Saturated Alkanes Research Articles

Exploring Pyrolysis Gaseous Tar Distribution and Combustion Temperature Identification in Coal Fire

ABSTRACT This paper establishes correlations between various pyrolysis products collected from the vicinity of the fire zone and the prevailing temperature using substance identification via GC-MS analysis. Further experimental comparisons among multiple substances reveal a strong correlation between phenols and temperature. This leads to the identification of temperature-specific products primarily composed of phenols, ultimately enhancing the accuracy of fire area temperature recognition. This experiment utilized a self-built fixed bed and GC-MS technology to qualitatively and quantitatively study the release characteristics of gaseous tars from lignite, long-flame coal, and gas coal at different temperatures (300°C, 350°C, 400°C, 450°C, 500°C) under pyrolysis conditions. The experimental results showed that there are significant differences in the tar components produced during pyrolysis among coals with different degrees of metamorphism. The composition ratios are all in the order of oxygen-containing organic compounds > aromatic hydrocarbons > aliphatic hydrocarbons, and the three most abundant organic compounds are phenol, o-cresol, and p-cresol. The types and quantities of organic compounds in coal pyrolysis tars are positively correlated with reaction temperature. Based on a third-order polynomial fitting of the total amount of compounds in pyrolysis tars and the corresponding temperature under pyrolysis conditions, the representative subclasses of each type of substance were further fitted. The results of the temperature correlation show that the fitting trend of phenols with temperature is similar to the overall trend and far superior to naphthalene organics and saturated alkanes. In the vertical comparison of phenolic content at different temperatures, common identifiable substances such as C8H10O and C23H32O2 are selected, and specific substance identification was provided for coal samples of different ranks of coal metamorphism. This ultimately provides a new approach for establishing a method to identify the combustion state of coal fires at 300–500°C.

Morphology‐Dependent Catalytic Activity of ZnFe2O4 Spinel Toward Light Olefins from Fischer–Tropsch Synthesis

AbstractThe shape‐defined ZnFe2O4 spinel with cubic and octahedral morphology was hydrothermally synthesized, respectively, and used as catalyst precursor for Fischer–Tropsch synthesis (FTS). The structure of ZnFe2O4 spinel was changed to ZnO and Fe5C2 (Fe5C2/ZnO) after reduction and carbonization. Interestingly, ZnFe2O4 with cubic morphology exhibited much higher catalytic activity and selectivity toward low‐carbon olefins (C2–C4) than the octahedral one under identical conditions, and the latter tended to produce the saturated alkanes. The primary properties of ZnFe2O4 materials before and after reduction were systematically studied through a series of characteristic technologies to reveal the difference in catalytic performance between the two ZnFe2O4 spinels with different morphologies.

CO2 Adsorption onto Water-Bearing Shale: Insights from Molecular Dynamics and Implications on CO2 Prestorage Fracturing

Summary Hydraulic fracturing coupled with CO2 injection or CO2 prestorage fracturing is a pivotal technique for enhancing shale oil recovery. Besides, geological CO2 storage offers a feasible solution for mitigating global warming. However, after hydraulic fracturing, the shale matrix is in a water-bearing environment. The complex mechanisms associated with the impact of the injected CO2 on shale oil recovery in the water-bearing kerogen matrix remain unclear. In this work, we explored the adsorption mechanism of five representative components of shale oil in water-bearing kerogen through molecular dynamics (MD) simulation, which may provide useful microscopic insights for industrial CO2 prestorage fracturing. Our research revealed that CO2 could decrease the adsorption capacity of n-octane (OCT; saturated alkanes), thiophene (THIOP), and naphthalene rings (NAPs; aromatic hydrocarbons) onto the kerogen, which consequently improved the recovery of these components. Conversely, the adsorption capacity of pyridine (PYR) and n-octadecanoic acid (STE) was boosted upon the CO2 introduction. This could be attributed to the fact that after CO2 injection, both the quantity and the lifetime of hydrogen bonds between these two components and kerogen were increased. The interaction energy between these two components and the water-bearing kerogen also increased, which was in-line with the changes in molecular van der Waals (vdW) surface electrostatic potential (ESP) and the spatial distribution function (SDF). In addition, to reveal the deeper mechanism, the interactions between the specific sites or functional groups on the kerogen and the different components are analyzed to predict the intermolecular charge transfer. It is believed this work may offer useful insights into the design and implementation of CO2 prestorage fracturing for improved shale oil recovery and CO2 geological storage.

