Aromatic Hydrocarbon Components Research Articles

Characterization of carbonaceous components and PAHs on ultrafine particles in Phnom Penh, Cambodia.

This study investigated seasonal fluctuations in particulate matter (PM) concentrations, including carbon and polycyclic aromatic hydrocarbon (PAH) components, in Phnom Penh, Cambodia, focusing on ultrafine particles (UFPs or ≤ 100nm). UFP levels were notably higher during the dry season, averaging 23.73 ± 3.7µg/m3 compared to 19.64 ± 3.4µg/m3 in the wet season, attributed to increased emissions from vehicles and agricultural burning. In contrast, lower concentrations during the wet season were due to scavenging effect of rain. When compared to other Southeast Asian cities, UFP levels in Phnom Penh were significantly higher during the dry season, surpassing those in cities like Bangkok and Kuala Lumpur. Seasonal variations in carbonaceous components showed higher elemental carbon (EC) and total carbon (TC) during the dry season, with EC/TC ratios suggesting substantial influence from vehicular emissions and biomass burning. PAH analysis revealed seasonal disparities, with higher concentrations of benzo[b]fluoranthene (BbF) and benzo[k]fluoranthene (BkF) during the wet season, whereas fluoranthene (Flu) and pyrene (Pyr) were consistently present, indicating diverse PAH sources. The Flu/(Flu + Pyr) ratios, indicative of biomass burning, were higher in the dry season. Correlations between PAHs and carbon components confirmed combustion as a significant source of PAHs, aligning with global trends. This emphasizes the need to address distinct PM sources during various season in Phnom Penh.

Automation of the Formation of a Mathematical Formulation of Kinetics for Multistage Chemical Reactions and Numerical Solution to a Direct Problem

Introduction. The basis for research, analysis and mathematical optimization of any chemical process is an adequate mathematical model that takes into account the kinetics of the object. Kinetic analysis is a challenge in chemical technology, since it allows for optimizing synthesis processes and predicting their efficiency. Numerous chemical processes involve several stage reactions. For successful design and optimization, a mathematical model that describes each stage is needed. Creating such a model manually can be time-consuming and costly, since it requires processing a large amount of information. The modern level of automation makes it possible to accelerate the obtaining of a mathematical formulation of the kinetics of multistage reactions. In this case, working with data is greatly simplified, and the probability of making mistakes is reduced. The resulting mathematical model can be applied for further analysis and optimization of the process. The paper considers the industrial reaction of catalytic reforming of gasoline, which occupies an important place in the modern scheme of oil refining, since it is a source of high-octane components of commercial gasolines and individual aromatic hydrocarbons. This process is characterized by the participation of a large number (up to 300) of various hydrocarbons, a change in the number of moles, and non-isothermality in it. Mathematical modeling of such processes involves detailing the stages to the required level. The detailing of up to 173 stages is considered. In this setting, automation of the formation of a mathematical formulation of kinetics for catalytic reforming of gasoline has not been carried out before. Therefore, the presented work aimed at implementing effective numerical methods and algorithms for automating the building of a mathematical model taking into account kinetics, thermodynamics, and changes in the number of moles.Materials and Methods. The mathematical formulation of the kinetics of multistage reactions was developed on the basis of the mass action law. The kinetic parameters values were taken from literary sources. The direct kinetics problem was solved using algorithms: the Gear method, the Runge-Kutta method of the 4th order, and the scipy.odeint() method of the Python language. The automation concept was implemented using the IDEF0 methodology. The software was written in the Python programming language.Results. A new software was created to automate the process of forming a mathematical model, taking into account the kinetics, thermodynamics, and the volume of the reaction mixture. The program results were presented by the example of catalytic reforming of gasoline. The model implemented the possibility of taking into account the intermediate heating of the mixture in the reactor cascade. Numerical values of temperature changes corresponding to industrial data were obtained.Discussion and Conclusion. The results obtained through modeling chemical transformations in the cascade of gasoline catalytic reforming reactors confirmed the exothermic nature of the reaction. The developed software product provides displaying changes in the concentrations of reactants, as well as temperature variations in the reactor, and it can be used in scientific research organizations for the analysis of multistage catalytic processes. The results of the reaction kinetics modeling will be used in the subsequent optimization of the process conditions in production.

