Concentrations Of Hydrocarbons Research Articles

Influence of Smoking and Paprika Spice on the Content of Polycyclic Aromatic Hydrocarbons (PAHs) in the Traditional Spanish Smoked Sausage ‘Botillo del Bierzo’

The content of polycyclic aromatic hydrocarbons (PAHs) in a traditional Spanish smoked sausage known as ‘Botillo del Bierzo’ was analysed. The determination and quantification of PAH4 (the sum of benzo[a]pyrene, benz[a]anthracene, benzo[b]-fluoranthene and chrysene) in the smoked sausage were performed using GC–MS. The results showed that smoking ‘Botillo del Bierzo’ for 24 h contributes very little to the increase in PAH levels in the product, with no significant differences (p < 0.05). The paprika used in the production of botillo also contributes to PAH content, depending on the paprika’s production process (smoked, low-smoked, mixed paprika (smoked + unsmoked or low-smoked + unsmoked), and unsmoked), with significant differences among them (p < 0.05). Using paprika with a lower PAH content (unsmoked or mixed) enables the production of ‘Botillo del Bierzo’, in accordance with Protected Geographical Indication specifications, with a lower PAH content while maintaining the organoleptic characteristics provided by the paprika. The contamination levels detected in ‘Botillo del Bierzo’ do not pose a risk to consumer health, as the benzo[a]pyrene and PAH4 values are well below the regulatory limits of 5 μg/kg and 30 μg/kg, respectively.

Plant-part chemical composition of essential oils of Crithmum maritimum L. from Montenegro

This paper reports the chemical constituents of essential oils from different organs of Crithmum maritimum L. collected at three localities in Montenegro (Bar, Budva and Herceg-Novi), thus covering the northern, central and southern parts of the national coastline. A total of 12 samples were isolated by hydrodistillation and analysed by gas chromatography–mass spectrometry method. The highest yield was observed in fruits, while rhizomes contained the lowest amount of essential oil. The high content of monoterpene hydrocarbons, such as limonene and γ-terpinene, characterised the samples from leaves, fruits, and flowers. Essential oils obtained from rhizomes were characterised by phenylpropanoids dillapiole and elemicin. Depending on the plant organ and locality, four different chemotypes can be distinguished. This is the very first report on essential oils of C. maritimum L. leaves, flowers, and fruits collected in Montenegro.

Implementation of an Improved 100 CMM Regenerative Thermal Oxidizer to Reduce VOCs Gas

In this paper, an improved 100 CMM regenerative thermal oxidizer (RTO) is implemented for low-emission combustion. The existing RTO system is a cylindrical drum structure that cyclically introduces and discharges VOC gas into and from the rotating disk, and which achieves excellent energy efficiency with a heat recovery rate of more than 95%. However, the drive shaft designed under the RTO combustion chamber increases wear around the rotating shaft due to the load of the combustion chamber and there is a problem that the untreated gas is simultaneously released through the outlet due to the channeling phenomenon of the combustion chamber and the drive shaft. In addition, the combustion chamber, used at a high temperature of 800 °C, may cause serious problems such as rotation stop or explosion due to pollutants, dust accumulation, and thermal expansion in the chamber. Particularly when treating VOCs harmful gasses, RTO performance may be degraded due to the burner’s non-uniform temperature control and unstable combustion function. To solve this problem, first, the design of the combustion chamber rotating plate driving device is improved. Second, when treating high concentration VOC gas, the design of combustion chamber considers a temperature increase of up to 920 °C or more. For this, the diameter of the gas burner is 125 mm and the outlet dimension is set to 650 mm × 650 mm to effectively discharge high-temperature waste heat. Third, the heat storage material in the combustion chamber is composed of a ceramic block with a thickness of 250 mm, and the outer diameter and height of the combustion chamber are set to, 2530 mm and 1875 mm, respectively, to optimize gas residence time and heat insulation thickness. Fourth, we supplement safe operation by applying the trip control algorithm of the programmable logic controller (PLC) panel for failure prediction of RTO and the Edge-IoT-based intelligent algorithm for this. Finally, we evaluate the economic performance of 100 CMM RTO by conducting empirical experiments to analyze changes in VOCs removal efficiency, nitrogen oxide emission concentration, and total hydrocarbon (THC) concentration through 10 CMM design and implementation.