Needle growth of Nb2O5 nanoparticles on BiOCl nanosheets to fabricate S-scheme heterojunction with oxygen vacancies for enhanced photooxidation of cyclohexane

The exploration of cost-efficient, environmentally friendly, and high-efficacy photocatalysts for the enhanced selective photooxidation of cyclohexane to KA oil (cyclohexanone (CHA-one) and cyclohexanol (CHA-ol)) is a pivotal challenge in the industrial realm. Herein, the present study focuses on the synthesis of needle-like S-scheme heterojunction photocatalysts with oxygen vacancies, which are achieved by the needle growth integration of nano-sized Nb2O5 particles onto the BiOCl nanosheets. Remarkably, the 40 % Nb2O5/BiOCl composites exhibited superior performance in the solvent-free photooxidation of cyclohexane at room-temperature and under atmospheric pressure. The production yield of KA oil was 180.3 μmol (CHA-one/CHA-ol molar ratio = 3.5), and exceptional selectivity towards KA oil, reaching up to 99.3 %. The enhanced photocatalytic efficiency in cyclohexane oxidation can be attributed to the unique S-scheme heterogeneous interfaces with specific nanoneedle morphology, which result in the enhanced photonic absorption, effective charge carrier separation, a high density of oxygen vacancies, and the exposure of the highly reactive (001) plane of BiOCl. The excellent interfacial charge separation and transfer pathways of S-scheme heterojunction are disclosed by the in-depth EPR analysis and DFT calculations. These insights highlight the significant potential of the needle-like Bi-based S-scheme heterojunction photocatalysts for the efficient photooxidation of saturated alkanes.

Mechanistic understanding of oxygen spillover enables efficient propane combustion over Pt/AlSOx catalyst

Understanding of the mechanism of saturated alkanes catalytic combustion is crucial for the petrochemical industrial exhaust elimination. Noble metals are commonly proposed to be the active sites for C–H bond activation of saturated alkanes, whereas the critical role of support is largely underestimated. Herein, we reveals a novel pathway for propane activation and combustion on acidic support of Pt catalyst, driven by oxygen spillover, which differs significantly from previously reported reaction mechanisms. Specifically, the Pt/AlSOx-I catalyst was prepared by pyrolyzing the Al2(SO4)3 sol–gel to obtain the acidic micro-mesoporous AlSOx support, followed by loading the Pt active sites using wetness impregnation. In comparison to Pt catalysts supported by Al2O3 nanoparticles (10 nm) or commercially available common γ-Al2O3, the Pt/AlSOx-I catalyst demonstrates superior catalytic activity for propane combustion. It is found that gaseous oxygen species activated on Pt active sites spillovers to acidic support of Pt/AlSOx-I and then drives propane to activation and further oxidation on acidic support, thereby remarkably decreasing the apparent activation energies (Ea) from 112.4 to 72.0 kJ·mol−1. Kinetic results suggest that the negative effect of oxygen competitive adsorption is weakened because propane can be activated on the acidic AlSOx support. Additionally, high proportion of metallic Pt species benefits to gaseous oxygen activation as observed on Pt/AlSOx-R, leading to the further increased catalytic activity with highest specific mass reaction rate of 170.2 μmol gPt−1 s−1 and TOFPt of 0.289 s−1 at 220 °C. Our primary results provide novel insights into revealing the reaction mechanism of saturated alkanes combustion on dual active sites.