Soil Washing to Eliminate Polycyclic Aromatic Hydrocarbons from Petroleum Contaminated Soil - Temperature Effect

This study’s goals were to identify the components of polycyclic aromatic hydrocarbons (PAHs) in soil samples polluted with petroleum and to ascertain how temperature affected the removal of PAHs pollutants from petroleum-contaminated soil. The concentration of contaminants in the soil samples decreased from 46.22-12.07 ppm to 77.01-30.06 ppm at a temperature increase of 20–160°C, as shown by the results of this study, which are also supported by the percentage removal efficiencies of 22.22–79.69% and 32.90–73.81% for samples M and S, respectively. It was further discovered that 160℃ was the ideal temperature range for soil washing to eliminate the pollutants. High removal efficiency values demonstrated the efficacy of the soil washing approach in removing pollutants with high PAH concentrations. This information can help in the creation of more successful and affordable soil remediation techniques.

Characteristics of VOCs and Assessment of Emission Reduction Effect During the Epidemic Lockdown Period in Shenzhen Urban Area

To prevent disease spreading during the COVID-19 epidemic, Shenzhen adopted lockdown measures in March of 2022. This provided an opportunity to study the response of changes in anthropogenic volatile organic compounds (AVOCs) in Shenzhen to emission reduction and to evaluate the effectiveness of current emission reduction measures. This study analyzed the variety of AVOCs before, during, and after the epidemic lockdown based on the online observation data of pollutants at Lianhua Station in Shenzhen from March 7, 2022 to March 27, 2022. Additionally, the sensitivity of ozone formation and the assessment of the reduction effect of precursors was conducted by an observation based model(OBM). The results showed that:affected by regional influences and the interference of meteorological conditions, the average value of AVOCs in Shenzhen urban areas did not drop significantly during the lockdown period compared to that before the lockdown. However, the peak of AVOCs at the morning peak time under the influence of "sea and land wind" during the epidemic lockdown period dropped by 46% on average compared with that during the non-lockdown period, and the aromatic hydrocarbon component dropped the most by 59%. Additionally, under the influence of continuous easterly wind, or during the accumulation and increase of AVOCs affected by regional transmission, aromatic components also decreased by an average of 25% and 21%, respectively. During the lockdown period of the epidemic in Shenzhen, the O3 formation in urban areas was still AVOCs-limited. Increasing the emission reduction ratio of AVOCs was the most effective measure to reduce O3 in the short term. In order to ensure the effectiveness of emission reduction, it was recommended that the coordinated emission reduction ratio of AVOCs and NOx should be greater than 1:2. It was only possible to enter the downward channel of O3 if the deep emission reduction was more than 60%. This study revealed that the emission reduction of AVOCs during the morning traffic peak during the epidemic lockdown period was conducive to inhibiting the formation of O3, whereas the control of NOx would promote it. Strengthening the control of local aromatic hydrocarbon components during the regional impact process could also significantly reduce O3 production. At this stage, Shenzhen should strengthen the management and control of industrial solvents, especially to reduce the aromatic hydrocarbon components in the solvent source that have a greater impact on the generation of O3. Further, Shenzhen should continue to promote the reform of the energy structure of motor vehicles to reduce the emission of VOCs in fuel combustion.

Transboundary haze from peatland fires and local source-derived PM2.5 in Southern Thailand

This study characterizes impacts on PM2.5 of transboundary haze from peatland fires in Indonesia and local emission sources during 2019–2020 to a large and densely populated city, Hat Yai in southern Thailand. Organic carbon (OC), elemental carbon (EC), water soluble organic carbon (WSOC), water soluble ions (WSI: Cl−, NO3−, SO42− and NH4+), element tracers (K, Na, Mg and Ca), heavy metals (Cr, Co, Pb, Cd, Ni, Mn) and As, and 16 polycyclic aromatic hydrocarbon (PAHs) components from PM2.5 samples (n = 18) were measured to identify local and regional emission sources using a chemical mass balance (CMB) model. We used a combination of air mass backward trajectories and CMB source apportionment to identify PM2.5 sources. An increase of PM2.5 and chemical component concentrations, during the transboundary haze period, were clearly influenced by aerosols from open biomass burning in Indonesia: PAH concentrations were 2 times higher and OC concentrations, 5 times higher. Secondary organic carbons were predominant during transboundary haze periods, accounting for 52–58% of total OC, indicating higher secondary organic aerosol formation. High K levels demonstrated that the dominant source during this period was biomass burning. Whereas a high level of Ca in the background air came from urban road dust, as well as local biomass burning. Moreover, the increased concentration of SO42−, NH4+ and NO3− during the wet season, as well as transboundary haze periods, was mainly derived the secondary inorganic aerosol formation. Effect on PM2.5 concentration from a volcanic eruption near the air mass trajectory during the sampling period was minimal. However, it may have contributed slightly to an increase of SO42− concentration in PM2.5. Sources of PM2.5 in Hat Yai were clearly influenced by local emission sources, e.g. diesel combustion and biomass burning (rubber wood and rice straw), transboundary haze and also secondary organic and inorganic aerosols.

