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1.
J Environ Manage ; 261: 109665, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32148247

RESUMO

Biotechnology has proven effective in removing a wide variety of VOCs. In this study, the effects of pH (from 3 to 7), operating temperature (20-30 °C), empty bed residence time (EBRT, 10-40 s) and transient inlet concentration (400-4000 mg m-3) on the removal performance of an airlift packing bioreactor (ALPR) was investigated. The removal efficiency (RE) and stability of the ALPR was evaluated and compared with the conventional airlift bioreactor (ALR). The results showed that under the influence of single factor variation, the ALPR showed significant higher RE and better stability than the ALR in removing dichloromethane (DCM) and toluene. Besides, a factorial design was used to analyses the interaction of multiple factors and their influence on the removal of DCM and toluene in the ALPR and ALR. It shows that pH value has the most significant influence, and plays a crucial role in maintaining high RE of DCM and toluene in both of the ALPR and ALR. Temperature has a great effect on the removal of toluene. EBRT has certain effect on the removal of DCM in the ALPR. The transient concentration of a single substrate has a significant negative effect on the RE of this substrate, while it does not significantly affect the removal of another substrate in the ALPR. However, the steep increase of DCM concentration has an adverse effect on the RE of high concentration toluene in the ALR. The overall RE and degradation capacity of both toluene and DCM by the ALPR are much higher than that of the conventional ALR.


Assuntos
Cloreto de Metileno , Tolueno , Biodegradação Ambiental , Reatores Biológicos
2.
Chemosphere ; 244: 125532, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32050334

RESUMO

Hierarchical Co3O4@MnOx material has been synthesized by in-suit growth of MnOx on the Co3O4 and applied in catalytic oxidation of volatile organic compounds (VOCs). Results revealed that T90 of acetone on the Co3O4@MnOx was 195 °C, which was 36 °C and 32 °C lower than that on the Co3O4 and MnOx/Co3O4, respectively. The universality experiments demonstrated that T90 of ethyl acetate and toluene on the Co3O4@MnOx were 200 °C and 222 °C, respectively. The above results indicated that Co3O4@MnOx catalyst presented a robust catalytic performance. Characterization results showed that high catalytic activity of the Co3O4@MnOx catalyst could be attributed to the improvement of low temperature reducibility, the enhancement of Co3+ and adsorbed oxygen species resulted from the sufficient reaction between MnO4- and Co2+ during secondary hydrothermal process. Furthermore, stability and water-resistance experiments showed the Co3O4@MnOx catalyst with high cycle and long-term stability, satisfied endurability to 5.5-10 vol. % water vapor at 210 °C.


Assuntos
Modelos Químicos , Nanofios/química , Compostos Orgânicos Voláteis/química , Adsorção , Catálise , Oxirredução , Óxidos , Oxigênio , Tolueno
3.
Inorg Chem ; 59(2): 968-971, 2020 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-31891256

RESUMO

A dithiolate/hydride bridged Fe-Ni complex, [(CN)(CO)2FeII(µ-pdt)(µ-H)NiII(CN)(PCy3)]- (2, pdt = propane-1,3-dithiolate) has been synthesized by the reaction of [(CN)2(CO)2FeII(pdt)]2- with [NiII(Cl)(H)(PCy3)2] as a synthetic analogue of the Ni-R state of the active site of the [Ni-Fe] hydrogenase. X-ray crystallography of this model complex suggests that the hydride unsymmetrically binds to Ni and Fe similar to natural [Ni-Fe] hydrogenases.


Assuntos
Monóxido de Carbono/química , Complexos de Coordenação/química , Cianetos/química , Hidrogenase/química , Tolueno/análogos & derivados , Monóxido de Carbono/metabolismo , Domínio Catalítico , Complexos de Coordenação/metabolismo , Cianetos/metabolismo , Hidrogenase/metabolismo , Ferro/química , Ferro/metabolismo , Modelos Moleculares , Conformação Molecular , Níquel/química , Níquel/metabolismo , Tolueno/química , Tolueno/metabolismo
4.
Chemosphere ; 242: 125281, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31896191