Simultaneous desulfurization and dearomatization of simulated straight-run diesel with novel green DBN-based ionic liquids

Given the surplus of diesel fuel in China and the extensive utilization of renewable energy sources, there is a growing inclination to eliminate organic sulphur and aromatic hydrocarbons from diesel fuel for its application as high-quality ethylene cracking feedstock. In this study, a series of 1,5-diazabicyclo[4.3.0]non-5-ene (DBN)-based ionic liquids with [DBNH]+ as the cation and imidazole as the anion were designed and synthesized for the simultaneous desulfurization and dearomatization of straight-run diesel fuel. Considering factors such as extractant stability, residue content in oil, and separation performance, [DBNH][Tr], exhibiting excellent performance characteristics, was screened as the optimal extractant. Following three-stage cross-flow extraction with an extractant/oil ratio of 3:1 at 30 °C, complete removals of sulfides (benzothiophene) and polycyclic aromatic hydrocarbons (1-methylnaphthalene) were achieved while saturated alkanes reached up to 95.8 wt%, making it suitable for ethylene cracking applications. The interaction mechanisms between ionic liquids and oil components were revealed by atoms in molecules (AIM) topology analysis, independent gradient model based on Hirshfeld partition (IGMH) analysis, and symmetric adaptive perturbation theory energy decomposition techniques, revealing that dispersion-dominated van der Waals (VDW) forces primarily govern interactions due to π-π stacking.

Generation of abnormal distributions of inter- and intramolecular δ13C compositions in hydrocarbons from gold tube pyrolysis of an Australian torbanite

Abnormal stable carbon isotopic (δ13C) compositions, deviating from the conventional order of δ13C1 < δ13C2 < δ13C3, are frequently observed in natural gas reservoirs. For thermogenic gas, these anomalies, such as δ13C1 < δ13C3 < δ13C2 or δ13C1 > δ13C2 > δ13C3, have multiple formation mechanisms including gas mixing in conventional systems and desorption processes of gaseous hydrocarbons in unconventional shale gas systems due to their inconsistency with Rayleigh fractionation processes. Considering distinct reaction pathways (e.g., C1 polymerized to C2), these aberrant δ13C signatures are often construed as intrinsic hallmarks of extensively evolved natural gas. However, on the basis of gas generation simulation, not all findings exhibit abnormal δ13C values, hinting at multifaceted and intricate mechanisms governing the isotopic fractionation of alkane gas components. This study conducted gold tube pyrolysis of an Australian torbanite, revealing four distinct types of δ13C anomalies in hydrocarbon classes. Polycyclic aromatic hydrocarbons (PAHs) exhibited δ13C values more negative than co-occurring n-alkanes. δ13C3 displayed a negative trend shift from EasyRo = 3.5 %, resulting in a partially δ13C-reversed gas (δ13C1 < δ13C3 < δ13C2) formed at EasyRo ≈ 4.1 %. Moreover, intramolecular δ13C3 (both terminal and central carbons, termed δ13Ca and δ13Cb, respectively) reversed alongside the overall δ13C3 trend. Additionally, the evolution of site preference in δ13C3 (termed ‰SP = δ13Ca – δ13Cb) transitioned from progressively negative to positive. The results of this study demonstrate that the potential conversion between saturated hydrocarbons, aromatic hydrocarbons, and alkane gases is at least partially responsible for δ13C anomalies, but also that gaseous hydrocarbons formed from other fractions at high maturity cannot be ruled out, such as kerogen and pyrobitumen.

Dual-sites passivation for efficient and stable carbon-based perovskite solar cells

It has been proven that dual-active-site passivation is more effective than single-site passivation in mitigating surface defects of carbon-based perovskite solar cells (C-PSCs). Therefore, it is imperative to explore new agents capable of inducing dual-active-site passivation effect. This work strategically employs potassium laurate (KLA) as a surface passivating agent, which stands out due to its extended saturated alkane chains and carboxylate groups, offering dual-active sites encompassing carboxylate ions and K+ cations. Carboxylate ions play a pivotal role in passivating low-coordinated Pb2+ defects, while K+ metal cations are anticipated to address anionic defects. The champion C-PSC achieves an impressive power conversion efficiency (PCE) of 16.10%, increased from 14.35% of the original. The incorporation of KLA serves to diminish surface defects within the film and suppress non-radiative recombination at the interface by dual-sites passivation, thereby establishing itself as a valuable technique for enhancing the efficiency and durability of C-PSCs.

Chemical and Transcriptomic Analyses of Leaf Cuticular Wax Metabolism in Ammopiptanthus mongolicus under Osmotic Stress.

