Light Polycyclic Aromatic Hydrocarbons Research Articles

Bioadsorption of crude petroleum oil from seawater using the marine alga Hormophysa triquetra mediated silver nanoparticles

The biosynthesis of silver nanoparticles, both economically and environmentally advantageous, uses algae extracts. In the current work, we extracted the marine brown alga Hormophysa triquetra (C. Agardh) kützing and used it to make silver nanoparticles (HAgNPs) which are characterized via UV–visible spectrophotometers, Transmission Electron Microscopy (TEM), Zeta potential, and FTIR then used them in the bio adsorption of crude petroleum oil from seawater, comparing them with H. triquetra aqueous extract. UV scan of the phycosynthesized silver nanoparticles achieved the highest absorption at 369 nm. TEM showed that the synthesized HAgNPs occur with smooth, spherical, and semispherical forms with sizes ranging from 12.04 to 20.67 nm, zeta potential illustrated that HAgNPs were charged with −22.1, The H. triquetra aqueous extract's FTIR examination identified several active groups like – OH, –C=C–, NO, –CH, CCl, –C ≡ C–H: CH which are responsible for the bioadsorption of crude petroleum oil. When extracting crude petroleum oil from seawater, HAgNPs worked better than its aqueous extract. The maximum removal % for light n-alkanes (Ln-alk), heavy n-alkanes (Hn-alk), and PAHs were 70.4 %, 71.63 %, and 75.38 % respectively for H. triquetra aqueous extract with adsorption capacity 889, 511, 273 μg/g at salinity 36 % and pH 5, while in case of HAgNPs the results were 75.81 %, 77.15 %, and 80.56 %, respectively with adsorption capacity 957, 550, 292 μg/g at the same salinity and pH.

Diffusion coefficients of polycyclic aromatic hydrocarbons in supercritical carbon dioxide: A molecular dynamics simulation study

Supercritical carbon dioxide (SC-CO2) extraction technology is an effective way to deal with soil contamination problems. Among them, polycyclic aromatic hydrocarbons (PAHs) are one of the main pollutants in soil. Studying the diffusion coefficients of PAHs in SC-CO2 can help us better understand the mass transfer characteristics during the SC-CO2 extraction process. Molecular dynamics simulation was applied in this work to study the diffusion behavior of PAHs in the SC-CO2 environment. Under different SC-CO2 thermodynamic states (temperature: 313–373 K, pressure: 10–30 MPa) and molecule sizes, the diffusion coefficients of PAHs were calculated. The trend of the interaction energy between PAHs and SC-CO2 molecules as temperature, pressure, and molecule size changed was also investigated. The findings demonstrated that compared to heavy PAHs, light PAHs had a higher diffusion coefficient in SC-CO2. Changes in the system’s temperature and pressure have an important effect on the diffusion coefficients of PAHs in SC-CO2. The high-temperature and low-pressure conditions had a promoting effect on the diffusion behavior of PAHs molecules. The van der Waals energy accounts for the largest proportion of the intermolecular interaction energy, which was about 80 %. It can be concluded that the van der Waals interaction energy played an important impact on the diffusion process of PAHs molecules in SC-CO2.

Molecular dynamics simulation of polycyclic aromatic hydrocarbons solvation behavior in supercritical carbon dioxide under different pressure and temperature

In this work, the solvation behavior of polycyclic aromatic hydrocarbons (PAHs) in supercritical carbon dioxide (sCO2) was investigated by molecular dynamics simulation. The effects of changing temperature and pressure on the solvation behavior were studied. In addition, the value of the interaction binding energy of PAHs-sCO2 and the radial distribution function at various conditions was calculated to study the solvation mechanism. The simulation results showed that high pressure and low temperature can promote the solvation of PAHs in sCO2. However, the effect of pressure change on the solvation behavior was considerably less noticeable than that of temperature change. Furthermore, the solvation of heavy PAHs appeared to be harder than light PAHs. The interaction energy between sCO2 and PAHs decreased as temperature increased, while increased as pressure increased. Moreover, the interaction mechanism analysis found that the van der Waals interaction force dominated the interaction force between sCO2 and PAHs molecules.