Investigating Oil Entrance from Hendijan Oil Field in the Northwest of the Persian Gulf Using Chemical Fingerprinting.

Concerning the entrance of oil into the Persian Gulf due to the presence of oil fields in this ecosystem, a wide investigation was carried out in 2017 to evaluate the hydrocarbons source identification and chemical fingerprinting. To this end, surface sediments were collected from the Persian Gulf. In the laboratory, compounds (n-alkanes, PAHs, hopane and sterane) were then extracted with a Soxhlet system and two steps of chromatographic columns and analyzed using a GC-MS instrument. The results showed that the concentrations of the n-alkanes and Σ30 PAHs increased with a reduction in distance from hot spots. This suggests that high concentrations of hydrocarbons in the locations near the hot spots might be due to oil leakage, transportation of and exploration for oil, pipeline fractures and industrial activities. A positive relation between total organic matter (TOM) and hydrocarbons was observed. A common petrogenic hydrocarbon source was strongly implied in most places by the presence of unresolved compounds resolved (UCM), lower molecular weight/higher molecular weight (LMW/HMW) and carbon preference index (CPI) ratios < 1. Typical profiles of petrogenic PAHs with predominant alkyl substituted naphthalene and phenanthrene, various PAH ratios and multivariate analysis showed that PAHs were mainly derived from petrogenic sources. Simultaneous use of n-alkanes and PAHs in source identification can be effective to precisely specify the hydrocarbon sources in complicated mixture ecosystems. Furthermore, using multivariate analysis and chemical fingerprinting of n-alkanes, PAHs, hopanes and sterane confirmed that Hendijan crude oil may be the source of the sediment pollution in the study area.

An Assessment of the Performance and Emissions of an Otto Power Generator Group Operating with Wet Ethanol at a High Volumetric Compression Ratio

This work presents an experimental study of the performance and emissions of an internal combustion engine operating in the Otto cycle with a high volumetric compression ratio (17:1). The engine was initially fueled with the standard ethanol used in Brazil, with 7% distilled water (E93W07); we then studied the effects of using different ethanol-in-water mixtures, or ‘wet ethanol’, with 17%, 27%, 37%, and 47% distilled water concentrations. The tests were carried out with power loads of 5.0–25.0 kW at 5.0 kW intervals and with power loads of 27.5–35.0 kW at 2.5 kW intervals, whether by adding up the loads or by taking them away. The ignition timing was changed to evaluate each load imposed on the engine to avoid knocking. Specific fuel consumption (SFC), brake thermal efficiency (BTE), carbon dioxide emissions (CO2), carbon monoxide (CO), nitrogen oxides (NOx), and total hydrocarbon content (THC), as well as the internal pressure in the cylinder and the heat release rate, were measured, and the results are compared. The results show a reduction in CO and NOx and an increase in THC emissions. However, there were no significant changes in CO2 emissions when the distilled water percentage in ethanol increased. Regarding the brake thermal efficiency, it was observed that it remained approximately constant for all blends, with the same load being applied to the engine shaft, reaching a maximum value of 35%. The results obtained confirm the technical feasibility of operating an internal combustion engine in the Otto cycle with a high volumetric compression ratio using ethanol with up to 47% distilled water without significant loss of performance.

Influence of smoking method and anatomical location on the content of polycyclic aromatic hydrocarbons in Turopolje ham