Plant cuticular wax forms a hydrophobic structure in the cuticle layer covering epidermis as the first barrier between plants and environments. Ammopiptanthus mongolicus, a leguminous desert shrub, exhibits high tolerances to multiple abiotic stress. The physiological, chemical, and transcriptomic analyses of epidermal permeability, cuticular wax metabolism and related gene expression profiles under osmotic stress in A. mongolicus leaves were performed. Physiological analyses revealed decreased leaf epidermal permeability under osmotic stress. Chemical analyses revealed saturated straight-chain alkanes as major components of leaf cuticular wax, and under osmotic stress, the contents of total wax and multiple alkane components significantly increased. Transcriptome analyses revealed the up-regulation of genes involved in biosynthesis of very-long-chain fatty acids and alkanes and wax transportation under osmotic stress. Weighted gene co-expression network analysis identified 17 modules and 6 hub genes related to wax accumulation, including 5 enzyme genes coding KCS, KCR, WAX2, FAR, and LACS, and an ABCG transporter gene. Our findings indicated that the leaf epidermal permeability of A. mongolicus decreased under osmotic stress to inhibit water loss via regulating the expression of wax-related enzyme and transporter genes, further promoting cuticular wax accumulation. This study provided new evidence for understanding the roles of cuticle lipids in abiotic stress tolerance of desert plants.

Differences and distribution of quality components in Fu brick tea around fungal fermentation

The differences in and distributions of the quality components of Fu brick tea before and after flowering (also called fungal fermentation and known as “Fahua” in China) remain unclear, and the standard of judging quality by the number of golden flowers (GFs; yellow closed capsules of Eurotium cristatum spores) by consumers lacks a scientific foundation. In this study, Fu brick tea (AFT) was obtained from pre-flower raw dark tea (BFT) through the traditional processing of Fu brick tea. The AFT was then hand-selected and divided into pure tea (SFT) and GFs. It was found that the flavonoid, tea polyphenol, free amino acid, aqueous extract, and ester-type catechin content in the AFT were all significantly lower than in the BFT (p < 0.05); the content of 34 types of volatile compound was significantly higher (26 alkanes, 4 alkenes, 2 alcohols, 1 ester, 1 aldehyde) (p < 0.05), and the content of 14 types of volatile compound was significantly lower (6 alkanes, 4 alcohols, 2 esters, 1 ketone, 1 alkene) than in the BFT (p < 0.05). Furthermore, the content of 39 types of nonvolatile substances, including four carboxylic acids, three flavonoids, and D-Arabitol, amino acids and their derivatives, was significantly higher in the AFT (p < 0.05). The content of flavonoids and their derivatives, including 24 types of saturated alkanes and seven types of aldehydes and esters of volatile compounds (3 alkenes, 2 alcohols, 1 ester, and 1 aldehyde) (p < 0.05), was significantly higher in the SFT than in the GFs (p < 0.05). The GFs had significantly higher content of water-soluble leachate, maltose, glycosylated flavonoids, D-salicylose, and amino acids and their derivatives than the SFT (p < 0.05). Widdrol, linalool, N-octanal, and 25 other volatile compounds (9 alkenes, 9alcohols, s aldehydes, 1 ester, 1 alkane, 1 ketone, 1 Naphthalene) were detected only in the GFs.

Quantification of the composition of pyrolysis oils of complex plastic waste by gas chromatography coupled with mass spectrometer detector.

Waste valorisation through pyrolysis generates solid, liquid and gaseous fractions that need to be deeply characterised in order to try to recover secondary raw materials or chemicals. Depending on the waste and the process conditions, the liquid fraction obtained (so-called pyrolysis oil) can be very complex. This work proposes a method to quantitatively measure the composition of pyrolysis oils coming from three types of polymeric waste: (1) plastic packaging from sorting plants of municipal solid waste, (2) plastic rich fractions rejected from sorting plants of waste of electrical and electronic equipment and (3) end-of-life carbon/glass fibre reinforced thermoset polymers. The proposed methodology uses a gas chromatography (GC) coupled with mass spectrometer detector (MS) analytical technique, a certified saturated alkanes' mix, an internal standard and fourteen model compounds. Validation of the methodology concluded that the average relative error was between -59 wt% and +62 wt% (with standard deviations between 0 wt% and 13 wt%). Considering that the state-of-the-art scenario to quantify complex plastic pyrolysis oils as a whole is almost none and that they are usually evaluated only qualitatively based on the area percentage of the GC-MS chromatograms, the presented quantification methodology implies a clear step forward towards complex pyrolysis oil compositional quantification in a cost-effective way. Besides, this quantification methodology enables determining what proportion is being detected by GC-MS with respect to the total oil. Finally, the presented work includes all the Kováts RI for complex temperature-program gas chromatography of all the signals identified in the analysed pyrolysis oils, to be readily available to other researchers towards the identification of chemical compounds in their studies.