The effect of biotransformation of sewage sludge- and willow-derived biochars by horseradish peroxidase on total and freely dissolved polycyclic aromatic hydrocarbon content

This study analyzed the effect of enzymatic aging (horseradish peroxidase) of biochars on their content of solvent extractable (Ctot) and freely dissolved (Cfree) polycyclic aromatic hydrocarbons (PAHs). Physicochemical properties and phytotoxicity of pristine and aged biochars were also compared. The study used biochars obtained at 500 or 700 °C from sewage sludges (SSLs) or willow. Compared to SSL-derived biochars, willow-derived biochars were more susceptible to enzymatic oxidation. Aging increased the specific surface area and pore volume of most SSL-derived biochars. An opposite direction, however, was found in the willow-derived biochars. Low-temperature biochars, regardless of their feedstock, underwent physical changes, such as removal of labile ash components or degradation of aromatic structures. The enzyme caused an increase in the content of Ctot light PAHs in biochars (by 34–3402 %) and heavy PAHs (≥4 rings) in the low-temperature SSL-derived biochars (by 46–713 %). In turn, the content of Cfree PAHs decreased in aged SSL-derived biochars (by 32–100 %). In the willow-derived biochars the bioavailability of acenaphthene increased (by 337–669 %), while the immobilization degree of some PAHs was lower (25–70 %) compared to the SSL-derived biochars (32–83 %). Nevertheless, aging positively affected the ecotoxicological properties of all biochars by increasing their stimulation effects or removing their phytotoxic effects on both Lepidium sativum seed germination and root growth. Significant relationships between the changes in Cfree PAH content, pH and salinity of SSL-derived biochars and seed germination/root growth inhibition were found. The study demonstrates that the risk associated with application of SSL-derived biochars, regardless of the type of SSL and pyrolysis temperature, can be lower in terms of Cfree PAHs than in the case of willow-derived biochars. Regarding to Ctot PAHs, high-temperature SSL-derived biochars are safer than low-temperature ones. In the case of application of high-temperature SSL-derived biochars, these with moderate alkalinity and salinity will not bring risks for plants.

Risk assessment of polycyclic aromatic hydrocarbons and organochlorine pesticides in olive oil in Jordan

Many organochlorine pesticides (OCPs) and polycyclic aromatic hydrocarbons (PAHs) pose risks to human health; so, their levels in foods should be constantly monitored. In the present work, the potential health risks of 21 OCPs residues and 16 carcinogenic PAHs in Jordanian olive oil were evaluated. A total of 27 olive oil samples were obtained from nine olive mills in Jordan. The levels of PAHs and OCPs were evaluated by gas chromatography coupled with mass spectrometry detector. Among the studied pesticides, only 4,4-Dichlorodiphenyldichloroethylen (4,4-DDE) was found in the tested samples. The estimated average dietary intake (EADI) and hazard risk index (HRI) were then assessed for the 4,4-DDE. The estimated HRI value of 4,4-DDE was less than 1, thus indicating no health risk to consumers. Regarding PAHs, the average concentration of 16 PAHs in the tested olive oil was 36.5 µg/kg. Health risks due to PAH contamination were estimated by determining the dietary daily intake (DDI) and toxic equivalent quotient (TEQ). The values ranged from 0.139 × 10-2 to 7.70 × 10-2 and 0.01 to 0.57 µg/kg for DDI and TEQ, respectively. Light PAHs were predominant in the samples, while no heavy PAHs were detected. The incremental lifetime cancer risk (ILCR) was estimated, and the values ranged from 0.1 × 10-7 to 5.62 × 10-7, and none of the olive oil samples exceeded the limit value of 10-6, thus indicating insignificant potential risk.

Scientists find complex aromatic molecules in young, distant galaxy

Astronomers have detected polycyclic aromatic hydrocarbons (PAHs) in a galaxy observed as it was less than 1.5 billion years after the Big Bang, according to a new report ( Nature 2023, DOI: 10.1038/s41586-023-05998-6 ). The findings demonstrate the James Webb Space Telescope’s (JWST) prowess for probing chemistry in deep time. While earthbound chemists might find these complex organic molecules in soot or smog, astronomers seek out PAHs in space to guide them toward newborn stars. When stars first form, they blast out intense ultraviolet (UV) radiation. That UV light photoactivates PAHs, which emit infrared (IR) radiation in turn. So when IR telescopes spot emissions of PAHs, it’s likely because a blazing young star lit them up, says Justin Spilker, an astrophysicist at Texas A&M University. That’s what the Spitzer Space Telescope and others have observed in nearby galaxies, but limited instrument sensitivity has prevented astronomers from glimpsing PAHs in our