RESUMO

In this study, the potential of pulverized waste tires (PWTs), either on their own or mixed with soil (well graded sand), to act as adsorptive fill materials was evaluated by conducting laboratory tests for accessing their adsorption and geotechnical properties. PWT (0, 5, 10, 15, 25, and 100 wt%) was mixed with soil to evaluate the removal of benzene, toluene, ethylbenzene, and xylene (BTEX) components and two heavy metal ions (Pb2+ and Cu2+). Adsorption batch tests were performed to determine the equilibrium sorption capacity of each mixture. Subsequently, compaction, direct shear, and consolidation tests were performed to establish their geotechnical properties. The results showed that BTEX had the strongest affinity based on the uptake capacity by the soil-PWT mixtures. The adsorption of BTEX increased for greater PWT content, with pure PWT having the highest adsorption capacity toward BTEX removal: uptake capacities for xylene, ethylbenzene, toluene, and benzene were 526, 377, 207 and 127 µg/g sorbent, respectively. Heavy metal removal was increased by increasing the amount of PWT up to 10 wt%, and then decreased beyond this ratio. Compacted soil-PWT mixtures comprising 5-25 wt% PWT have relatively low dry unit weight, low compressibility, adequate shear capacity for many load-bearing field applications, and satisfactory adsorption of organic/inorganic contaminants, such that they could also be used as adsorptive fill materials.


Assuntos
Derivados de Benzeno/análise , Metais Pesados/análise , Poluentes do Solo/análise , Resíduos Sólidos/análise , Adsorção , Benzeno/análise , Modelos Teóricos , Eliminação de Resíduos , República da Coreia , Solo/química , Tolueno/análise , Xilenos/análise
5.
Environ Pollut ; 256: 113406, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31662251

RESUMO

Toluene is a highly volatile organic solvent present in gasoline. Exposure mainly occurs by absorption via the pulmonary tract and easily reaches the central nervous system, which causes toxic effects. Toluene toxicity has been described but not well established. The present work aimed to evaluate the effects of airborne exposure to toluene, the in vivo model Caenorhabditis elegans was assessed to determine whether nematode could be used to evaluate the effects of exposure to toluene and the possible mechanisms of toxicity of the solvent. Worms at the first or fourth larval stages were exposed to toluene for 48 or 24 h, respectively, in a laboratory-developed vapor chamber at concentrations of 450, 850, 1250 and 1800 ppm. We observed increases in worm mortality and significant developmental delays that occurred in a concentration-dependent manner. An increased incidence of apoptotic events in treated germline cells was shown, which was consistent with observed reductions in reproductive capacity. In addition, toluene promoted significant behavioural changes affecting swimming movements and radial locomotion, which were associated with changes in the fluorescence intensity and morphology of GABAergic and cholinergic neurons. We conclude that toluene exposure was toxic to C. elegans, with effects produced by the induction of apoptosis and neuronal damage.


Assuntos
Poluentes Atmosféricos/toxicidade , Caenorhabditis elegans/fisiologia , Tolueno/toxicidade , Poluentes Atmosféricos/análise , Animais , Apoptose/fisiologia , Caenorhabditis elegans/efeitos dos fármacos , Células Germinativas , Larva/efeitos dos fármacos , Locomoção/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Reprodução/efeitos dos fármacos , Tolueno/análise
6.
Bioresour Technol ; 297: 122469, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31787517

RESUMO

This work dealt with the determination of the suitability of sorption of Volatile Organic Compounds (VOCs) on biochars prepared from neem, sugarcane and bamboo feedstocks. Six different VOCs namely benzene, toluene, methyl chloride, xylene, chloroform and carbon tetrachloride were used in a laboratory-scale set-up on non-activated biochars prepared via slow pyrolysis (350-550 °C). Although all the chars showed considerable sorption but amongst them N3 (neem-based biochar) showed the maximum removal efficiency (65.5 mg g-1 for toluene). Variation in pyrolysis temperature and feedstock type showed significant change in the porosity and specific surface area of the biochar, which is favorable for VOC sorption efficiency. With higher surface area and contact time, the sorption capacity of char enhanced. However, the extent of sorption capacity of biochars differed with changing VOC type. Pseudo-Second-Order model fitted well with the results obtained from VOC sorption kinetics.


