Removal of polyaromatic hydrocarbons from scrap tires by solvent extraction

This study analyzes polycyclic aromatic hydrocarbon (PAH) compounds released from scrap tires by GC/MS and introduces a simple extraction process at ambient conditions to remove PAHs from scrap tires. The PAH species released from scrap tires included seven PAH compounds with high molecular weight and 4- and 5-aromatic rings and total-PAH content of 159 mg/L. When scrap tires were extracted using hot water (180 °C) for 3 h, the overall removal efficiency was 53%, indicating that PAHs were not adequately removed by this method. However, using organic solvents, the overall PAH removal efficiency improved to 82% for propionic acid and 70% for acetic acid, because the mass transfer of PAHs within scrap tires increases with decreasing dielectric constant. The PAH removal efficiency was dependent on solvent type and temperature.     

固相萃取技术富集水中的多环芳烃

本文系统地研究了淋洗剂强度、用量和有机改性剂的加入对固相萃取水中多环芳烃回收率的影响。研究表明,二氯甲烷和苯的洗脱效果较好,回收率为86％-99％;当淋洗剂的用量超过1．5ml时,对多环芳烃的回收率没有明显的影响,向自来水样中加入20％有机改性剂可明显改善多环芳烃的回收效果,使回收率达到89％-102％。     

Determination of PAHs in Combustion-Related Samples and in SRM 1597, Complex Mixture of PAHs from Coal Tar

Three types of combustion sample extracts, smokeless coal, smoky coal, and wood, were analyzed for a range of polycyclic aromatic hydrocarbons (PAHs) and polycyclic aromatic sulfur heterocycles (PASH). Standard Reference Material (SRM) 1597, Complex Mixture of PAHs from Coal Tar, was also analyzed as a control sample and for the determination of a larger number of PAHs relative to those determined previously. Target analytes included many alkyl-substituted PAHs such as dimethylphenanthrenes, methylfluoranthenes, and methylpyrenes. The analytical methods included sample clean-up and the selection of specific stationary phases to accomplish unique separations of PAHs. Clean-up involved the use of normal-phase liquid chromatographic isolation of PAHs based on the number of aromatic carbons and a total PAH fraction, PAHs in the resulting fractions were separated by gas chromatography using two stationary phases with different selectivities and analyzed using mass spectrometry. These methods are discussed below and results are presented with an emphasis on the relative concentrations and distribution of PAHs in the combustion samples.     

Distribution and Sources of Polycyclic Aromatic Hydrocarbons (PAHs) in Surface Sediments from the Northern Part of the Persian Gulf (Hormuzgan Province)

Sediments from the intertidal areas of Hormuzgan province in northern part of Persian Gulf (Iran) were investigated for the levels and possible sources of 15 polycyclic aromatic hydrocarbons (PAHs). Samples of sediments were collected from twelve sampling sites and analyzed for PAHs by gas chromatography–mass spectrometry (GC-MS). The results showed that the total concentrations of PAHs ranged from 765 to 1898 ng/g dry weight. Composition pattern in the sediment samples from 12 sampling sites was dominated by 4-ring PAH compounds. Molecular indices based on ratios of PAH concentrations were used to differentiate PAHs from pyrolitic, petrogenic and mixed origins. The results of study suggested that the main sources of PAHs in the sediment were mixed with pyrolitic and petrogenic inputs. According to the US sediments quality guidelines (SQGs) (ERL/ERM) sediments of the mentioned region did not show any ecotoxicological risk for benthic organisms.     

卷烟烟气中多环芳烃的同时测定

在优化卷烟烟气试样前处理技术的基础上,确定了6种多环芳烃分离的最佳条件和测定的最佳荧光激发、发射波长,并进行波长程序编程,采用高效液相色谱编程荧光法（HPLC-FLD）建立了一种同时测定卷烟烟气中6种多环芳烃的分析方法。各多环芳烃在所测定的含量范围内有良好的线性关系,方法的最低检出限可达到0.4 ng/mL,回收率均在87%以上。并利用该方法对国产卷烟样品进行了分析。     

Artefacts in semivolatile organic compound sampling with polyurethane foam substrates in high volume cascade impactors