Comparison of generic Tenax and specialized PAH tubes for monitoring polycyclic aromatic hydrocarbons in the ambient air

The thermal desorption (TD) technique has potential advantages for monitoring polycyclic aromatic hydrocarbons (PAHs) in the air, e.g., no need for sample preparation. This study aims to compare the performance of two types of TD tubes: the generic Tenax TA tube and a proprietary PAH tube specifically designed for PAH sampling. Full calibrations were performed on a TD-gas chromatography/mass spectrometry (GC/MS) system for 16 priority PAHs. Co-located field samples were collected with two tubes at a flow rate of 200 mL/min for 24 h in eight rounds. In the laboratory, blank Tenax and PAH tubes had trace-level PAHs ranging from 0 to 0.35 ng/tube and 0−0.83 ng/tube, respectively, after 2-hr conditioning at 330 °C. The calibration with Tenax tubes showed an average precision of 7.5%, R2 from 0.9959 to 1.0000, and method detection limits (MDLs) from 0.056 to 3.64 ng/m3. The calibration of PAH tubes showed an average precision of 7.5%, R2 from 0.9945 to 1.0000, and MDLs from 0.065 to 5.91 ng/m3. In the field, blank Tenax and PAH tubes had trace PAH levels of 0.01–0.34 ng/tube and 0.01−0.42 ng/tube, respectively. Both tubes had negligible breakthroughs (<4%) and good precisions (<20%). Co-located Tenax and PAH tubes displayed a good agreement for light PAHs (differences mostly <30%) but high uncertainty for heavy PAHs (difference 35−70%). Both tubes are applicable for PAH monitoring, but the proprietary PAH tube does not outperform the generic Tenax TA tube. More work is still needed to improve the sensitivity of TD methods for heavy PAHs, e.g., selecting appropriate sorbents and adopting advanced instruments.

Identifying the contributions of root and foliage gaseous/particle uptakes to indoor plants for phthalates, OPFRs and PAHs

Understanding the uptake pathways of organic chemicals in plants can help us use plants as biosentinels for human exposure, and as remediation tools for contaminated sites. Herein, we investigated the relative contributions of root and foliar (gas and particle) uptake pathways to indoor ornamental plants for phthalates (PAEs), organophosphorus flame retardants (OPFRs), and polycyclic aromatic hydrocarbons (PAHs). We looked at different kinds of indoor ornamental plants via pot and hydroponic control experiments, comparing the levels between their leaves and indoor air gaseous and particle phases, floor dust, and window film. Contributions of soil and foliage uptakes were calculated based on chemical concentrations in leaves of hydroponic and soil cultured plants and their mass uptake rates. Across all compounds, the contributions of root uptake to the chemicals in soil cultured plants ranged from 47.5 % to 88.5 %. We used binary first-order mass conservation equations to calculate the contributions of foliage uptake via gaseous and particle phases to the chemicals with similar Kow in plant leaves. Foliar uptake of PAEs occurred mainly via particle adsorption, for light PAHs via gaseous absorption, and for OPFRs via both particle and gaseous uptakes. Negative correlations between chemicals' foliage uptake ratios and their Kow and Koa values suggest that foliage uptake may be influenced by both chemical hydrophilicity and lipophilicity.

Polycyclic Aromatic Hydrocarbons in Popcorn Corn Varieties and Popcorns

Popping corn is a widespread activity and popcorns are one of the most consumed snacks in the world. As popcorn corn is exposed to environmental conditions and agrotechnical measures in the field, polycyclic aromatic hydrocarbons (PAHs) can end up in corn kernels. Since popcorns are popped at higher temperatures, ca. 180 °C, it is reasonable to assume that PAHs can be found in popcorns. The objective of this paper was to preliminarily determine and quantify the incidence of various PAHs in different popcorn varieties and popcorns popped from them, during two consecutive years. PAHs were determined by using GC-MS. Popcorn corn contained only light PAHs, naphthalene (Nap), acenaphthene (Ane), and fluorene (Fln). However, popped popcorns contained heavier PAHs, such as benz[a]anthracene (BaA), chrysene (Chry), and benzo[a]pyrene (BaP) whose ∑PAH4 was 8.39 µg/kg in sample 1 in 2020. The results indicate that popcorns can be a significant source of PAHs and further studies should be conducted. This is concerning since popcorns are favored snacks in all age groups, including children.

