Search Results (644)

Polycyclic aromatic compounds can often be made by a sequence featuring an initial Diels–Alder [4 + 2] cycloaddition reaction, followed by cheletropic extrusion of carbon monoxide. These reactions normally require heating the diene and dieneophile in petrochemical-derived aromatic hydrocarbon solvents, such as xylenes or diphenyl ether. This article summarizes the results of attempts to use renewable solvents in place of those currently in use to prepare pentaphenylbenzene and 1,2,4-triphenyltriphenylene. Dihydrolevoglucosenone, p-cymene, ethyl lactate, diethyl carbonate, and cyclopentyl methyl ether have all been successfully evaluated as renewable solvent alternatives in Diels–Alder/cheletropic reaction sequences. An analysis of the products from the reactions investigated did not show evidence of oxidative degradation of the diene reactants. Furthermore, norbornadien-7-one intermediates were not isolated from any of the reactions tested. Full article

Rapid industrialization and urbanization have progressed in Korea, yet public attention to hazardous pollutants emitted from industrial complexes remains limited. With the increasing coexistence of industrial and residential areas, there is a growing need for real-time monitoring and management plans that account for the rapid dispersion of hazardous air pollutants (HAPs). In this study, we conducted spatiotemporal data collection and analysis for the first time in Korea using real-time measurements obtained through mobile extractive differential optical absorption spectroscopy (Me-DOAS) mounted on a solar occultation flux (SOF) vehicle. The measurements were conducted in the Saha Sinpyeong–Janglim Industrial Complex in Busan, which comprises the Sasang Industrial Complex and the Sinpyeong–Janglim Industrial Complex. BTEX compounds were selected as target volatile organic compounds (VOCs), and real-time measurements of both BTEX and fine particulate matter (PM) were conducted simultaneously. Correlation analysis revealed a strong relationship between PM₁₀ and PM_2.5 (r = 0.848–0.894), indicating shared sources. In Sasang, BTEX levels were associated with traffic and localized facilities, while in Saha Sinpyeong–Janglim, the concentrations were more influenced by industrial zoning and wind patterns. Notably, inter-compound correlations such as benzene–m-xylene and p-xylene–toluene suggested possible co-emission sources. This study proposes a GIS-based, three-dimensional air quality management approach that integrates variables such as traffic volume, wind direction, and speed through real-time measurements. The findings are expected to inform effective pollution control strategies and future environmental management plans for industrial complexes. Full article

The recovery and abatement of volatile organic compounds (VOCs) have received increasing attention due to their significant environmental and health impacts. Supported sulfonic acid materials have shown great potential in converting aromatic VOCs into their non-volatile derivatives through reactive adsorption. However, the anchoring state of sulfonic acid groups, which is closely related to the properties of the support, greatly affects their performance. In this study, two supported sulfonic acid materials, SZO and SMO, were prepared by treating ZrO₂ and MgO with chlorosulfonic acid, respectively, to investigate the influence of the support properties on the anchoring state of sulfonic acid groups and their reactive adsorption performance for o-xylene. The supports, adsorbents, and adsorption products were extensively characterized, and the reactivity of SZO and SMO towards o-xylene was systematically compared. The results showed that sulfonic acid groups are anchored on the ZrO₂ surface through covalent bonding, forming positively charged sulfonic acid sites ([O_1.5Zr-O]^δ−-SO3H^δ+) with a loading of 3.6 mmol/g. As a result, SZO exhibited excellent removal efficiency (≥91.3%) and high breakthrough adsorption capacity (ranging from 38.59 to 82.07 mg/g) for o-xylene in the temperature range of 130 –150 °C. In contrast, sulfonic acid groups are anchored on the MgO surface via ion-paired bonding, leading to the formation of negatively charged sulfonic acid sites ([O_0.5Mg]⁺:OSO₃H⁻), which prevents their participation in the electrophilic sulfonation reaction with o-xylene molecules. This work provides new insights into tuning and enhancing the performance of supported sulfonic acid materials for the resource-oriented treatment of aromatic VOCs. Full article

This study provides an assessment of BTEX compounds—benzene, toluene, ethylbenzene, and xylene isomers—in urban precipitation collected in the city of Novi Sad, Republic of Serbia, during autumn and winter 2024, analyzed by gas chromatography-mass spectrometry (GC-MS). By combining chemical analysis with meteorological observations and HYSPLIT backward trajectory modeling, the study considers the mechanisms of BTEX removal from the atmosphere via wet scavenging and highlights the role of local weather conditions and long-range atmospheric transport in pollutant concentrations. During the early observation period (September to late November), average concentrations were 0.45 µg/L benzene, 3.45 µg/L ethylbenzene, 4.0 µg/L p-xylene, 2.31 µg/L o-xylene, and 1.32 µg/L toluene. These values sharply dropped to near-zero levels in December for benzene, ethylbenzene, and xylenes, while toluene persisted at 1.12 µg/L. A pronounced toluene spike exceeding 6 µg/L on 28 November was likely driven by transboundary air mass transport from Central Europe, as confirmed by trajectory modeling. The environmental risks posed by BTEX deposition, especially from toluene and xylenes, underline the need for regulatory frameworks to include precipitation as a pathway for pollutant deposition. It should be clarified that the identified risk primarily concerns aquatic organisms, due to the potential for BTEX infiltration into surface waters and subsequent ecotoxicological impacts. Incorporating such monitoring into EU policies can improve protection of air, water, and ecosystems. Full article