Investigation on molecular characteristics of organic compounds during a full-scale landfill leachate treatment process based on non-targeted analysis

In this study, a new methodology for evaluating full-scale landfill leachate treatment processes by non-targeted analysis using comprehensive two-dimensional gas chromatography quadrupole time-of-flight mass spectrometry (GC × GC-QTOF-MS) was proposed. The method revealed the chemical complexity of organic compounds in landfill leachate samples at the molecular level and evaluated the removal efficiency of the anaerobic-anoxic-oxic (A2O) - membrane bioreactor (MBR) - nanofiltration (NF) treatment process in conjunction with multi-level classification of organic compounds. Results showed that the results of non-targeted analysis combined with multi-level classification of organic compounds had a significant correlation with the conventional water quality parameters and can be used to evaluate the treatment process. A total of 2508 organic compounds were detected in 6 samples. 17 emerging contaminants (ECs) with known potentially hazards were detected, including Diisobutyl Phthalate (DIBP), which is toxic to male reproduction and development, and 4-Tert-Butylphenol, which causes endocrine disruption in animals. The removal rate of organic compounds by this full-scale landfill leachate treatment processes reached 79.14%. The anaerobic tank played a crucial role with 64.98% contribution. For compounds, the removal rate of heterocyclics was as high as 94.67%, and the removal rate of aliphatics was poor, only 63.49%. This treatment process had almost perfect removal effect on the steroids in alicyclics and phenols in aromatics, but poor treatment effect on saturated alkanes in aliphatics and naphthenes in alicyclics. This study provides a methodology for accurate assessment of the molecular level of treatment processes, new insights for process optimization in waste treatment plants, and data support for the detection of emerging contaminants. The environmental hazards of landfill leachate can be further evaluated in the future in conjunction with ecotoxicity assessment studies.

Photocatalytic Semi-Hydrogenation of Alkynes: A Game of Kinetics, Selectivity and Critical Timing.

The semi-hydrogenation reaction of alkynes is important in the fine chemicals and pharmaceutical industries, and it is thus important to find catalytic processes that will drive the reaction efficiently and at a low cost. The real challenge is to drive the alkyne-to-alkene reaction while avoiding over-hydrogenation to the saturated alkane moiety. The problem is more difficult when dealing with aromatic substitution at the alkyne center. Simple photocatalysts based on Palladium tend to proceed to the alkane, and stopping at the alkene with good selectivity requires very precise timing with basically no timing tolerance. We report here that the goal of high conversion with high selectivity could be achieved with TiO2-supported copper (Cu@TiO2), although with slower kinetics than for Pd@TiO2. A novel bimetallic catalyst, namely, CuPd@TiO2 (0.8% Cu and 0.05% Pd), with methanol as the hydrogen source could improve the kinetics by 50% with respect to Cu@TiO2, while achieving selectivities over 95% and with exceptional timing tolerance. Further, the low Palladium content minimizes its use, as Palladium is regarded as an element at risk of depletion.

An Improved Approximation for DIPPR-Based Predicting Speed of Sound in Long-Chained n-Alkanes

IIn this short communication, we revise a correlation for the saturated liquid isothermal compressibility based on the data available in DIPPR (Postnikov, 2016) which considers the molecular non-sphericity and addresses a problem of predicting speeds of sound in saturated long-chained alkanes. In addition, we correct a misprint appeared in the cited work and provide programming code used for the realisation of the proposed calculations.