Assuntos
Compostos Orgânicos Voláteis , Adsorção , Carvão Vegetal , Tolueno
7.
J Environ Sci (China) ; 87: 39-48, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31791512

RESUMO

Carbon-silica materials with hierarchical pores consisting of micropores and mesopores were prepared by introducing nanocarbon microspheres derived from biomass sugar into silica gel channels in a hydrothermal environment. The physicochemical properties of the materials were characterized by nitrogen physical adsorption (BET), scanning electron microscopy (SEM), and thermogravimetric (TG), and the adsorption properties of various organic waste gases were investigated. The results showed that microporous carbon materials were introduced successfully into the silica gel channels, thus showing the high adsorption capacity of activated carbon in high humidity organic waste gas, and the high stability and mechanical strength of the silica gel. The dynamic adsorption behavior confirmed that the carbon-silica material had excellent adsorption capacity for different volatile organic compounds (VOCs). Furthermore, the carbon-silica material exhibited excellent desorption characteristics: adsorbed toluene was completely desorbed at 150°C, thereby showing superior regeneration characteristics. Both features were attributed to the formation of hierarchical pores.


Assuntos
Modelos Químicos , Compostos Orgânicos Voláteis/química , Adsorção , Biomassa , Carvão Vegetal , Umidade , Interações Hidrofóbicas e Hidrofílicas , Microesferas , Porosidade , Dióxido de Silício/química , Tolueno/química
8.
Environ Technol ; 41(1): 117-130, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29924682

RESUMO

Cryptomelane-type manganese oxides prepared by a solvent-free method were evaluated as catalysts for the oxidation of ethyl acetate, ethanol and toluene. The original catalyst (K-OMS-2) presented high catalytic activity for ethyl acetate and ethanol oxidation, achieving 90% conversion into CO2 around 200°C for both pollutants. Toluene was much harder to oxidize, requiring a temperature near 270°C for the same conversion. The original catalyst was mechanically treated in a ball mill at different intensities, in order to decrease the particle size for subsequent impregnation onto structured supports, as small particle sizes are usually recommended. The catalytic activity of the materials decreases with the increase in the severity of this treatment, which is related to the decrease of the surface area of the catalysts, since the other properties (phase purity, thermal stability, surface oxygen, average oxidation state and reactivity of the oxygen species) are similar among the catalysts with different ball milling treatments. For comparison, a platinum-based catalyst (1%-Pt/Al2O3) was also tested, which exhibited a high activity for toluene, but much lower activities for the two other volatile organic compounds tested. A long-term experiment, using ethanol as model pollutant, showed that the cryptomelane catalyst was stable for more than 100 h.


Assuntos
Compostos Orgânicos Voláteis , Catálise , Oxirredução , Platina , Tolueno
9.
Bioresour Technol ; 296: 122335, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31732413

RESUMO

Polyurethane (PU) sponges are popular packing material in biofilters and their smooth and hydrophobic surface often leads to an uneven distribution and detachment of biofilms. In this work, the surface of PU sponge was modified to obtain higher roughness and positive charge. The performances of two biofilters (BF1 with pristine sponge and BF2 with modified sponge) for benzene, toluene, ethylbenzene, and xylene (BTEX) removal were investigated. Total Volatile Organic Compound (TVOC) removal efficiency and CO2 increment were 61% and 804 ppm for BF2 respectively after start-up, compared with 51% and 538 ppm for BF1. Analysis on biofilms showed that the modification of PU sponge significantly improved the microbial growth, viability and adhesive strength in biofilms, reduced extracellular polymeric substance (EPS) and changed the microbial community. These results demonstrate that modified sponge can enhance biofilm formation and BTEX removal in biofilters and may applied in large-scale applications.


Assuntos
Tolueno , Xilenos , Benzeno , Derivados de Benzeno , Biodegradação Ambiental , Biofilmes , Matriz Extracelular de Substâncias Poliméricas
10.
Chemosphere ; 240: 124906, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31550587

RESUMO

Benzene homologues have significant toxic effects to aquatic organisms. In this study, the acute toxicity data of benzene, toluene, ethylbenzene and xylene (BTEX) were collected and screened, and the toxicity extrapolation model of paired BTEX was established. The results showed that except the correlation between benzene and xylene was not strong due to insufficient data, the linear correlation of the other five paired BTEX was good (p < 0.01), and R2 fitted by the four out of five paired BTEX was greater than 0.85. The cross validation showed that ethylbenzene-xylene model was optimal, and for most species (81.8%), the established five BTEX models had a prediction error of less than 10%. Also, these extrapolation models were validated by experimental results of Pseudorasbora parva. The difference between the predicted and measured values of the acute toxicity of BTEX was less than 1 fold, which indicated that the extrapolation model had high accuracy.