Fire-Induced Alterations of Soil Properties in Albic Podzols Developed under Pine Forests (Middle Taiga, Krasnoyarsky Kray)

Fires are one of the most widespread factors of changes in the ecosystems of boreal forests. The paper presents the results of a study of the morphological and physicochemical properties and soil organic matter (SOM) of Albic Podzols under pine forests (Pinus sylvestris L.) of the middle taiga zone of Siberia (Krasnoyrsky kray) with various time passed after a surface fire (from 1 to 121 years ago). The influence of forest fires in the early years on the chemical properties of Albic Podzols includes a decrease in acidity, a decrease in the content of water-soluble compounds of carbon and nitrogen and an increase in the content of light polycyclic aromatic hydrocarbons (PAHs) in organic and upper mineral horizons. Podzols of pine forests that were affected by fires more than forty-five years ago are close to manure forest soils according to most physical and chemical properties. Significant correlations were found between the thickness (r = 0.75, p &lt; 0.05), the moisture content (r = 0.90, p &lt; 0.05) of organic horizons and the content of ∑PAHs in the organic horizon (r = −0.71, p &lt; 0.05) with the time elapsed after the fire (i.e., from 1 to 121 years). The index of the age of pyrogenic activity (IPA) calculated as the ratio of ∑ PAHs content in the organic horizon to ∑ PAHs at the upper mineral horizon is significantly higher in forests affected by fires from 1 to 23 years than for plots with «older» fires (45–121 years). Thus, the article presents the conserved and most changing factors under the impact of fires in the boreal forests of Russia.

Effect of Extract of Perilla Leaves on the Quality Characteristics and Polycyclic Aromatic Hydrocarbons of Charcoal Barbecued Pork Patty.

This study aimed to investigate the effect of ethanolic extracts from perilla leaves (PLE) on the quality attributes and polycyclic aromatic hydrocarbons (PAHs) in charcoal-barbecued pork patties. The PLE addition and doneness had no significant effect on the pH of pork patties (p>0.05). Regardless of the concentration, the PLE significantly lower malondialdehyde concentrations and reduced the CIE L*, CIE a*, and CIE b* when compared to control. The addition of 0.2% of PLE did not adversely affect the organoleptic properties of doneness of medium and well-done pork patties. Addition of PLE at 0.4% to medium-cooked pork patties had stronger suppressing effect on the formation of light PAHs compare to control (p<0.05), also adding it to well-done pork patties had the lowest concentration of 4 PAHs and 8 PAHs, and a total of 16 PAHs (p<0.05). Therefore, PLE at 0.4% can be used for suppressing the formation of PAHs and lipid oxidation in well-cooked pork patty.

Characterizing the efficiency of low-cost LED lights for conducting laboratory studies to investigate polycyclic aromatic hydrocarbon photodegradation processes

Polycyclic aromatic hydrocarbons (PAHs) are common contaminants ubiquitously present in various waste products such as biosolids (e.g. wastewater sludges), oil spill residues (e.g. tarballs), road asphalts, and combustion byproducts. In this study, the photodegradation of PAHs is investigated under natural sunlight (cloudy and sunny/clear weather conditions), and using two types of artificial LED light sources. This is the first study to investigate the relative efficiency of low-cost LED light sources for conducting laboratory-scale PAH photodegradation experiments and directly comparing the results against those obtained using natural sunlight. Two types of LED light sources are investigated in this study: a light source with a full-spectrum range (380 nm–780 nm) that can cover the broad wavelength range of solar light reaching the Earth's surface, and a light source with a UV-A range (365 nm) that covers the UV range of the solar spectrum reaching the Earth's surface. The results show that the degradation of high molecular weight (HMW) PAHs is primarily due to photodegradation, and other lighter PAHs are degraded by both photodegradation and evaporation processes. HMW PAH photodegradation reactions follow the first-order degradation kinetics. The degradation rate constants of different PAHs are used to compare the relative efficiency of the light sources. The data show that the full-spectrum LED induced PAH photodegradation rates are similar to the natural sunlight induced rates. Furthermore, when the values of the rate constants are normalized to respective irradiance levels, the normalized rates for HMW PAH photodegradation under both full-spectrum LED light and natural sunlight are almost identical. However, the normalized photodegradation rate constants of HMW PAHs under the UV-A LED light are about two to three orders of magnitude higher than the sunlight as well as the full-spectrum-LED values. Therefore, the UV-A LED light is the optimal low-cost light source for studying PAH photodegradation processes under laboratory conditions.