Polyurethane foam (PUF) is known to sorb gas-phase semivolatile organic compounds (SVOCs) from ambient air and is used routinely in conventional high volume filter-sorbent sampling of such pollutants. PUF rings have also been employed as impaction substrates in a high volume cascade impactor (HVCI) used as a sampler for the evaluation of particle toxicity. Though nonvolatile particles (e.g., trace metals, inorganic ions) have been the primary focus, the sampler has also been used to measure particulate SVOC concentrations in ambient air. The aim of this work is to investigate the validity of the latter approach. The results of three sets of experiments conducted in Canada and Denmark are reported herein. Model compounds included native and deuterated polycyclic aromatic hydrocarbons (PAHs). The experiments demonstrated that HVCI PUF substrates sorb gas-phase PAH compounds and that the sorbed mass is subject to mobilization through and out of the sampler. Particulate concentrations of low molecular weight and volatile PAHs are therefore prone to overestimation in samples that have been analyzed after extraction of whole PUF substrates. Sonication of collected particles in water before solvent extraction is effective at dislodging them from the PUF but also acts to redistribute their originally particulate PAH mass back to the PUF and to the sonication water. As a result, the PAH content of particles measured after sonication and subsequent filtration does not accurately represent their true values. These artefacts affect not only measured PAH concentrations but also the results of toxicological assays that are conducted to test the characteristics of particles collected using HVCI PUF samplers.     

PAHs in Indoor and Outdoor Air from Decentralized Heating Energy Production: Comparison of Active and Passive Sampling

Spatial and temporal variation of vapor- and particle-phase polycyclic aromatic hydrocarbons (PAHs) was determined in six urban and sub-urban locations in Kaunas, Lithuania during heating and non heating seasons. Two different sampling methodologies were used: passive (based on semipermeable membrane device, SPMD) and active (based on collection on filter and sorption). Sixteen priority PAHs as well as methylated PAHs were quantified in the collected samples. The sampled total amount of 16 PAHs investigated in SPMDs ranged from 10–138 ng/day outdoors, from 5–59 ng/day indoors during the winter sampling campaign. In summer these amounts varied from 11–19 ng/day outdoors and from 19–27 ng/day indoors. The total concentrations of vapor and particle-phase PAH in winter in actively taken samples varied from 49–286 ng/m³ outdoors and from 28–83 ng/m³ indoors. Seasonal differences as well as the influence of the fuel burning for domestic heating purposes on the PAH concentration outdoors were well reflected by the data obtained using the SPMD methodology.     

WHERE ARE THE LIMITS OF THE GAS-PHASE FLUORESCENCE ON THE POLYCYCLIC AROMATIC COMPOUND ANALYSIS?

The aim of this work has been centered on the development of a detection system which could be useful to determine polycyclic aromatic hydrocarbon (PAH) emissions in power generation processes where PAHs are released to the atmosphere in the gas phase. In this way, a suitable sensor based on gas phase fluorescence spectroscopy was designed to facilitate the PAH analysis, avoiding previous steps necessary to determine liquid samples such as extraction, concentration, and cleaning. This gas cell was applied for two experimental installations at laboratory scale. One of them was used to determine adsorption capacities and breakthrough curves of PAH binary mixtures and the other installation allowed the separation of PAH mixtures by using, previous to the gas phase fluorescence spectroscopy, a packed column.     

THE FATE AND BEHAVIOR OF POLYCYCLIC AROMATIC HYDROCARBONS (PAHS) THROUGH FEEDING AND EXCRETION OF ANNELIDS

The concentration of polycyclic aromatic hydrocarbons (PAHs) in sediment and excrements of annelids was measured by gas chromatography-mass spectrometry (GC/MS) and the movement of PAHs in the tidal flat was investigated. The PAH concentrations ranged 4.4–80.4 and 61.2–286.9 μg/kg-dry for the excrement of Arenicola basiliensis and of Marphysa sanguinea, respectively; the former contained about 10 times as much PAHs as the sediment and the latter about 100 times. The difference in the PAH concentration between the two organisms was attributed to their feeding behavior; M. sanguinea intakes much more detritus containing PAHs than A. basiliensis. Moreover, after the excrement of M. sanguinea had stood on the sediment for 2 hours, the PAH concentrations decreased to half. The reduction of the PAHs may arise from chemical changes owing to microorganisms and/or enzymes in the excrement of M. sanguinea.     