A GC/C/IRMS-based method for position-specific carbon isotopic analysis of saturated long chain fatty acids

Intramolecular carbon isotope profiles (13C/12C) of mid- and long-chain saturated fatty acids represent a potentially rich source of pathway and flux information on fatty lipid biosynthesis. Accessing the PSIC-13C (position-specific carbon isotope composition) of saturated long chain fatty acids, however, proves a challenge as neither 13C NMR, nor online pyrolysis, can measure all carbons successfully. We have developed a wet chemistry procedure (α-bromination, α-hydrolysis and decarboxylation) to stepwise shorten the targeted saturated fatty acid, followed by GC/C/IRMS (gas chromatography/combustion/isotope ratio mass spectrometry) measurement of the 13C/12C ratios of fatty acids, with minimal purification. Isotope mass balance was then applied to calculate the 13C/12C ratios of individual carbons. The triplicated PSIA precision varies from position to position in the range 3.95–5.25 mUr (averaging 4.44 mUr, equivalent to ‰).Applying this method to a commercial C16:0 fatty acid of C3 botanical origin revealed an intramolecular odd-over-even 13C enrichment pattern, consistent with that obtained with 13C NMR. Although PSIA-13C was attempted only on a single fatty acid, the method can potentially be applied to obtain PISC-13C for all fatty acids in a mixture simultaneously, and to long chain saturated alkanes after proper functionalization. The method should prove useful in studies of lipid metabolism and biogeochemistry as both saturated long chain fatty acids and alkanes are the dominant organic archives of climate in petroleum deposits, sediments and soils.

Effects of Long-Term Grazing on Feed Intake and Digestibility of Cattle in Meadow Steppe

(1) Estimation of grazing livestock intake is the basis for studying animal–plant relationships and the nutritional status of grazing livestock and has important implications for grassland composition and productivity. (2) We used the saturated alkanes method to determine the feed intake and vegetation nutrient digestibility of livestock at different grazing intensities and in different months. (3) We found that C31 had the highest concentration in both pasture and fecal output, and the average recovery of C31 was 77.99%. The different grazing intensities significantly affected livestock intake. As the grazing intensity increased, there was a decreasing trend of livestock intake and the highest livestock feed intake was 6.11 kg DM/day in light grazing. With the increase in grazing season months, the highest livestock intake was 6.67 kg DM/day in the cold period in September. The month also had a significant effect on the digestibility of livestock for all nutrient variables when compared to the grazing intensity. Livestock weight and medium palatability species are more important for livestock intake. (4) Our study provides a more accurate measurement of grazing livestock intake, which can be used as a reference for the scientific management of grazing livestock and the rational use of grazing pastures.

The Transport of Charged Molecules across Three Lipid Membranes Investigated with Second Harmonic Generation.

Subtle variations in the structure and composition of lipid membranes can have a profound impact on their transport of functional molecules and relevant cell functions. Here, we present a comparison of the permeability of bilayers composed of three lipids: cardiolipin, DOPG (1,2-dioleoyl-sn-glycero-3-phospho-(1'-rac-glycerol), and POPG (1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1'-rac-glycerol)). The adsorption and cross-membrane transport of a charged molecule, D289 (4-(4-diethylaminostyry)-1-methyl-pyridinium iodide), on vesicles composed of the three lipids were monitored by second harmonic generation (SHG) scattering from the vesicle surface. It is revealed that structural mismatching between the saturated and unsaturated alkane chains in POPG leads to relatively loose packing structure in the lipid bilayers, thus providing better permeability compared to unsaturated lipid bilayers (DOPG). This mismatching also weakens the efficiency of cholesterol in rigidifying the lipid bilayers. It is also revealed that the bilayer structure is somewhat disturbed by the surface curvature in small unilamellar vesicles (SUVs) composed of POPG and the conical structured cardiolipin. Such subtle information on the relationship between the lipid structure and the molecular transport capability of the bilayers may provide clues for drug development and other medical and biological studies.

