipe heads had the maximum impact on the production of pollutants inside the cafés. The results also indicated that the risk of exposure to BTEX in smoking cafés in Bushehr was very high; it can develop serious carcinogenic and noncarcinogenic risks.