Assuntos
Benzeno/toxicidade , Ecotoxicologia/métodos , Tolueno/toxicidade , Poluentes Químicos da Água/toxicidade , Xilenos/toxicidade , Animais , Organismos Aquáticos , Derivados de Benzeno/toxicidade , Biodegradação Ambiental , Cyprinidae , Modelos Teóricos , Reprodutibilidade dos Testes , Testes de Toxicidade Aguda
11.
Chemosphere ; 240: 124924, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31726601

RESUMO

In this work, a 3D computational tomography (CT) of the packing material of a laboratory column biofilter is used to model airflow containing three contaminants. The degradation equations for toluene, formaldehyde and benzo[α]pyrene (BaP), were one-way coupled to the CFD model. Physical validation of the model was attained by comparing pressure drops with experimental measurement, while experimental elimination capacities for the pollutants were used to validate the biodegradation kinetics. The validated model was used to assess the existence of channeling and to predict the impact of the three-dimensional porous geometry on the mass transfer of the contaminants in the gas phase. Our results indicate that a physically meaningful simulation can be obtained using the techniques and approach presented in this work, without the need of performing experiments to obtain macroscopic parameters such as gas-phase axial and radial dispersion coefficients and porosities.


Assuntos
Poluentes Atmosféricos/química , Benzo(a)pireno/química , Formaldeído/química , Tolueno/química , Biodegradação Ambiental , Filtração/métodos , Gases , Tomografia , Tomografia Computadorizada por Raios X
12.
J Chem Phys ; 151(21): 214102, 2019 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-31822083

RESUMO

We propose an enhanced approach to the extrapolation of mean potential forces acting on atoms of solute macromolecules due to their interactions with solvent atoms in complex biochemical liquids. It improves and extends our previous extrapolation schemes by additionally including new techniques such as an exponential scaling transformation of coordinate space with weights complemented by an automatically adjusted balancing between the least square minimization of force deviations and the norm of expansion coefficients in the approximation. The expensive mean potential forces are treated in terms of the three-dimensional reference interaction site model with Kovalenko-Hirata closure molecular theory of solvation. During the dynamics, they are calculated only after every long (outer) time interval, i.e., quite rarely to reduce the computational costs. At much shorter (inner) time steps, these forces are extrapolated on the basis of their outer values. The equations of motion are then solved using a multiple time step integration within an optimized isokinetic Nosé-Hoover chain thermostat. The new approach is applied to molecular dynamics simulations of various systems consisting of solvated organic and biomolecules of different complexity. For example, we consider hydrated alanine dipeptide, asphaltene in toluene solvent, miniprotein 1L2Y, and protein G in aqueous solution. It is shown that in all these cases, the enhanced extrapolation provides much better accuracy of the solvation force approximation than the existing approaches. As a result, it can be used with much larger outer time steps, leading to a significant speedup of the simulations.


Assuntos
Simulação de Dinâmica Molecular , Hidrocarbonetos Policíclicos Aromáticos/química , Proteínas/química , Tolueno/química , Água/química , Solventes/química
13.
Environ Monit Assess ; 191(12): 762, 2019 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-31745714

RESUMO

This paper focused on VOCs and their source apportionment in urban Beijing. Our monitoring measured 52 VOCs in July 2014 and January 2015. The concentration of VOCs was in the range of 14.5~95.2 ppb in July and 2.1~93.1 ppb in January, with the top five compounds of toluene (10.7%), ethane (6.9%), ethylene (6.3%), n-butane (5.7%), and propane (5.6%) in July and ethylene (14.7%), n-butane (14.2%), ethane (9.6%), propylene (8.0%), toluene (7.9%), and benzene (6.9%) in January. The ratio of VOCs to CO reached 0.059 in July and 0.022 in January on average. These differences implied a potential seasonal difference in the VOC source contribution. Then, we conducted a source apportionment study based on 21 major VOCs and CO by using probabilistic matrix factorization (PMF) receptor model. According to the similarity between the PMF analysis profiles and the known source profiles, combustion sources, petrochemical industry sources, solvent utilization sources, and gasoline evaporation sources were identified. The correlation coefficient (R) between the PMF analysis profile and the source profile reached 0.68~0.87 in July and 0.53~0.92 in January. The better apportionment performance in July was mainly due to the use of intensive VOC observations at a 3-h resolution. When we conducted another PMF source apportionment for July based on 12-h resolved concentration input, the R values decreased to 0.47~0.73. Thus, the PMF model depends heavily on the sample number of concentration inputs, and intensive observation is more propitious. Our PMF apportionment results showed that combustion sources, petrochemical industry, solvent utilization, gasoline evaporation, and other sources contributed ambient VOCs in Beijing urban areas of 13.7 ppb, 5.1 ppb, 7.7 ppb, 12.8 ppb, and 3.3 ppb in July and 13.2 ppb, 2.0 ppb, 5.7 ppb, 6.6 ppb, and 1.0 ppb in January, respectively, on a monthly average. These apportionment results match well with the 2013 VOC emission inventory calculated by this study, but also presented significant seasonal differences in the petrochemical industry and gasoline evaporation, in which VOC emissions strongly respond to environmental temperature.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental , Compostos Orgânicos Voláteis/análise , Pequim , Benzeno/análise , China , Gasolina/análise , Indústrias , Tolueno/análise , Emissões de Veículos/análise
14.
Environ Sci Pollut Res Int ; 26(36): 36832-36844, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31745794