Simultaneous in-situ tar abatement and H2-enriched syngas production via heterogeneous doping of LaFeO3 during chemical looping gasification of microalgae

Chemical looping gasification (CLG) is an emerging environment-friendly technology for efficient and clean utilization of biomass, in which oxygen carrier (OC) is one of the key issues concerning the overall performance. As a rising-star material, perovskite with a tunable crystal structure shows great potential in syngas enrichment and tar decomposition during the CLG of biomass. In this study, the newly-developed LaNi0.5Fe0.5O3 (LN5F5) and La0.3Ba0.7FeO3 (L3B7F) perovskites through heterogeneous doping of LaFeO3 (LF) were evaluated as oxygen carriers with the purpose of simultaneous tar abatement and H2-enriched syngas production from microalgae. Silica sand (SS) and iron ore (IO) were used for comparison. Results showed that the CLG performance order of several materials was L3B7F > LN5F5 > LF > IO > SS at an oxygen carrier to biomass ratio (O/B) of 0.4, water injection rate of 0.3 mL/min and gasification temperature of 800 °C. The heterogeneous doping obviously improved the cyclic stability of perovskite during redox tests. In addition, possible tar conversion routes over L3B7F oxygen carrier were proposed. Results implied that heavy PAHs (4 rings or more) were first converted to light PAHs (1–3 rings) and n-hydrocarbon, which were finally transformed into micromolecular gases. The outstanding performance of L3B7F in microalgae CLG can be ascribed to the formation of oxygen vacancies and high-valence Fe4+ stimulated by the introduction of Ba2+, which were demonstrated by the XRD, H2-TPR and XPS results. These results evidence that the heterogeneous doped L3B7F is a good alternative for improving biomass availability in the CLG process.

Air Mapping of Polycyclic Aromatic Hydrocarbons and Their Uptake by Crops in the Urban Area of Nice, France.

Urban gardening is becoming increasingly popular. Air pollution, which is a major concern in cities might, however, threaten food safety and thus must be assessed. Health risks arise particularly from toxic persistent organic pollutants such as Polycyclic Aromatic Hydrocarbons (PAHs) which are formed by incomplete combustion. A first assessment of crop contamination in two different atmospheric environments in the urban area of Nice reveals a predominance of light PAHs. These pollutants present in the gaseous phase, seem to bioaccumulate while heavy PAHs are absent in vegetation. By understanding the PAH sources and their behavior in the atmosphere but also by analyzing the spatial and temporal data since the European directive in 2004, a link between concentrations found in vegetables grown in experimental gardens and PAH cadastral emission data is presented. The first results could be used as a possible guidance for urban agriculture.

Polycyclic Aromatic Hydrocarbons in Soil at Different Depths under a Long-Term Experiment Depending on Fertilization.

The aim of this study was to assess the effect of long-term fertilization with manure and mineral fertilizers on the content and distribution of selected polycyclic aromatic hydrocarbons (PAHs)—the content of a sum of 16 polycyclic aromatic hydrocarbons, light and heavy PAHs in two soil layers (0–30 cm and 30–60 cm). The material for the study was composed of soil samples collected from the sixth rotation in a long-term, controlled field experiment, conducted in Bałcyny since 1986. The content of 16 polycyclic aromatic hydrocarbons was determined on a gas chromatographer coupled with an FID detector. In order to evaluate the significance of differences between the mean effects on the tested characteristics, a non-parametric Mann–Whitney U test for two independent samples was applied. A higher content of the sum (16) of PAHs was found in the 0–30 cm than in the 30–60 cm soil layer. The research results also demonstrated a higher content of the sum of light PAHs in the 30–60 cm than in the 0–30 cm soil layer. The content of heavy PAHs, in turn, was significantly higher in the upper than in the deeper soil layer. This dependence appeared in both the soil fertilized with manure and soil nourished only with mineral fertilizers.