Heavy Metal Contamination Index, Metal Index and Polycyclic Aromatic Hydrocarbon Content of Ochani River in Ogoni, Rivers State, Nigeria

The Heavy metal Pollution Index (HPI), Metal Index (MI) and the Polycyclic Aromatic Hydrocarbon (PAH) contents of crude oil-polluted Ochani River in Ejamah-Ebubu community were investigated using physicochemical properties, Heavy Metal Analytic Method (AAS), GC-MS method and heavy metal pollution model. The results showed that Ochani River sampling station 2 (ORPS 2) had highest values of temperature, conductivity, turbidity, total solid (TS), total dissolved solid (TDS), Total Suspended Solid (TSS), Dissolved Oxygen (DO), Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD) and nitrates with values as (32oC, 260 µScm-1, 42NTU, 460 mg/L, 526 mg/L, 400 mg/L, 15 mg/L, 10 mg/L, 25 mg/L and 7.5 mg/L respectively) compared to Ochani River sampling station 1 (ORPS 1) with values as (30oC, 200 µScm-1, 38NTU, 400 mg/L, 500 mg/L, 380 mg/L, 13 mg/L, 9.0 mg/L, 22 mg/L and 6.8mg/L respectively). However, these values of ORPS 1and 2 were higher than the unpolluted water sample (UWS) and WHO standard limits. Heavy metals obtained in Ochani River were rankedas Fe > Cu >Pb> Zn > Cr > Cd >As. The values obtained from crude oil polluted water samples were highest when compared with the values obtained of the UWS and WHO standard limit. The heavy metal pollution index of Ochani River was calculated as 402.32 mg/L which was higher compared with the critical pollution index value of 100. The metal index obtained was 49.88mg/L showing that the water quality classified to be seriously polluted. The Polycyclic Aromatic Hydrocarbon (PAH) components present in Ochani River include fluorene, naphthalene, dibenzyl(a,h)anthracene, benzo(k)fluoranthene and benzo(a)pyrene. However, these values of PAH components obtained were highest in ORPS 2 compared to ORPS 1. No PAH content was detected in UWS. However, the values of PAH obtained in both ORPS 1 and 2 were higher compared with WHO standard limit. In conclusion, Ochani River which is an important river used for irrigation and domestic activities by the populace in that community, is highly polluted with heavy metals and carcinogenic PAHs. We therefore recommend that Ochani River is unsafe for drinking, domestic and agricultural activities of the community where it is sited.

Variety of the Composition and Sources of VOCs During the Spring Festival and Epidemic Prevention in the Pearl River Delta