RESUMO

A series of Ce-doped LaMnO3 (La1-xCexMnO3) were prepared and were tested for gaseous toluene oxidation in order to investigate the effect of cerium doping in LaMnO3 on activity under photothermal conditions. It was found that the activity and CO2 yield of the catalyst can be effectively increased when x = 0.25. A group of characterization is used to characterize the morphology, composition, and physical properties of the as-prepared catalysts. Results show that the Ce-doped LaMnO3 can form coexistence of La1-xCexMnO3 and CeO2, the reaction of CeO2/La1-xCexMnO3 under photothermal conditions follows the Mars-van Krevelen redox cycle mechanism, and the prepared CeO2/La1-xCexMnO3 can form a highly efficient Z-scheme heterojunction, which can enhance the electrons transfer speed of the catalyst. Moreover, in the photothermal catalytic degradation, lattice oxygen is the most important active substance, a small amount of cerium doping can increase the lattice oxygen content of perovskite and increase the activity of the reaction.


Assuntos
Modelos Químicos , Tolueno/química , Compostos de Cálcio/química , Catálise , Cério/química , Oxirredução , Óxidos/química , Oxigênio , Titânio/química
15.
Soud Lek ; 64(2): 20-22, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31726838

RESUMO

A fatal case of abuse of solvent containing mixture of toluene and methanol is presented. Concentrations of toluene, methanol and formic acid in a femoral venous blood sample were 20.1 mg/L, 210 mg/L and 25.2 mg/L, respectively. From the autopsy findings and toxicological examination, we concluded that the cause of death was poisoning by toluene and methanol.


Assuntos
Formiatos , Metanol , Tolueno , Autopsia , Formiatos/análise , Humanos , Metanol/análise , Solventes , Transtornos Relacionados ao Uso de Substâncias , Tolueno/análise
16.
Chem Commun (Camb) ; 55(83): 12487-12490, 2019 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-31566647

RESUMO

CF2H-Pseudoprolines obtained from difluoroacetaldehyde hemiacetal and serine are stable proline surrogates. The consequence of the incorporation of the CF2H group is an important decrease of the trans to cis amide bond isomerization energy and a remarkable stabilisation of the cis conformer by an hydrogen bond.


Assuntos
Peptídeos/química , Prolina/análogos & derivados , Tiazóis/química , Tolueno/análogos & derivados , Ligações de Hidrogênio , Metilação , Conformação Molecular , Prolina/química , Estereoisomerismo , Tolueno/química
17.
Bioresour Technol ; 294: 122186, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31585341

RESUMO

Catalytic pyrolysis of biomass wastes is a promising way to produce aromatics. Based on the conventional CaO/ZSM-5 system, this study aims to improve the aromatics yields by developing an upgraded system which combined nanosized ZSM-5 with CaO from organic calcium precursors (Org-CaO/NZSM-5). The results showed that the aromatics proportion in bio-oil from pyrolysis of Jatropha de-oiled cake with Org-CaO/NZSM-5 increased to 93%. The corresponding yield of BTX (benzene, toluene and xylene) and naphthalene was around 70% which was almost twice than that with conventional CaO/ZSM-5. Org-CaO showed better thermal cracking ability and deoxygenation with more hydrocarbons intermediates and higher H/Ceff of vapors, contributing to enhanced formation of BTX over NZSM-5. NZSM-5 contained much more mesopores and acid sites on external surface, promoting higher conversion of bulky molecules into naphthalenes. Compared with peanut shell, corncob and bagasse pyrolysis, Jatropha de-oiled cake pyrolysis produced much higher aromatics with Org-CaO/NZSM-5.