Ecological risk assessment of metal and hydrocarbon pollution in sediments from an urban tropical estuary: Tijuca lagoon (Rio de Janeiro, Brazil).

Urban tropical lagoons are often impacted by eutrophication, metal, and polycyclic aromatic hydrocarbon (PAH) contamination, but the toxicity of their bottom sediments is still poorly investigated in South America. Aiming to contribute to filling this gap, a sediment quality assessment was conducted in the Tijuca Lagoon (Rio de Janeiro, Brazil) using different lines of evidence (LOEs) including sediment characterization, determination of metals and PAHs, and acute toxicity testing with burrowing amphipods (Tiburonella viscana). Mud and organic matter contents played a crucial role in contaminant distribution along the lagoon. The concentrations of PAH were generally low (mean ΣPAH = 795.42 ± 1146.2ng/g; n = 23), but a contamination hotspot of light PAH compounds was identified. Such PAHs were mainly pyrolytic, probably related to the deposition of atmospheric pollution, although petrogenic compounds also occur in the lagoon. The data indicated the occurrence of geochemical anomalies of Zn, Cu, Pb, and Hg (mean values = 176.9 ± 91.6, 45.1 ± 21.3, 35.2 ± 15.0, 0.1442 ± 0.0893mg/kg, respectively; n = 23), probably associated with industrial wastes, garbage deposition, urban runoff, and domestic sewage contributions. The mortality of T. viscana was significant for more than 85% of the samples (mean mortality = 70.3 ± 26.0%; n = 23), but it was not significantly correlated with PAH and metal concentrations. On the other side, domestic sewage contributions and eutrophication seem to play a relevant role in sediment toxicity. Actually, the toxicity observed in the tests seems to be due to the simultaneous influence of multiple toxicants and their combined effects on the organisms. Such stressors may include not only metals, PAH, and eutrophication but also chemicals not evaluated in this study, such as hormones, pharmaceuticals and personal care compounds, perfluorocompounds, detergents, and others.

Gas-particle partitioning of polycyclic aromatic hydrocarbons from oil combustion involving condensate, diesel and heavy oil

This study focuses on the gas-particle (G-P) partitioning of 16 polycyclic aromatic hydrocarbons (PAHs) from oil combustion, which is one of the important contributors of anthropogenic PAHs but has been rarely studied. The combustions of different types of oils involving ultra-light to heavy oils were investigated, and the PAH partitioning mechanism was determined by the widely used Junge-Pankow adsorption model, Koa absorption model, and dual sorption model, respectively. The results show that the source-specific diagnostic ratios of Ant/(Ant+Phe) are between 0.09 and 0.24, the estimated regression slopes of G-P partition coefficients (KP) of the total PAHs on their sub-cooled liquid vapor pressures (PLO) are in the range of − 0.34 to − 0.25, and the predicted fractions of PAHs in the particle phase (φ) by Koa absorption model are close to the measured values, while the log KPvalues of the LMW PAHs from the combustions of diesel and heavy oil are better represented by the dual sorption model. Our findings indicate that PAHs are derived from mixed sources that include the unburned original oil and combustion products, and the PAH partitioning mechanism is governed by the process of absorption into organic matter because of the unburned oil, but both adsorption and absorption exist simultaneously in the lighter PAHs from the combustions of heavier oils (i.e., diesel and heavy oil). Based on these findings, the understanding of the fate and transport of PAH emissions and the optimization of the emergency responses to accidents such as marine oil spills would be potentially improved.

Rapid Screening of 22 Polycyclic Aromatic Hydrocarbons Residues in Vegetable Oils by Gas Chromatography-Electrostatic Field Orbitrap High Resolution Mass Spectrometry.