In order to support a more sustainable breeding of the local Turopolje pig, the breed needs to be valorised through high added-value meat products, such as dry-cured and smoked Turopolje ham. To date, there are very few data on the quality and safety of Turopolje ham, including information on the content and distribution of potential contaminants such as polycyclic aromatic hydrocarbons (PAHs) from smoke. Hence, the aim of this study was to investigate the influence of smoking method (traditional or industrial) and anatomical site (M. biceps femoris - BF or M. semimembranosus - SM) on the content of PAHs in Turopolje ham. All hams (n=15) were produced the same way, differing only in smoking procedures; a traditional way above the firebox (group TRAD, n=5) or in the smoking chamber (group IND A - standard smoking, n=5 or B – 50 % reduced smoking, n=5). PAHs content (μg/kg) was determined and quantified by high-performance liquid chromatography with fluorescence detection (HPLC-FLD). Two-way analysis of variance was performed (GLM procedure of SAS) with fixed effects of smoking (S), muscle (M) and their interaction (SxM). Of the PAHs investigated, 14 compounds were detected. The results showed that TRAD hams had higher levels of anthracene (Ant), chrysene (Chr), benzo[b]fluoranthene (BbFA), benzo[a]pyrene (BaP), and the sum of benz[a]anthracene (BaA), Chr, BbFA and BaP (PAH 4) than hams from both A and B IND groups. TRAD hams had also higher content of acenaphthene (Acp), phenanthrene (Phen), pyrene (Py), BaA, and total PAHs than IND B hams. Compared to BF, SM muscle had higher content of several PAHs i.e. naphthalene (Nap), fluorine (Flu), Acp, Phen, Ant, fluoranthene (Flt), Py, BaA, benzo[k]fluoranthene (BkFA), benzo[ghi]perylene (BghiP), and also higher total PAH content. However, a significant SxM interaction was observed for Phen and Ant content which were higher only in SM muscle of TRAD hams. In conclusion, this study shows a marked influence of smoking method and anatomical site on the PAHs content in Turopolje hams, mainly in the form of lower BaP and the sum of PAH4 content in all chamber smoked hams compared to traditionally smoked hams and higher levels of light PAHs, some heavy PAHs and total PAH content in the more exposed SM compared to the inner BF muscle. Reduced smoking in IND hams did not affect BaP and the sum of PAH4 content, but reduced the content of some individual and total PAHs content. All IND hams and TRAD hams were below the maximum permitted level for BaP. However, two out of five hams from the TRAD group exceeded the limit for the sum of PAH4 (30 μg/kg) set by EU legislation for traditionally smoked meat products, indicating the need for stricter control of the traditional smoking process.

Physicochemistry and comparative metagenomics of a tropical estuary persistently inundated with anthropogenic pollutants.

The physicochemistry, metabolic properties, and microbial community structure of a tropical estuary persistently inundated with anthropogenic pollutants were elucidated using diverse analytical tools and a shotgun metagenomics approach. The physicochemistry of the Awoye estuary surface water (AEW) and sediment (AES) revealed higher values in the sediment for most of the parameters analyzed, while aside from copper and zinc, the concentrations of the detected heavy metals (Cd, Cr, Pb, Fe, As, Ni, Hg, Mn, Se) in the water and sediment were higher than the acceptable thresholds. Hydrocarbon content analysis revealed increasingly high concentrations of high molecular weight polycyclic aromatic hydrocarbons (HMW PAHs) in the sediment. Structurally, the predominant taxa in the AEW metagenome are Proteobacteria (50.35%), Alphaproteobacteria (43.31%), Brevundimonas (49.96%), and Leptolyngbya boryana (14.93%), while in the sediment (AES) metagenome, Proteobacteria (53.03%), Gammaproteobacteria (28.66%), Azospirillum (6.51%), and Acidihalobacter prosperus (7.56%) were preponderant. Statistical analysis of the two microbiomes (AEW, AES) revealed significant statistical differences (P < 0.05) at all the hierarchical levels. Functional characterization of the two metagenomes revealed extensive adaptations of the sediment microbiome to various environmental stressors as evident in the high numbers of putative genes involved in the degradation of diverse classes of aromatic hydrocarbons, efflux, detoxification, and transport of heavy metals, and metabolism of organic/inorganic nutrients. Findings from this study revealed that the estuary sediment is the sink for most of the anthropogenic pollutants and harbors the more adapted microbiome that could serve as a potential bioresource for the bioremediation of the perturbed estuary.

Impact of Thermal Process on Polycyclic Aromatic Hydrocarbons in Rabbit Meat

Abstract Rabbit meat represents food with a chemical composition beneficial to the human body. Due to its protein content and low fat levels, it is widely used in the diet of people with various health problems. Through preparation and heat treatments, some components lose their value, and these treatments can also increase the content of compounds that can be toxic to the human body. The sensory characteristics obtained after frying and smoking are appreciated by most consumers. The highest average values are for phenanthrene, both in smoked and fried meats and in raw rabbit meat. Among the hydrocarbons analyzed, benzo(a)anthracene is in the lowest quantity, This study shows the influence of some cooking, frying and smoking processes on the content of polycyclic aromatic hydrocarbons in rabbit meat.