Volatile organic compounds (VOCs) are the key precursors of the ozone (O3) formation processes in the troposphere and are important control objects for the coordinated governance of O3 and PM2.5. The Spring Festival of 2020 was affected by the novel coronavirus (COVID-19) pneumonia epidemic:companies stopped work and production, and traffic was restricted, providing scientific experimentation opportunities for pollutant emission reduction research. This study analyzed the variety of the composition, chemical reaction activity, and sources of VOCs in the Pearl River Delta during the Spring Festival and the epidemic control period, using real-time online monitoring data of VOCs obtained at four sites(Guangzhou, Dongguan, Zhongshan, and Duanfen)in the Pearl River Delta from January 1, 2020 to February 29, 2020. The results showed that during the Spring Festival and the epidemic control period, the average of φ (VOCs) in the Pearl River Delta was 15.89×10-9, and the maximum hourly average concentration was 45.43×10-9, values that were 44% and 60% lower, respectively, than those before the Spring Festival holiday. Among the VOCs component concentration decreases, the aromatic hydrocarbon component decreased the most, and the decrease in the urban area of the Pearl River Delta (74%) was significantly greater than that in the suburban area (56%). As a result, the contribution rate of aromatic hydrocarbons to the total VOCs was reduced to less than 10%. The analysis of the·OH reaction activity of VOCs(L·OH)and ozone formation potential(OFP)showed that the L·OH and OFP of VOCs decreased significantly in the Pearl River Delta during the Spring Festival and the epidemic control period. Compared with those before the Spring Festival holiday, the total L·OH and total OFP decreased by an average of 60% and 63% in the urban area of the Pearl River Delta, respectively. Additionally, the atmospheric oxidation had also been significantly reduced, which showed a 28% decrease in ρ(Ox). The ratio of toluene/benzene showed that the influence of industrial sources had almost disappeared during the Spring Festival and the epidemic control period, and the total points of the representative components of industrial-related solvent-use sources such as toluene, ethylbenzene, and m/p-xylene dropped by 72% to 91%. The results of this study suggest that solvent-use sources and vehicle exhaust emission sources are the current sources of VOCs that need to be paid attention to in the prevention and control of O3 pollution in the Pearl River Delta region, and the impact of petrochemical sources cannot be ignored in the work of further reducing the background concentration of O3.

Regulating aromatic hydrocarbon components from catalytic pyrolysis of corn cob lignin with a tailored HZSM-5@Al-SBA-15 hierarchical zeolite

Catalytic pyrolysis of corn cob lignin were preformed using a tailored HZSM-5 @Al-SBA-15 hierarchical zeolite for the production of value-added aromatic hydrocarbon. Resulted showed that the highly ordered two-dimensional p6mm mesoporous shell could uniformly form on the surface of HZSM-5 core phase. The porosity and acidity of the HZSM-5 @Al-SBA-15 could be tailored by adjusting the TEOS/HZSM-5 mass ratio in the synthesis process. The aromatic hydrocarbon components regulated due to pre-cracking and enhanced diffusion via the mesoporous shell, as well as the retained shape-selectivity of the HZSM-5 core. Herein, the relative content of MAHs reached 45.02% with fewer poly-aromatic hydrocarbons (PAHs) of 25.91% when the TEOS/HZSM-5 mass ratio of 1.0. However, the length of the diffusion path had a certain impact on the anti-coking behavior. The catalytic stability of the hierarchical zeolites was also improved, with less coke formation than HZSM-5 alone. This work demonstrates that using a tailored hierarchical zeolite to regulate aromatic hydrocarbon components is feasible, and provide a reference for the practical application of agricultural crop wastes.

Personal exposure to electrophilic compounds of fine particulate matter and the inflammatory response: The role of atmospheric transformation

Atmospheric oxidation can produce electrophilic compounds, altering the health effects induced by fine particulate matter (PM2.5); however, little is known about these electrophilic compounds or their health effects. Using electron capture negative ionization, we systematically detected 301 electrophilic compounds from personal PM2.5 samples in a panel study in urban Beijing. Most were oxygen-containing compounds with 3–17 double bond equivalents (DBE), suggesting the dominance of oxidized aromatic structures. Over 64% of the species, mostly outdoor-originated, were associated with inflammatory cytokines in both exhaled breath condensate and serum. Primary components of polycyclic aromatic hydrocarbons (PAHs) and high-DBE oxygenated PAHs, mainly from fossil fuel combustion, were positively associated with interleukin (IL)− 6, a cytokine related to oxidative homeostasis. Oxidized secondary species, particularly maleic and phthalic anhydrides, were negatively associated with IL-2/IL-8, which changed by − 3.8% to − 16.4% per one-fold increase in the abundance of the secondary source, indicating the immune disorders in response to the oxidized aerosols. Mediation analysis demonstrated the necessity of transformation products between atmospheric oxidation capacity and IL-2/IL-8 inhibition. This study provides new information on particulate electrophilic compounds and highlights the role of atmospheric chemistry in specific immune disorders.