Assuntos
Pirólise , Xilenos , Biomassa , Catálise , Tolueno
18.
Top Curr Chem (Cham) ; 377(5): 26, 2019 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-31529210

RESUMO

Lignin, one of the main components of lignocellulosic biomass, is the largest renewable source of aromatics on the planet and presents an extraordinary opportunity for being used in the production of bio-based products. It can be transformed for the substitution of aromatic chemical-derived petrol as BTXs. The wide range of applications that it can be obtained from BTXs building blocks makes the selective depolymerization of lignin a great scientific challenge. This review emphasizes the different strategies for the fragmentation of lignin to monomers or aromatics hydrocarbons. Thus, a by-product traditionally discarded or used for energy generation, it could be valorized into high added-value products.


Assuntos
Benzeno/química , Lignina/química , Tolueno/química , Xilenos/química , Líquidos Iônicos/química , Estrutura Molecular , Polimerização
19.
J Environ Manage ; 251: 109554, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31541847

RESUMO

In this study, performance of biotrickling filters (BTFs) inoculated with fungus Phanerochaete chrysosporium at 30 °C and 40 °C in the absence and presence of silicone oil (10% v/v) was investigated. Removal of toluene was carried out at empty bed residence time (EBRT) of 1 min and at inlet concentrations of 0.5-4.4 g m-3 and 0.5-24.7 g m-3 for one-liquid phase (OLP-BTF) and two-liquid phase BTF (TLP-BTF), respectively. In general, at 40 °C, removal efficiencies (REs) > 80% were obtained in OLP-BTF for the inlet toluene concentrations < 2.5 g m-3, and REs > 70% were obtained for concentrations < 18 g m-3 in TLP-BTF. Based on the balanced equation for biodegradation, fungal respiration produced more CO2 in OLP-BTF (1.38 mol CO2/mole toluene) in comparison to TLP-BTF (0.67 mol CO2/mole toluene). In other words, the presence of oil enhanced microbial growth due to the increase of hydrophobic substrate bioavailability. The activity of extracellular ligninolytic manganese peroxidase (MnP) enzyme produced by the fungal culture was detected in the range of 27.6-71.6 U L-1 (µmol min-1 L-1) at 40 °C in TLP-BTF, while no enzymatic activity was detected in OLP-BTF.


Assuntos
Poluentes Atmosféricos , Tolueno , Baías , Biodegradação Ambiental , Reatores Biológicos , Filtração , Fungos , Peroxidase , Peroxidases , Temperatura Ambiente
20.
Environ Pollut ; 255(Pt 1): 113100, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31542674

RESUMO

Diesel-fueled buses have been replaced by Compressed Natural Gas (CNG) to minimize the high level of emissions in urban areas. However, differences in indoor exposure levels to Benzene, Toluene, Ethylbenzene and Xylene (BTEX) in those vehicles have not been investigated so far. The primary aim of this study was to determine if passengers are exposed to different BTEX levels when using buses powered by CNG or by diesel, and further explore if indoor levels are influenced by external air quality. For this purpose, BTEX air concentrations were measured in bus cabins (CNG and diesel), parking stations and in a background urban area using passive air samplers. Results showed that BTEX concentrations inside vehicles were higher than outside, but no significant differences were found between buses powered by CNG or by diesel. In CNG vehicles, high and significant positive correlation was found between benzene and the number of journeys in the same route (rs = 0.786, p < 0.05), vehicle operating time (rs = 0.738, p < 0.05), exposure time (rs = 0.714, p < 0.05) and exposure index (rs = 0.738, p < 0.05), but this was not observed for diesel vehicles. Benzene in bus cabins was found to be significantly below reference value for human health protection. However, excepting p-xylene, all other aromatic pollutants have a mean concentration significantly above the lowest effect level (p ≤ 0.002 for all comparisons). Additionally, higher BTEX levels in cabin buses than in outdoor air suggest the presence of other emission sources in indoor cabins. These findings emphasize the need for further studies to fully characterize indoor emission sources in order to minimize the negative impact of BTEX exposure to human health.


Assuntos
Derivados de Benzeno/análise , Benzeno/análise , Gás Natural/toxicidade , Tolueno/análise , Emissões de Veículos/análise , Xilenos/análise , Poluentes Atmosféricos/análise , Poluição do Ar , Poluição do Ar em Ambientes Fechados/análise , Monitoramento Ambiental/métodos , Humanos , Veículos Automotores
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