Performance and mechanism of bio-oil "chain-pyrolytic" crumb rubber and SBS composite modified asphalt

To enhance the high-temperature performance of bio-oil degraded crumb rubber (CR) modified asphalt, a "chain-pyrolysis" treatment of CR was conducted using waste frying oil. This involved adding the CR in batches to the high-temperature waste oil to increase the CR-to-oil ratio, and control the degree of CR degradation. The effects of pyrolysis batch on the physicochemical properties of CR were evaluated through solubility, particle size analysis, thermal analysis, and scanning electron microscope. The performance and mechanism of "chain-pyrolytic" crumb rubber/Styrene-Butadiene-Styrene composite modified asphalt (PCR/SBSCMA) were investigated using conventional performance tests, rheological tests, Fourier transform infrared spectroscopy, fluorescence microscopy, and atomic force microscope. Results show that during the "chain-pyrolysis" process of CR, the sol content decreases, reaching a plateau after 3 batches and decreasing after 7 batches, indicating a decline in degradation degree. The particle size increases, whereas the rubber hydrocarbon content marginally rises, and the surface texture complexity diminishes with each batch. With an escalation in pyrolysis batch of CR, the penetration of the PCR/SBSCMA hits a minimum, the ductility gradually diminishes and the softening point slowly increases after 3 batches. The phase angle and non-recoverable creep compliance decrease, while the complex shear modulus and recovery rate enhance, significantly boosting the elasticity of the modified asphalt. The preparation of PCR and modification of PCR/SBSCMA contain the cleavage of sulfur bonds, the formation of oxygen functional groups, and the CR swelling. The uniform dispersion of polymer phases, presence of fine carbon black, and establishment of a stable colloidal system contribute the high-temperature mechanical properties and stability of the PCR/SBSCMA. The reduction of light components in the PCR/SBSCMA caused by swollen CR results in diminished surface roughness, disappeared "bee-like" structure, and improved homogeneity, which is conducive to low-temperature ductility. Overall, the PCR/SBS composite modification method promotes the high-quality and sustainable development of the utilization of waste tires and biomass in asphalt pavement.

Enhancing bioremediation of diesel/biodiesel blend (B20) impacted sites using in situ bioreactors: A nature-based solution for sustainable groundwater management

The rise of biodiesel content in diesel/biodiesel blends as a viable alternative to traditional diesel fuel presents several advantages, particularly in terms of reduced emissions of pollutants like carbon monoxide (CO), hydrocarbons (HC), and smoke. However, the increased production and utilization of biodiesel raise concerns about potential environmental impacts, such as groundwater pollution. This has led to a growing need for sustainable and effective bioremediation techniques to address these issues and ensure the safe closure of contaminated sites in accordance with environmental regulatory criteria. Two experimental areas contaminated with B20 (80% diesel and 20% biodiesel v/v) to evaluate ammonium acetate biostimulation (B20_BAA) and natural source zone depletion (B20_NSZD) as remediation strategies were monitored for 10 and 12 years, respectively. Although the benzene half-life was 1.49 and 4.08 years, respectively, hydrocarbon concentrations remained above the maximum contaminant level (MCL) allowed in Brazil for groundwater, requiring additional technologies for site cleanup. Then, two pilot-scale airlift bioreactors were employed as nature-based solutions (NbS) to reduce the concentration of persistent contaminants for site closure. Indeed, concentrations of benzene and 2-methylnaphthalene decreased significantly after the bioreactors began operation, reaching values below their respective MCL. 16S rRNA gene sequencing showed a beneficial response of microbial communities composed of Massilia, Burkholderia-Caballeronia-Paraburkholderia, Mycobacterium and Bacillus genus involved in hydrocarbons aerobic biodegradation. Moreover, predicted functional genes analysis demonstrated that the relative abundances of key aerobic degradation pathways for benzene and 2-methylnaphthalene increased, supporting the hypothesis that the NbS stimulated the hydrocarbons biodegradation. These findings demonstrated that combining different nature-based solutions (NbS) can effectively remediate petroleum hydrocarbons in contaminated groundwater through geochemical characteristics and exploration of indigenous microorganisms. To the best of the authors’ knowledge, this is the first study to employ bioreactors to treat B20-contaminated groundwater at a field scale.