Physicochemical Assessment of the Road Vehicle Traffic Pollution Impact on the Urban Environment

Vehicle traffic pollution requires complex physicochemical analysis besides emission level measuring. The current study is focused on two campaigns of emissions measurements held in May and September 2019 in Alba Iulia City, Romania. There was found a significant excess of PM2.5 for all measuring points and PM10 for the most circulated points during May, along with significant VOC and CO2 emissions. September measurements reveal threshold excess for all PM along with increased values for VOC and CO2 emissions. These are the consequences of the complex environmental interaction of the traffic. Street dust and air-suspended particle samples were collected and analyzed to evidence the PM2.5 and PM10 sources. Physicochemical investigation reveals highly mineralized particulate matter: PM2.5 fractions within air-suspended particle samples predominantly contain Muscovite, Kaolinite, and traces of Quartz and Calcite, while PM10 fractions within air-suspended particle samples predominantly contain Quartz and Calcite. These mineral fractions originate in street dust and are suspended in the atmosphere due to the vehicles’ circulation. A significant amount of soot was found as small micro-sized clusters in PM2.5 and fine micro-spots attached over PM10 particles, as observed by Mineralogical Optical Microscopy (MOM) and Fourier Transformed Infrared Spectroscopy (FTIR). GC-MS analysis found over 53 volatile compounds on the investigated floating particles that are related to the combustion gases, such as saturated alkanes, cycloalkanes, esters, and aromatic hydrocarbons. It proves a VOC contamination of the measured particulate matters that make them more hazardous for the health. Viable strategies for vehicle traffic-related pollutants mitigation would be reducing the street dust occurrence and usage of modern catalyst filters of the combustion gas exhausting system.

Study on separation of long carbon chain aromatics/alkanes in diesel systems with DBU-based ionic liquids

Based on the structural designability of ionic liquids (ILs), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)-based ILs ([Bz-DBU]NTF2) were designed and synthesized. Their physical properties were analyzed by FT-IR, 1H NMR, DSC and TGA. Highly selective separation between aromatic and alkane by [Bz-DBU]NTF2 was achieved. Under the optimal conditions, the distribution coefficient (D) and separation selectivity (S) of [Bz-DBU]NTF2 for tetraline were 0.833 and 54.2. The IL was regenerated six times without decrease in separation selectivity, demonstrating good stability. For the multi-component simulated diesel, nearly 100% of the bicyclic alkanes could be removed by five-stage cross-flow extraction processes. While the removal rate of total aromatics reached up to 84.39 and the contents of alkanes and total saturated alkanes reached 56.64% and 96.69%, respectively. For the real diesel, after two-stage cross-flow extraction experiments, the removal rates of monocyclic, bicyclic, tricyclic aromatic hydrocarbons reached 63.9%, 91.3% and 100%, respectively. The final product reached the standard of high quality ethylene cracking feedstock.

Rapid effective treatment of waxy oily sludge using a method of dispersion combined with biodegradation in a semi-fluid state

Waxy oily sludge (WOS) from petrochemical enterprises has complex components and difficult treatment. Long-term large-scale stacking has seriously threatened human health and the ecological environment. In this paper, a new rapid and effective treatment method combining dispersion and biodegradation in a semi-fluid state was developed for the WOS. The degradation mechanism of the WOS in the bioreactor was preliminarily discussed. The component analysis results showed that the compounds with large molecular weight (M ≥ 282) in the WOS accounted for more than 50%. Among all microbial consortiums, the treatment effect of the consortium FF: NY3 = 9: 1 was the best for treating the crude oil in WOS, which was significantly different from that of a single strain (p < 0.05). Under the optimal nitrogen source NH4NO3 and the concentration of rhamnolipid, the developed high-efficiency microbial consortium (FF: NY3 = 9:1) could remove 85% of the total hydrocarbon pollutants in the 20 L semi-fluid bioreactor within 9 days. The degradation characteristics of WOS components in the bioreactor showed that the developed consortium has good degradation ability for n-alkanes (about 90%), middle- (77.35%)/long-chain (72.66%) isomeric alkanes, alkenes (79.12%), alicyclic hydrocarbons (78.9%) and aromatic hydrocarbons (62.78%). The kinetic analysis results indicated that, in comparison, the middle-chain n-alkanes, middle-chain isomeric saturated alkanes, alkenes, and alicyclic hydrocarbons were most easily removed. The removal rates of long-chain n-alkanes, long-chain isomeric saturated alkanes, and aromatic hydrocarbons were relatively low. The biological toxicity test showed that the germination rate of wheat seeds in treated waxy sludge was Significantly higher than that in untreated waxy sludge (p < 0.01). These results suggest that the new method developed in this paper can treat refractory WOS quickly and effectively. This method lays the foundation for the pilot-scale treatment of the semi-fluid bioreactor.