Short-term exposure to fine particulate matter and its constituents may affect renal function via oxidative stress: A longitudinal panel study

Exposure to fine particulate matter (PM2.5) has been reported to increase the risks of chronic kidney disease. However, limited research has assessed the effect of PM2.5 and its constituents on renal function, and the underlying mechanism has not been well characterized. We aimed to evaluate the association of PM2.5 and its constituents with kidney indicators and to explore the roles of systematic oxidative stress and inflammation in the association. We conducted a longitudinal panel study among 35 healthy adults before-, intra- and after-the 2019 Wuhan Military World Games. We repeatedly measured 6 renal function parameters and 5 circulating biomarkers of oxidative stress and inflammation at 6 rounds of follow-ups. We monitored hourly personal PM2.5 concentrations with 3 consecutive days and measured 10 metals (metalloids) and 16 polycyclic aromatic hydrocarbons (PAHs) components. The linear mixed-effect models were applied to examine the association between PM2.5 and renal function parameters, and the mediation analysis was performed to explore potential bio-pathways. PM2.5 concentrations across Wuhan showed a slight decrease during the Military Games. We observed significant associations between elevated blood urea nitrogen (BUN) levels and PM2.5 and its several metals and PAHs components. For an interquartile range (IQR) increase of PM2.5, BUN increased 0.42 mmol/L (95% CI: 0.14 to 0.69). On average, an IQR higher of lead (Pb), cadmium (Cd), arsenic (As), selenium (Se), thallium (Tl) and Indeno (1,2,3-cd) pyrene (IPY) were associated with 0.90, 0.65, 0.29, 0.27, 0.26 and 0.90 mmol/L increment of BUN, respectively. Moreover, superoxide dismutase was positively associated with PM2.5 and mediated 18.24% association. Our research indicated that exposure to PM2.5 might affect renal function by activating oxidative stress pathways, in which the constituents of Pb, Cd, As, Se, Tl and IPY might contribute to the associations.

Molecular characteristics of organic matter obtained from biochar by carbon disulfide/acetone synergistic extraction

Environmental context Novel insight into BEOMcc is provided by fractionation and FTICR MS. Sub-fractions of biochar were extracted due to the chemical properties of the organic solvents. BEOMcc has a carbon fixation effect, and so is likely beneficial to the growth of plants and microorganisms. Rationale Since carbon disulfide (CS2) has a strong penetrating ability and acetone (CH3COCH3) can dissolve tiny biochar particles, a mixture of these compounds may efficiently extract organic matter from biochar. The extraction efficacy and structural features of a mixture of CH3COCH3 and CS2 (1:1) were tested in this study. Π–Π interactions between CS2 and CH3COCH3 increase the solubility of organic matter in the extraction process. Methodology We used a mixture of CH3COCH3 and CS2 (1:1) to extract organic matter from soybean straw biochar (BEOMcc) and applied Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) for analysis. Results We found that CS2/CH3COCH3 tended to extract refractory substances, and the resulting extract contained a higher number of heteroatoms than the CS2-extractable fraction (1.34 times). Discussion The H/C ratio of BEOMcc is lower than that of CS2- and CH3COCH3-extractable components. The aromatic component of BEOMcc accounts for 52.47%, which is higher than the contribution to CS2-extractable organic matter of approximately 49.9%. The polycyclic aromatic hydrocarbon component of BEOMcc is beneficial to improving soil stability. The organic matter fraction of BEOMcc has a lower H/C ratio. The C/N ratio of BEOMcc is lower than that of the CS2- and CH3COCH3-extractable components. This result reveals that BEOMcc may provide a significant environmental benefit. The polarity of BEOMcc is between that of CS2- and CH3COCH3-extractable components. Implications for future research In this study, the composition of BEOMcc was assessed at the molecular level, and the extraction method was continuously improved to provide more extraction options for the study of biochar–pollutant interactions. This method can be used to extract organic matter that is difficult to extract by conventional methods, which is more closely bound to the biochar framework. It can provide a technical basis for the in‐depth characterisation and utilisation of biochar organic matter.

Anthracene and Pyrene Biodegradation Performance of Marine Sponge Symbiont Bacteria Consortium.