Characterization of PM2.5-Bound Polycyclic Aromatic Hydrocarbons in the Ambient Air of Győr,Hungary

ABSTRACT

In Hungary, the nationwide monitoring of PM10-bound polycyclic aromatic hydrocarbons (PAHs) in ambient air is great importance for a number of reasons related to human health, the environment and compliance with European Union legislation. However, the measurement of PAH concentrations in PM2.5 aerosol fraction has not been carried out. Therefore, the concentration, distribution and sources of PM2.5-bound PAHs at different urban sites of Gy?r were investigated in a heating season. The total PAH concentrations (sum of 19 individual PAH compounds) ranged from 1.32 to 37.27 ng/m³ with the mean value of 10.54 ng/m³. The high molecular weight PAHs with 5 and 6 aromatic rings were the most abundant PAHs in PM2.5 aerosol samples, which averaged 82% of total PAHs. Using benzo(a)pyrene (BaP) equivalent approach on the concentration data of carcinogenic PAH species, BaP and indeno(1,2,3-cd)pyrene contributed the highest carcinogenic exposure equivalent (1.25 and 0.19 ng/m³ on average). However, the incremental lifetime cancer risk (ILCR) values for resident children and adults indicated low-potential cancer risk (ILCR < 10^?6). The source apportionment results reflected that the major sources of PAH compounds in the Gy?r atmosphere were fossil fuel combustion and vehicle emissions.     

Trace Enrichment and HPLC Analysis of PAHs in Edible Oils and Fat Products,using Liquid Chromatography on Electron Acceptor Stationary Phases in Connection with Reverse Phase and Fluorescence Detection

The determination of PAHs in lipids is beset with many difficulties, resulting from the low level of individual PAHs (μg/kg), the complexity of extraction and clean-up procedures required to isolate the PAHs from the oil or the food components. The purpose of this report is to describe a new method for multi-PAHs determination in lipidic matrixes. The clean-up step is realized by Donor Acceptor Complex Chromatography (DACC) with a tetrachlorophthalimidopropyl (TCPI) modified silica. Neutral lipids and other minor components, especially tocopherols which can interfere with PAH, are eluted with a hexane/methyltertiobutylether mixture. Then, PAH are eluted with pure methylene chloride and analyzed by gradient reversed phase HPLC in combination with wavelength programmed fluorescence detection. This method allows an easy and fast quantitative recovery of aromatic compounds.     

Personal Exposure of Children to Particle-Associated Polycyclic Aromatic Hydrocarbons in Tianjin,China

Polycyclic aromatic hydrocarbons (PAHs) associated with fine particles are harmful to human health, particularly to children, who are most vulnerable. To evaluate the respiratory exposure of children to particle-associated PAHs properly, personal air sampling near breathing zone of 36 schoolchildren were conducted in Tianjin, China. Sixteen priority PAHs designated by the United States Environmental Protection Agency were measured using GC-MS. The average concentrations of personal exposure to ∑₁₆PAH were 27.31 ± 3.91 ng/m³ in summer and 58.18 ± 24.68 ng/m³ in winter. Moreover, PAH profiles were studied and the results showed NAP, BbF, and IPY were the most abundant PAHs. Five rings PAH species made up the largest proportion, accounting for 25.7% in summer and 32.6% in winter. Diagnostic ratios and principal component analysis indicated combustion activities were the major source for children exposure to particle-associated PAHs in this study. According to the risk assessment results, the inhalation exposure risk for children were higher than the acceptable risk level of 10–⁶, indicating the health issues of children should be paid more attention. On the basis of sensitivity analysis results, further research should be done to improve the inhalation cancer slope factor of BaP and the concentration distribution of PAHs in order to improve the accuracy of the health risk assessment.     

Comparison of BEA, USY and ZSM-5 for the quantitative extraction of polycyclic aromatic hydrocarbons from water samples

The physicochemical properties of three commercial zeolites - namely BEA, USY and ZSM-5 - are compared for the water removal of 15 PAHs included in the US EPA priority pollutants list. The best percentages of extraction were obtained with BEA and varied from 85.2 ± 1.7% (benzo[g,h,i]perylene) to 99.6 ± 1.1% (pyrene). The correlation of physicochemical properties to the percentages of extraction suggests that the predominant factor for a successful extracting performance is the adsorption of PAHs to the external surface of the extracting material. This process is facilitated by relatively large total pore volumes, large average pore diameters and a homogeneous distribution of Lewis acid sites. The presence of the latter enhances extraction performance via π-electron interactions with the aromatic rings of the PAH.     