A method for simultaneous determination of 22 polycyclic aromatic hydrocarbons (PAHs) residues in vegetable oils by gas chromatography-electrostatic field orbitrap high resolution mass spectrometry (Orbitrap GC-MS) was established. The samples were vortexed with acetonitrile, centrifuged at 8,000 r/min for 5 min, and frozen at −70°C for 10 min. The extracts of upper layer were poured out, dried with nitrogen at 40°C, redissolved in dichloromethane, and measured by Orbitrap GC-MS. The matrix interference in vegetable oil could be effectively removed by determining the accurate mass number of target compounds under the full scan mode. Six typical vegetable oil samples (soybean oil, sesame oil, peanut oil, olive oil, rapeseed oil, sunflower oil) were used for method validation. The calibration curve displayed good linearity in the range of 1–100 ng/mL, with correlation coefficients > 0.9950. The limits of detection (LODs) were in the range of 0.10–0.60 μg/kg, and the limits of quantification (LOQs) were in the range of 0.35–2.00 μg/kg. The average spiked recoveries of 22 PAHs in 6 matrices at 5, 50 and 100 μg/kg levels were 76.4–115.4%, and the average relative standard deviations (RSDs) were 1.8–10.8%. The results showed that 22 PAHs were detected in 6 types of 90 edible vegetable oil samples in the Chinese market by this method. Meanwhile, the abundance of light PAHs (LPAHs) was higher than that of heavy PAHs (HPAHs), and its relative contribution of LPAHs to the total PAHs was higher. All levels of BaP conformed to the Chinese requirement of upper limit, 10 μg/kg. However, 13.3 and 11.1% of the samples exceeded the maximum limits of BaP and PAH4 set by EU, 2 and 10 μg/kg, respectively. The total concentrations of 22 PAHs (defined as PAH22) varies greatly among different oil species, and the average PAH22 contents were listed in descending order as follows: peanut oil > sesame oil > olive oil > rapeseed oil > soybean oil > sunflower seed oil. The established method effectively avoided interference from large amounts of lipids and pigments. Therefore, the method is simple, sensitive and suitable for rapid screening and confirmation of PAHs in vegetable oil.

Trace-Level Determination of Polycyclic Aromatic Hydrocarbons in Dairy Products Available in Spanish Supermarkets by Semi-Automated Solid-Phase Extraction and Gas Chromatography-Mass Spectrometry Detection.

Polycyclic aromatic hydrocarbons (PAHs) have been classified as priority pollutants by the U.S. Environmental Protection Agency (EPA) and the European Commission on the grounds of their carcinogenic, mutagenic and teratogenic properties. Because of their ubiquity in industrial processes and the environment, PAHs can reach milk and dairy products and, eventually, humans. In this work, a new method was developed to detect and quantify sixteen of the EPA’s priority PAHs in commercial milk and dairy products. The method involves liquid–liquid extraction (LLE) followed by semi-automated solid-phase extraction (SPE) to clean up and preconcentrate the analytes prior their detection and quantification by gas chromatography–mass spectrometry (GC–MS). The proposed method provided high precision (relative standard deviation < 11.5%), recoveries of 80–107% and low detection limits (1–200 ng/kg). The method was applied to analyze 30 dairy products, the majority of which contained some PAH at concentrations from 7.1 to 1900 ng/kg. The most-detected analytes were the lighter PAHs (naphthalene, acenaphthylene, fluorene and phenanthrene). None of the samples, however, contained more than four PAHs.

Effect of biomedical waste co-feeding in the steam gasification of Indian palm kernel shell in fluidized bed gasifier

Gasification is the thermo-chemical process that converts biomass into producer gas which is used for various applications like heat production, electricity, and hydrocarbon synthesis. In this present work, the steam gasification of biomedical waste such as glucose plastic bottle, syringe, and Indian palm kernel shell is gasified in fluidized bed gasifier. The mixture of palm kernel shell co-feeding with biomedical waste such as 100% palm kernel shell (PKS), 25% biomedical waste (BMW), 50% biomedical waste, and 100% biomedical waste using olivine as a primary catalyst is used. The influences of co-feeding of biomedical waste with palm kernel shell on the gas yield, char yield, tar yield, carbon conversion efficiency, tar composition, and gas composition are investigated. The co-feeding of biomedical waste with palm kernel shell for steam/feedstock mass ratio of 1, the tar content is decreased from 53.56 to 3.6 gNm-3 and the char is reduced from 4.9 to 0.4 wt %. Heterocyclic, heavy polycyclic aromatic hydrocarbons and light aromatic compounds are reducing when compared to that of light polycyclic aromatic hydrocarbons at temperature 900°C. The value of carbon conversion efficiency also increases for palm kernel shell is 78.7% and for biomedical waste is 98% respectively. Hence, the scope of the present study is to optimize the process parameters for the taken feedstock with respect to our environmental condition with the help of lab scale reactors. Later scale up can be done to utilize the product for practical applications.