Every petroleum-processing plant produces sewage sludge containing several types of polycyclic aromatic hydrocarbons (PAHs). The degradation of PAHs via physical, biological, and chemical methods is not yet efficient. Among biological methods, the use of marine sponge symbiont bacteria is considered an alternative and promising approach in the degradation of and reduction in PAHs. This study aimed to explore the potential performance of a consortium of sponge symbiont bacteria in degrading anthracene and pyrene. Three bacterial species (Bacillus pumilus strain GLB197, Pseudomonas stutzeri strain SLG510A3-8, and Acinetobacter calcoaceticus strain SLCDA 976) were mixed to form the consortium. The interaction between the bacterial consortium suspension and PAH components was measured at 5 day intervals for 25 days. The biodegradation performance of bacteria on PAH samples was determined on the basis of five biodegradation parameters. The analysis results showed a decrease in the concentration of anthracene (21.89%) and pyrene (7.71%), equivalent to a ratio of 3:1, followed by a decrease in the abundance of anthracene (60.30%) and pyrene (27.52%), equivalent to a ratio of 2:1. The level of pyrene degradation was lower than that of the anthracene due to fact that pyrene is more toxic and has a more stable molecular structure, which hinders its metabolism by bacterial cells. The products from the biodegradation of the two PAHs are alcohols, aldehydes, carboxylic acids, and a small proportion of aromatic hydrocarbon components.

Effect of oxygen concentration on combustion residues of polymerised styrene-butadiene rubber 1502

Polymerised styrene-butadiene rubber (SBR) 1502 is one of the most common petrochemical products. During the identification of fire evidence, the combustion residues of SBR 1502 highly interfere with the identification of gasoline, a fire accelerant. By conducting thermogravimetric–differential scanning calorimetry (TG-DSC) experiments at various oxygen concentrations (0, 14, and 21 vol.%), the TG-DSC combustion characteristic behaviour of SBR 1502 was investigated. Gas chromatography–mass spectrometry was used to examine the combustion residues at different stages. The results indicated a lack of 2,3-dimethylnaphthalene among the combustion residue of SBR 1502 at the oxygen concentration of 0 and 14 vol.%, thus effectively avoiding the interference of this combustion residue in gasoline identification. The results of the quantitative analysis revealed aromatic hydrocarbon components as the most interfering components for all oxygen concentration and temperature. The combustion residues of SBR 1502 at different oxygen concentrations and combustion stages exhibited different degrees of interference in gasoline identification. Therefore, qualitative and quantitative analyses (hierarchical clustering analysis) were employed to eliminate interference from SBR 1502 in gasoline identification. The results provide theoretical support during the fire identification process.

First screening of biocides, persistent organic pollutants, pharmaceutical and personal care products in Antarctic phytoplankton from Deception Island by FT-ICR-MS

In recent years, the Antarctic territory has seen a rise in the number of tourists and scientists. This has led to an increase in the anthropogenic footprint in Antarctic ecosystems, namely in terms of emerging contaminants, such as Biocides, Persistent Organic Pollutants (POPs) as well as Pharmaceutical and Personal Care Products (PPCPs). Yet scarce information on the presence of these emerging contaminants is available for trophic compartments, especially the phytoplankton community. Using high resolution Fourier-transform ion cyclotron-resonance mass spectrometry (FT-ICR-MS), an untargeted screening of the metabolome of the phytoplankton community was performed. Seventy different contaminant compounds were found to be present in phytoplankton collected at two sites in Port Foster Bay at Deception Island. These emerging contaminants included 1 polycyclic aromatic hydrocarbon (PAH), 10 biocides (acaricides, fungicides, herbicides, insecticides and nematicides), 11 POPs (flame retardants, paints and dyes, polychlorinated biphenyl (PCB), phthalates and plastic components), 5 PCPs (cosmetic, detergents and dietary compounds), 40 pharmaceutical compounds and 3 illicit drugs. Pharmaceutical compounds were, by far, the largest group of emerging contaminants found in phytoplankton cells (anticonvulsants, antihypertensives and beta-blockers, antibiotics, analgesic and anti-inflammatory drugs). The detection of several of these potentially toxic compounds at the basis of the marine food web has potentially severe impacts for the whole ecosystem trophic structure. Additionally, the present findings also point out that the guidelines proposed by the Antarctic Treaty and Protocol on Environmental Protection to the Antarctic Treaty should be revisited to avoid the proliferation of these and other PPCPs in such sensitive environments.