Assessing data variability in groundwater quality monitoring of contaminated sites through factor analysis and multiple linear regression models

Monitoring of long-term contaminant concentrations trends is essential to verify that attenuation processes are effectively occurring at a site. However, monitoring data are often affected by extreme variability which prevents the identification of clear concentration trends. The variability is higher in long-screened monitoring wells, which are currently used at many contaminated sites, although it has been known since the 1980s that monitoring data from long-screened wells can be biased. Understanding the factors that may influence the variability of monitoring data is pivotal. To this end, following hydrochemical conceptual modelling using a multi-method approach, the variability of hydrocarbon concentrations from fully screened monitoring wells was assessed over eleven years at a former oil refinery located in Northern Italy. The proposed methodology combined factor analysis with multiple linear regression models.Results pointed out a higher variability in hydrocarbon concentrations at the plume fringe and a lower variability at the plume source and core. 44–46 % of the total variability in measured hydrocarbon concentrations is due to “intrinsic plume heterogeneity”, related to the three-dimensional structure of a contaminant plume, which becomes thinner at the edge, creating a vertical heterogeneity of redox conditions at the plume fringe. This variability, expressed as increasing concentrations of sulfate and decreasing concentrations of methane, represents a background variability that cannot be reduced by improving sampling procedures. The remaining 56–54 % of the total variability may be due to the non-standardization of some purging and sampling operations, such as pump intake position, purging and sampling time/flow rates and variations in the analytical methods. This finding suggests that monitoring improvements in fully screened wells by standardizing all purging/sampling operations or using sampling techniques that can reduce the actual screen length (e.g., packers or separation/dual pumping techniques) would reduce data variability by more than half.

Neural network potential-based molecular investigation of thermal decomposition mechanisms of ethylene and ammonia

This study developed neural network potentials (NNPs) specifically tailored for pure ethylene and ethylene-ammonia blended systems for the first time. The NNPs were trained on a dataset generated from density functional theory (DFT) calculations, combining the computational accuracy of DFT with a calculation speed comparable to reactive force field methods. The NNPs are employed in reactive molecular dynamics simulations to explore the thermal decomposition reaction mechanisms of ethylene and ammonia. The simulation results revealed that adding ammonia reduces the activation energy for ethylene decomposition, thereby accelerating ethylene consumption. Furthermore, the addition of ammonia uncovers a new reaction pathway for hydrogen radical consumption, which reduces the occurrence of H-abstraction reactions from ethylene by hydrogen radicals. The inhibition effect of ammonia addition on soot formation mainly acts in two aspects: on the one hand, ammonia decomposition products react with carbon-containing species, ultimately producing C1N products, thereby decreasing the carbon numbers involved in soot formation. This significantly reduces the concentrations of C5C9 molecules and key polycyclic aromatic hydrocarbons (PAHs) precursors like C2H2 and C3H3. On the other hand, ammonia promotes the ring-opening reactions of six-membered carbon rings at high-temperature conditions, thereby reducing the formation of PAHs precursors. The results show that with the addition of ammonia, six-membered carbon rings tend to convert into seven-membered carbon rings at lower temperatures, while at higher temperatures, they are more likely to transform into three- and five-membered carbon rings. These variations in the transformation of six-membered carbon rings may also affect soot formation. The insights gained from understanding these fundamental chemical reaction mechanisms can guide the development of ethylene-ammonia co-firing systems.

The Bioaccumulation and Risk Assessment of Total Petroleum Hydrocarbons in Aquatic Resources from K- Dere Shoreline, Rivers State, Nigeria