POLYCYCLIC AROMATIC HYDROCARBONS OF DIESEL AND GASOLINE EXHAUST AND DNA ADDUCT DETECTION IN CALF THYMUS DNA AND LYMPHOCYTE DNA OF WORKERS EXPOSED TO DIESEL EXHAUST

Particles present in urban air pollution are mainly derived from diesel- and gasoline-fueled vehicles. Exhaust emission is able to cause several health effects in humans including mutagenicity and carcinogenicity. Polycyclic aromatic hydrocarbons (PAHs) were measured in diesel and gasoline particulate extracts and DNA binding to CT DNA (±S9 and ±XO) was investigated. A large difference in content of 14 PAHs in diesel and gasoline extracts was observed, showing higher concentration of 14 PAHs, 6 carcinogenic PAHs, benzo[a]pyrene (B[a]P) in diesel than in gasoline extracts. Selected PAH standards of B[a]P, benzo[c]fluoranthene (B[c]F), and 3-nitrobenzanthrone (NBA) were used in ³²P-postlabeling/polyacrylamide gel electrophoresis (PAGE) technique to identify CT DNA adducts formed by diesel particulate extracts. CT DNA adduct formation was higher for diesel extracts in comparison with gasoline extracts; however, no clear origin of DNA adducts derived from B[c]F-, 3-NBA-, B[a]P was detected. ³²P-postlabeling/PAGE was a useful assay for analyzing and identifying PAH-DNA adducts. Occupational exposure to particulate and volatile PAH concentrations were evaluated using personal air samples and lymphocyte DNA adducts as markers of exposure. Overall air PAH concentrations were low in all eight workplaces, consisting of 97% of vapor phase compounds. DNA adducts analyzed by ³²P-postlabeling assay were compared between the butanol and nuclease P1 enrichment procedures. Only in winter samples of exposed workers, butanol extraction revealed significantly higher adduct levels in comparison with those of control persons. No differences in adduct levels between exposed and control persons in summer were detected by using either butanol extraction or nuclease P1 treatment. Total concentrations of particulate and volatile PAHs measured in eight workplaces in winter showed a significant correlation with total DNA adducts analyzed in workers' lymphocytes (r = 0.852N = 8, p = .007).     

Revealing the Origin of Polycyclic Aromatic Hydrocarbons in an Urban Snowpack

Polyciclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants in urban atmosphere. Several PAHs are known carcinogens or are the precursors to carcinogenic daughter compounds. Understanding the contributions of various PAH emission sources is critical to appropriately managing PAH levels in the environment. The sources of PAHs to urban snowpack in Shelekhov city, Eastern Siberia, characterized by extremely high levels of PAH accumulation in snow were determined by using end-member mixing approach. The best potential to distinguish PAH emission sources is exhibited by ratios of PAH pairs of the principal mass 228, 252, and 276. The ratios of PAH pairs were used as tracers of end-member PAH sources. The contributions of sources were calculated using systems of linear equations. The results obtained using ratios of PAH pairs were compared with those obtained using molecular diagnostic ratios. It was shown that the results obtained using diagnostic ratios as tracers are less reliable than the results obtained using the ratios of the sums of PAHs.     

Thermodynamic Behavior of Stable Carbon Isotopic Compositions of Individual Polycyclic Aromatic Hydrocarbons Derived from Automobiles

Concentrations, molecular compositions, and compound-specific stable carbon isotopic compositions ( i 13 C) of polycyclic aromatic hydrocarbons (PAHs) in gasoline exhaust particles (GEPs) and diesel exhaust particles (DEPs) were investigated in this study. i 13 C of PAHs in GEPs ranged from m 13.3 to m 26.8, and that in DEPs ranged from m 21.7 to m 26.3. The interspecies i 13 C variations in each sample were 5.3 - 2.2 in GEPs and 2.6 - 1.3 in DEPs. PAHs in GEPs show larger interspecies i 13 C variation than those in DEPs; hence, a degree of carbon isotopic fractionation during the conversion from fuel to PAH seems to be larger in gasoline engines than that in diesel engines. Pyrene series PAHs, which consist of only hexagonal rings, in almost all GEP samples show strong negative correlation between the H/C ratio and i 13 C whereas fluoranthene series PAHs, which contain a pentagonal ring, show less systematic isotopic behavior in GEP samples. A kinetic isotope effect in thermal cracking of organic macromolecules may be minor for PAH formation in vehicle engines. We suggest that the isotopic trend of pyrene series in GEPs can be explained by a thermodynamic isotope effect, and that disturbance from isotopic equilibrium may cause a weak correlation between the isotopic behavior and the H/C ratio among the interspecies PAHs.     