The feasibility study of single-hydrocarbylbenzene/n-heptane model diesel fuels for diesel characterization

Single-hydrocarbylbenzenes are an important component of diesel. Understanding the mechanism of single-hydrocarbylbenzenes in engine combustion and emissions is of great significance in the construction and development of model diesel fuels. In this work, we used n-heptane as a representative components of alkanes, and toluene, n-butylbenzene and 1,2, 4-trimethylbenzene as the representative components of aromatic hydrocarbons and studied the effects of toluene/n-heptane, n-butylbenzene/n-heptane, and 1,2,4-trimethylbenzene/n-heptane blend fuels on the combustions and emissions performance of an engine. The test fuels include pure diesel (D100) and other six single-hydrocarbylbenzene/n-heptane blends (toluene, n-butylbenzene and 1,2,4-trimethylbenzene (T20, BBZ20, TMB20 and T30, BBZ30, TMB30) which were added to n-heptane at volume ratios of 20% and 30%). The experimental results showed that the peak IP increased, and CA50 advanced after the addition of single-hydrocarbylbenzenes. The IP, HRR, ID, and CA50 curves of BBZ20 were the most consistent with those of D100. Moreover, the soot emissions of single-hydrocarbylbenzene blended fuels were low, and the NOx, CO, and THC emissions were higher than those of D100. At EGR < 20%, the difference between NOx emissions of D100 and BBZ or TMB was within 2.6%. Under all EGR rates, the soot emissions of BBZ20 were the closest to those of D100 (especially when the EGR rate is 40%, the difference in soot emissions between BBZ20 and D100 is only 57.8%), and the CO emissions of TMB20 closest to those of D100 (the range of difference is 5–13.3%).

Vertical distribution of polycyclic aromatic hydrocarbons in the brackish sea water column: ex situ experiment.

BackgroundOil spills can cause severe damage within a marine ecosystem. Following a spill, the soluble fraction of polycyclic aromatic hydrocarbons is rapidly released into the water column. These remain dissolved in seawater over an extended period of time, even should the insoluble fraction be removed. The vertical distribution of the aromatic hydrocarbon component and how these become transferred is poorly understood in brackish waters. This study examines the vertical distribution of polycyclic aromatic hydrocarbons having been released from a controlled film of spilled oil onto the surface of brackish water.MethodsThe study was undertaken under controlled conditions so as to minimize the variability of environmental factors such as temperature and hydrodynamics. The distribution of polycyclic aromatic hydrocarbons was measured in the dissolved and suspended phases throughout the 1 m water column with different intensity of water sampling: 1, 2, 4, 7, 72, 120, 336, 504 and 984 h.ResultsThe total concentration of polycyclic aromatic hydrocarbons ranged from 19.01 to 214.85 ng L–1 in the dissolved phase and from 5.14 to 63.92 ng L–1 in the suspended phase. These hydrocarbons were released immediately following a controlled spill attaining 214.9 ng L–1 in the dissolved phase and 54.4 ng L–1 in the suspended phase near the cylinder bottom after 1–2 h. The 2–3 ring polycyclic aromatic hydrocarbons dominated in the dissolved phase (60–80%), whereas the greater amount of 4–6 ring polycyclic aromatic hydrocarbons (55–90%) occurred in the suspended phase. A relatively low negative correlation (rS = –0.41) was determined between the concentration of phenanthrene and suspended matter, whereas a high negative correlation (r = − 0.79) was found between the concentration of pyrene and suspended matter. Despite the differences in the relationships between the concentration ratio and amount of suspended matter the obtained regressions allow roughly to predict the concentration of polycyclic aromatic hydrocarbons.

Determination and Origin Apportionment of Polycyclic Aromatic Hydrocarbons (PAHs) in Posidonia oceanica Samples around Gökçeada

The study was carried out in Gokceada, located in the North Aegean Sea in 2017, during winter and summer seasons and the concentrations of 16 polycyclic aromatic hydrocarbon (PAH) components were determined in P. oceanica type seagrass samples. Total PAH (TPAH) values ranged from 190.8 to 7668.7 ng g−1 dw during the sampling period. In addition, the source of pollution was investigated by using PAH ratios. According to the fluoranthene (FA) /pyrene (PY) ratio in the winter period, the origin of pollution is mostly pyrolytic, while in the summer period, according to the fluoranthene (FA) /pyrene (PY) and benzo(a)anthracene (BaA) /chrysene (CHR) ratio, the pollution origin was found to be petrogenic.