This research was designed to study the levels of Total Petroleum Hydrocarbon (TPH) in aquatic resources (Crab (Goniopsis cruentata), surface water and sediment) from K-Dere shoreline. Samples of sediment were collected intertidally. All samples were collected from six sampling stations, bi-monthly for a period of one year. Collected samples were transported to the laboratory for chemical analysis. Gas Chromatography was used to analyse total petroleum hydrocarbon concentration in samples and data obtained were statistically analysed at p&gt;0.05 using SPSS version 23. The mean concentration results obtained in surface water, sediment and biota across the stations were as follows; (590.75, 623.50, 451.17, 544.42, 674.67, 536.50mg/l) (8152.17, 6146.92, 44200.00, 4860.33, 2069.67and 5089.25mg/kg) and (131.5, 80.17,144.08, 109.08, 82.50, respectively. The mean concentration of TPH in sediment at station 1, 2 and 5 were above the intervention and permissible limit by the former DPR (2022). The ecological risk assessment was expressed in terms Bio-sediment Accumulation Factor (BSAF) and Pollution Index (PI) was calculated for the aquatic resources. PI showed that most chemical compounds of TPH were higher than 1, indicating high pollution from anthropogenic sources. The health risk assessment was expressed in terms of Estimated Daily Intake (EDI) and Health Risk Index (HRI) indicating significant health risk, posing threat to human health of the locals. Further and histopathological studies should be carried out to determine the impact of TPH on biota. Shoreline Clean up should be implemented with post clean-up assessment.

Network-based investigation of petroleum hydrocarbons-induced ecotoxicological effects and their risk assessment

Petroleum hydrocarbons (PHs) are compounds composed mostly of carbon and hydrogen, originating from crude oil and its derivatives. PHs are primarily released into the environment through the diffusion of oils, resulting from anthropogenic activities like transportation and offshore drilling, and accidental incidents such as oil spills. Once released, these PHs can persist in different ecosystems and cause long-term detrimental ecological impacts. While the hazards associated with such PH contaminations are often assessed by the concentrations of total petroleum hydrocarbons in the environment, studies focusing on the risks associated with individual PHs are limited. In this study, different network-based frameworks were utilized to explore and understand the adverse ecological effects associated with PH exposure. First, a list of 320 PHs was systematically curated from published reports. Next, biological endpoint data from toxicological databases was systematically integrated, and a stressor-centric adverse outcome pathway (AOP) network, linking 75 PHs with 177 ecotoxicologically-relevant high confidence AOPs within AOP-Wiki, was constructed. Further, stressor-species networks, based on reported toxicity concentrations and bioconcentration factors data within ECOTOX, were constructed for 80 PHs and 28 PHs, respectively. It was found that crustaceans are documented to be affected by many of these PHs. Finally, the aquatic toxicity data within ECOTOX was used to construct species sensitivity distributions for PHs, and their corresponding hazard concentrations (HC05), that are harmful to 5% of species in the aquatic ecosystem, were derived. Further, the predicted no-effect concentrations (PNECs) and risk quotients for the US EPA priority polycyclic aromatic hydrocarbons (PAHs) were computed by using their environmental concentration data for Indian coastal and river waters. Overall, this study highlights the importance of using network-based approaches and risk assessment methods to understand the PH-induced toxicities effectively.

Catalyst screening for conversion of Chlorella sp. to aromatic fuel additives: A sustainable strategy for CO2 capture

Developing biofuels with characteristics similar to current fossil fuels and compatibility with existing petroleum infrastructure (drop-in biofuels) is gaining prominence, aligning with global efforts towards carbon-neutral economies and decarbonization of the transportation sector. The originality of the current study involves two directions: first, the use of Chlorella sp. microalgae, cultivated under simulated post-combustion gas, as a raw material for producing drop-in biofuel precursors; and second, an investigation of the catalytic activity of hierarchical zeolites in the deoxygenation and denitrogenation of volatile pyrolysis products, enhancing hydrocarbon content. To accomplish this, a micro-furnace-type temperature-programmable pyrolyzer coupled with chromatographic separation and mass spectrometry detection (Py-GC/MS) was utilized to assess the upgrading effectiveness of distinct zeolites (faujasite-type, MFI-type, and mordenite-type) on volatile pyrolysis products. All tested zeolites effectively reduced oxygenated and nitrogenated compounds in the volatile pyrolysis products, enhancing their suitability for producing renewable fuel. This supports sustainable development goals by promoting affordable, clean energy and climate action. HMor yielded the highest hydrocarbon content (98.5 %), followed by HZSM-5 (97.6 %) and HY (85.5 %). Catalytic upgrading significantly increased the concentration of aromatic hydrocarbons (at least 66.3 %), with MFI-type zeolites showing the highest selectivity for valuable BETX compounds (benzene, ethylbenzene, toluene, xylene). Hydrocarbons in the gasoline range, with up to 91.7 %, predominantly align with the needs of the transportation fuel market. The principal component analysis illustrates that using MFI-type zeolites promoted the lowest selectivity for PAHs, constituting precursors for coke formation, which is advantageous for ensuring a longer catalyst lifespan. Our results are promising and encourage the conversion of microalgal biomass into renewable fuel additives for formulating drop-in biofuels, as hydrocarbon-rich volatile pyrolysis products could be directly integrated into existing biorefineries. Thus, microalgal biomass cultivated using flue gas as the carbon source can be viewed as a versatile and promising resource for producing renewable fuel additives, contributing to developing a sustainable, low-carbon future.