Effects of air/fuel combustion ratio on the polycyclic aromatic hydrocarbon content of carbonaceous soots from selected fuels

Patterns of polycyclic aromatic hydrocarbon (PAH) content were observed from GC/MS analysis of the extracts of soots at various air/fuel combustion ratios of three commonly used fuels: n-hexane, JP-8 (Jet fuel), and diesel. With increasing air/fuel ratio, from a simple diffusion flame up to an air/fuel ratio of 3.94, there is a significant loss of high molecular weight PAHs and an increasing abundance of oxidized lower molecular weight aromatics. The formation of high molecular weight PAHs is favored for JP-8 and diesel fuels at higher air/fuel combustion ratios than is the case with n-hexane, probably due to the aromatic content in JP-8 and diesel fuels acting as centers for large aromatic and soot nucleation. The efficiency and reproducibility of two techniques, Soxhlet and supercritical fluid extraction (SFE), used for extraction of PAHs from soot were compared. Electron paramagnetic resonance (EPR) measurements were performed on the soot both before and after supercritical fluid and Soxhlet extraction, and a substantial decrease in the spin density of soot following extraction indicates that extractable molecules are associated with 40–50% of the unpaired electrons in soot. This analysis generally supports trends observed in our earlier work for surface oxidation, surface area, unpaired electron spin density, hydration, and ozone oxidation.     

A study of interactions between soil fractions and PAH compounds in thermal desorption of contaminated soils

The interactions between three polynuclear aromatic hydrocarbons (PAHs), namely fluorene, naphthalene and anthracene, and three fractions of a soil, namely fulvic acid (FA), humic acid (HA) and humin/inorganic fractions, were studied experimentally. Prepared PAH + soil fraction binary mixtures, with PAH concentrations ranging over 0.8–7 mass%, were tested using a differential scanning calorimeter (DSC) over a temperature range of 20?390°C. The DSC thermograms for the PAH + HA mixtures showed distinctly different characteristics compared to mixtures with the other two soil fractions, where the endothermic peak for the vaporization of the PAH was absent. With the aid of vapour-liquid flash calculations, the lack of the boiling point peak is interpreted to be due to the liquid-phase miscibility of the PAHs and the HA fraction. Implications of the DSC results on the design and performance of the thermal desorption process are discussed.     

Liquid crystallinity in trimer oligomers isolated from petroleum and pyrene pitches

The first unsubstituted, monodisperse polycyclic aromatic hydrocarbon (PAH) to form a liquid crystalline phase (100% mesophase) has been isolated. With a molecular weight of 598 Da and consisting of only 14 aromatic rings, this pyrene trimer is also the lowest molecular weight (mol wt) PAH species for which the existence of liquid crystallinity has been reported. Multiple isomers of the pyrene trimer exist, providing the melting-point depression (mpt = 290 °C) necessary for the existence of a liquid phase and the possibility of mesophase formation. The trimer cut of M-50 pitch (mol wt = 645–890 Da; mpt = 330 °C) has also been isolated and was found to consist of ∼40% mesophase. This trimer is the lowest average mol wt carbonaceous pitch for which significant mesophase formation has been reported. Both trimers were isolated from their starting pitches via packed-column supercritical extraction, using toluene and N-methylpyrrolidone (NMP) mixtures as the extractive solvent. Mass spectrometry and UV–vis and fluorescence spectroscopy were used for molecular characterization. The results of this study indicate that for PAHs, the molecular weight for which liquid crystallinity occurs can be significantly reduced by creating PAH oligomers with lower polydispersity and increased monomer-unit homogeneity.     

THE LOADS OF PAHS IN WASTEWATER AND SEWAGE SLUDGE OF MUNICIPAL TREATMENT PLANT

Abstract

Sewage and sewage sludge from a municipal wastewater treatment plant were analyzed for 16 EPA-PAHs. This plant is a classic mechanical-biological treatment plant, consisting of activated sludge technology with additional chemical treatment for the removal of phosphorus compounds. The process of sewage sludge treatment is carried out in closed as well as open sludge digesters. Primary and mechanically thickened sludge are passed through the fermentation process. Digested sludge is dewatered on filter-press through addition of flocculent. The measurements were obtained to investigate the effect of different treatment stages on PAH content in wastewater and sewage sludge. The following wastewater samples were collected: crude ones and those after sand trap, primary sedimentation, biological treatment and secondary sedimentation. Sewage sludge samples were collected from: primary sludge, digested sludge and dewatered sludge. PAH load in influent, mechanically and biologically treated sewage, as well as in raw digested and dewatered sludge, were calculated. PAHs were extracted from wastewater and sludge samples, with cyclohexane, dichloromethane using an ultrasonic method. Gas chromatograph equipped with mass spectrometry was used for qualitative and quantitative determination of PAHs. Mechanical and biological treatment proved the removal of 83–85% of PAHs from the influent. Despite this its daily PAH load introduced into the environment was high and reached 27–37% of PAH load in influent. In sewage sludge it was 46–70 g/d of PAHs (carcinogenic PAHs content 4–12%). In waste sludge (filter pressed sludge and sand from detrirer) PAH total load reached 42–68 g/d with (10–17% of carcinogenic PAHs).