Effects of polycyclic aromatic hydrocarbons (PAHs) from different sources on soil enzymes and microorganisms of Malus prunifolia var. Ringo

ABSTRACT The main components of polycyclic aromatic hydrocarbons (PAHs) and the degree of contamination of soil with different oils (gasoline, diesel oil, and lubricating oil) were examined. Malus prunifolia var. Ringo was planted in soil contaminated by gasoline, diesel oil, or lubricating oil with three different concentrations which were low concentration (0.1 g kg−1), medium concentration (0.2 g kg−1), and high concentration (0.5 g kg−1) in April 2016. The changes in PAH contents and soil index in the soil were measured from July to September 2016. It showed that more naphthalene, anthracene, phenanthrene, fluorene, and flexion were detected in the three oil treatments. From July to September, three high-concentration oil treatments had inhibited soil urease activity in soil significantly except the diesel oil treatment with high concentration in August. The diesel and lubricating oil treatments had inhibited phosphatase and invertase activities in soil significantly. Three oil treatments inhibited the number of bacteria significantly in July. The total number of bacteria and fungi was highest in gasoline, and the total number of actinomycetes was highest in lubricating oil. The three oils affected the soil enzyme activity and the number of soil microorganisms and caused some damage to the soil ecological environment.

Effect of pine-tar bath on disease severity in moderate-to-severe childhood eczema: an investigator-blinded, crossover, randomized clinical trial

Background Atopic dermatitis (AD) is a chronic inflammatory disease associated with pruritus and sleep loss. Pine-tar has long been used for various chronic skin conditions in which its polycyclic aromatic hydrocarbon (PAH) component is anti-inflammatory and its resin acids antiseptic. The null hypothesis of this trial is that there is no difference in clinical efficacy between a pine-tar product and its vehicle for AD. Methods A 3-month, investigator-blinded, crossover, randomized control trial (RCT) was conducted in which each patient was assigned to bathing with pine-tar bath oil for one month and vehicle bath oil for another, with a washout period of 1-month in-between. Acceptability and efficacy of the bath products were measured. Disease severity scores (scoring atopic dermatitis (SCORAD) and patient-oriented eczema measure (POEM), quality of life questionnaires, noninvasive skin biophysiological measurements, blood IgE levels, and Staphylococcus aureus (SA) colonization status were assessed before and following bathing. Results Significant improvements were found in total SCORAD (p = .030), POEM (p = .004), SA colonization status (p = .002), and log-transformed IgE level (p = .009) among patients who bathed with pine-tar in the overall RCT study using intention-to-treat analysis. For per protocol analysis, significant improvements were found in total SCORAD (p = .024), objective SCORAD (p = .011), extent (p = .014), intensity (p = .032), pruritus (p = .047), POEM (p = .044), SA colonization status (p = .035), and log-transformed IgE level (p = .028). Acceptability to both bath-oils was good, and no product-related serious adverse events were recorded. Conclusions Bathing with pine-tar is an efficacious and recommendable adjuvant practice for AD patients. Disease improvement is associated with reduction of SA and IgE.

Quantum chemical calculation to elucidate the biodegradation pathway of methylphenanthrene by green microalgae

Alkylated polycyclic aromatic hydrocarbons (APAHs) are the main components of polycyclic aromatic hydrocarbons (PAHs) in petroleum-contaminated waters. In our study, three kinds of green microalgae (Pseudokirchneriella subcapitata, Chlorella vulgaris and Scenedesmus obliquus) were shown to degrade six kinds of methylphenanthrenes (1-methylphenanthren, 2-methylphenanthrenem, 3-nmmethylphenanthrene, 4-methylphenanthren, 9-methylphenanthrene and 3,6-dimethylphenanthrene) with different degrading abilities. Among the six methylphenanthrenes, 99.8% of 1-methylphenanthrene (1-MP) was removed and 75.6% of 3,6-dimethylphenanthrene (3,6-DMP) was removed by P. subcapitata after 7 days of incubation. The metabolites of 1-MP and 3,6-DMP were identified by gas chromatograph-mass spectrometer (GC-MS). Six metabolites of 1-MP and one metabolite of 3,6-DMP were found, they were all monohydroxylated methylphenanthrenes. The –OH group was added to either methyl-group or benzene ring through the monooxygenase system, and the methyl-group attack was the main pathway. This research increases our knowledge of the degrading ability of APAHs by green microalgae and offers information for the bioremediation of APAHs. Quantum chemical calculation was conducted to elucidate the biodegradation metabolites of methylphenanthrene by green microalgae, which is a helpful tool in the bioremediation of environmental pollution.