Characterization of Indoor Air Quality in a University Library: Implications Associated with Pollutant Emissions from New and Old Books and Chemicals

During a 1-year study, organic aerosol indoor air samples were collected from sites in a library in Rio de Janeiro, Brazil. Indoor air is a cause for public concern in Brazil. This study presents an indoor air survey wherein the concentrations of aliphatic hydrocarbons, phthalates, phenyl phosphates, aldehydes, limonene, organic acids, and particulate matter were determined. Acids were estimated to be ranging between 0.01 and 30.26 ng m−3, whereas furfural ranged between 0.5 and 3.6 g m−3. Compounds such as furfural, hexanal, benzaldehyde, and vanillin were only detected indoors. Results showed that total suspended particle concentrations were higher outdoors than indoors. Interestingly, 1, 1, 1-trichloro-2, 2-bischlorophenylethane (DDT), and its derivatives were also present. Pesticides are used in libraries to control paper-degrading pests. Therefore, DDT and other chemicals remain nondegraded and pollute the library rooms. This study demonstrates the relevance of monitoring indoor air quality in libraries and the pollutants that can affect the well-being of occupants. Moreover, indoor air quality monitoring can provide early warning to library managers about the effects of indoor air characteristics on unprotected and/or preserved items.

Combustion Temperature and Soil Organic Horizons Composition Influence on the PAHs Content (Laboratory Experiment Results)

Fire induced changes in the content and composition of polycyclic aromatic hydrocarbons (PAHs) in organic horizons of the boreal zone soils are considered. Experiment of combustion under oxygen deficient conditions were conducted. The organic horizons of soils as peat (sphagnum oligotrophic) and two types of forests (lichen pine and green-moss spruce) were selected. The PAHs content was determined by high-performance liquid chromatography. It was found that combustion conditions, composition of organic horizons and combustibility significantly affect the content and composition of PAHs. The formation of PAHs occurs to a greater extent at 300°C. Compared with the original samples, the content increases from 2.7 to 9.7 times. Compared with the peak PAHs content (in 300°C) samples, a decrease from 5.8 to 33.0 times is found at 500°C. It is likely that the significant decrease in the content of polycyclic aromatic hydrocarbons is due to the decomposition of substances to simpler ones. The ratio of low molecular to high molecular weight PAHs is indicated. The obtained ratio greater than 1.0 can serve as an indicator of pyrogenic origin of polyarenes.

Production of aromatic hydrocarbons from catalytic fast pyrolysis of microalgae over Fe-modified HZSM-5 catalysts.

In this study, catalytic fast pyrolysis of the microalga C. pyrenoidosa over Fe-modified HZSM-5 catalysts was performed to produce aromatic hydrocarbons using analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Fe-modified HZSM-5 catalysts were prepared using wet impregnation and characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), N2 adsorption-desorption and temperature-programmed desorption of ammonia (NH3-TPD) analysis. The effect of Fe loading (3, 5, 8, and 12 wt%) and pyrolysis temperature (450, 500, 550, 600 °C) on the content of pyrolysis products and the content and selectivity of aromatics was examined. Results showed that the parent HZSM-5 catalyst structure remained intact upon increasing Fe loading, although its specific surface area, micropore volume and average pore diameter decreased. In addition, its external specific surface area and total pore volume increased. The modification of Fe metal increased the total acid amount, especially strong acid sites, which were highest when Fe loading was 8 wt%. The prepared Fe-modified HZSM-5 catalysts exhibited pronounced deoxygenation and denitrogenation effects, which significantly decreased the acid, aldehyde, ketone, furan and nitrogenous compounds, thus improving the production of monocyclic aromatic hydrocarbons (MAHs) while effectively suppressing the formation of polycyclic aromatic hydrocarbons (PAHs). The highest content of aromatic hydrocarbons was obtained with an Fe loading of 8 wt% and pyrolysis temperature of 500 °C, which was 42.5%. As Fe loading increased, benzene selectivity decreased, while the selectivity of toluene and xylene first increased and then decreased. With an increase in pyrolysis temperature, benzene selectivity increased, whereas toluene and xylene selectivity increased at first and then decreased. Reaction mechanisms for the formation of aromatic hydrocarbons during the catalytic pyrolysis of microalgae are put forward. This research revealed that catalytic fast pyrolysis of microalgae over Fe-modified HZSM-5 catalysts is an effective method to produce MAHs.

Hygienic aspects of ensuring chemical safety of using new health-saving technologies for the utilization of biogas at solid municipal waste landfills

Introduction. Environmental health issues are currently among the most important for the population of large administrative and industrial centers. Improving the quality of the environment and creating comfortable living conditions for humans using environmentally friendly methods is one of the current topical areas in environmental hygiene. Materials and methods. The assessment of the effectiveness and chemical safety of the application of a new technology for the collection, purification, neutralization, and disposal of landfill gas for the content of a wide range of organic compounds C5–C20 at a municipal solid waste landfill was carried out using a chromato-mass spectrometric method that allows identifying and quantifying with sensitivity at and below hygienic standards a wide range of organic compounds C5–C20 in air with an unknown composition of pollutants. Results. As a result of the operation of the new landfill gas purification system at the solid waste landfill, the total concentration of pollutants, including marginal and aromatic hydrocarbons, oxygen-containing compounds (alcohols, carboxylic acids), organic sulfur-containing compounds, and sulfur dioxide decreased. As a result of the operation of the new landfill gas purification technology, 100% purification from odourous dialkyl sulfides and nitrogen-containing compounds has been achieved. However, at the outlet of the system, compounds not detected at the inlet were identified, which can be considered as products of combustion and transformation of hydrocarbons that are part of landfill gas, the presence of which indicates to the use of an oxidative process in the process of its disposal. Limitations. The study is limited to the application of the method of investigation of organic compounds with the molecular formula C5–C20. Conclusion. For an adequate assessment of the quality and chemical safety to human health of health-saving technologies, an important condition is the use of physical-chemical studies that identify and quantify dozens of pollutants simultaneously, which makes it possible to take into account the multiple componentness of the chemical composition and the possibility of adverse side effects in the form of toxic transformation of products affecting humans in real environmental pollution conditions.

A comprehensive evaluation of bioremediation effects of oil-contaminated soils using various dosages of exogenous nitrogen supplementation: TPH removal, ecological toxicity, and microecological response

Biostimulation with exogenous nitrogen addition is a common strategy for remediation of petroleum-contaminated soils. However, the comprehensive effects of various dosages of exogenous nitrogen application on hydrocarbon removal, soil ecotoxicity, and microecological response are not clear. In this study, a petroleum-contaminated soil with total petroleum hydrocarbon (TPH) content of 8553 mg/kg was remediated by adding NH4Cl to adjust C/N ratio of 100/1(N1), 100/2(N2), 100/5(N3), and 100/10(N4), respectively. After 210 days of remediation, the TPH removal efficiency was the highest in the N2(32.55 %) when compared with that in the N1(28.43 %), N3(27.87 %) and N4 (22.60 %) treatments. PICRUSt2 analysis revealed that the abundances of oorA and oorB genes encoding EC 1.2.7.11 were significantly enhanced in the N1 and N2 but decreased in the N3 and N4 treatments, indicating that conversion of pyruvate to acetyl-CoA for participation in TCA cycle was enhanced due to low dosage of NH4Cl addition. The gene abundances of NxrA and NxrB encoding nitrification, nirK and nirS encoding denitrification in the N1 and N2 treatments were lower than those in the N3 and N4 treatments, suggesting low dose of NH4Cl addition reduces soil nitrogen loss and stabilizes taxonomic diversities. Acute toxicity test found that the earthworm weight inhibition rates in the N1, N2, N3, and N4 treatments were −2.48 %, 9.57 %, and 5.83 % and 60.21 %, respectively. This result revealed that NH4Cl application with C/N ratio of 100/2 contribute to TPH degradation and stabilization of soil ecological function, which were facilitated to remediation of petroleum-contaminated soil.