This study aimed to investigate the concentrations of BTEX (benzene, toluene, ethylbenzene, ortho-xylene (o-), and meta and para-xylene (m-,p-)) in Croatian households between December 2023 and January 2025. The results showed that BTEX concentrations were higher indoors than outdoors, suggesting a considerable contribution from indoor sources. Significant statistical differences were found between indoor and outdoor levels of ethylbenzene, m-,p-xylene, and o-xylene, especially during cold periods when indoor activities increase and ventilation decreases. Spearman’s correlation analysis showed weak correlations between benzene and other BTEX compounds, implying multiple distinct sources such as cooking, smoking, and outdoor air infiltration. Full article

The aim of this work was the preparation of ceramic monolithic catalysts for the catalytic oxidation of gaseous mixture of benzene, toluene, ethylbenzene and o-xylene BTEX. The possibility of using zirconium dioxide (ZrO₂) as a filament for the fabrication of 3D-printed ceramic monolithic carriers was investigated using fused filament fabrication. A mixed manganese and iron oxide, MnFeO_x, was used as the catalytically active layer, which was applied to the monolithic substrate by wet impregnation. The approximate geometric surface area of the obtained carrier was determined to be 53.4 cm², while the mass of the applied catalytically active layer was 50.3 mg. The activity of the prepared monolithic catalysts for the oxidation of BTEX was tested at different temperatures and space times. The results obtained were compared with those obtained with commercial monolithic catalysts made of ceramic cordierite with different channel dimensions, and with monolithic catalysts prepared by stereolithography. In the last part of the work, a kinetic analysis and the modeling of the monolithic reactor were carried out, comparing the experimental results with the theoretical results obtained with the 1D pseudo-homogeneous and 1D heterogeneous models. Although both models could describe the investigated experimental system very well, the 1D heterogeneous model is preferable, as it takes into account the heterogeneity of the reaction system and therefore provides a more realistic description. Full article

This study investigates the emission characteristics and environmental impacts of pollutants from bagasse-fired biomass boilers through the integrated field monitoring of two sugarcane processing plants in Guangxi, China. Comprehensive analyses of flue gas components, including PM_2.5, NOx, CO, heavy metals, VOCs, HCl, and HF, revealed distinct physicochemical and emission profiles. Bagasse exhibited lower C, H, and S content but higher moisture (47~53%) and O (24~30%) levels compared to coal, reducing the calorific values (8.93~11.89 MJ/kg). Particulate matter removal efficiency exceeded 98% (water film dust collector) and 95% (bag filter), while NOx removal varied (10~56%) due to water solubility differences. Heavy metals (Cu, Cr, Ni, Pb) in fuel migrated to fly ash and flue gas, with Hg and Mn showing notable volatility. VOC speciation identified oxygenated compounds (OVOCs, 87%) as dominant in small boilers, while aromatics (60%) and alkenes (34%) prevailed in larger systems. Ozone formation potential (OFP: 3.34~4.39 mg/m³) and secondary organic aerosol formation potential (SOAFP: 0.33~1.9 mg/m³) highlighted aromatic hydrocarbons (e.g., benzene, xylene) as critical contributors to secondary pollution. Despite compliance with current emission standards (e.g., PM < 20 mg/m³), elevated CO (>1000 mg/m³) in large boilers indicated incomplete combustion. This work underscores the necessity of tailored control strategies for OVOCs, aromatics, and heavy metals, advocating for stricter fuel quality and clear emission standards to align biomass energy utilization with environmental sustainability goals. Full article

Benzene, toluene, ethylbenzene, and xylene (BTEX) are widespread volatile organic compounds commonly present in fuels and various industrial materials. Their release into the atmosphere significantly contributes to air pollution, prompting strict regulatory concentration limits in ambient air. In this work, we introduce Multiphoton Electron Extraction Spectroscopy (MEES) as an innovative technique for the sensitive, selective, and online detection and quantitation of BTEX compounds under ambient conditions. MEES employs tunable UV laser pulses to induce the resonant ionization of target molecules under a high electrical field, with subsequent measurement of the generated photocurrent. We now demonstrate the method’s ability to detect BTEX in ambient air, at part-per-trillion (ppt) concentration range, providing distinct spectral signatures for each compound, including individual xylene isomers. The technique represents a significant advancement in BTEX monitoring, with potential applications in environmental sensing and industrial air quality control. Full article

The paper titled “Methods for a Non-Targeted Qualitative Analysis and Quantification of Benzene, Toluene, and Xylenes by Gas Chromatography-Mass Spectrometry of E-Liquids and Aerosols in Commercially Available Electronic Cigarettes in Mexico” was submitted in compliance with all the requirements of the editorial and journal in question, as evidenced by the dates and the respective backup documentation [...] Full article

The seasonal variations, spatial distribution, and health risk assessment of 13 volatile organic compounds (VOCs), particularly benzene, toluene, ethyl benzene, and xylene (BTEX), in the ambient air of Dilovası, a Turkish city with unplanned urbanization, are presented in this study. Using passive tube sampling, at 22 locations in Dilovası, air samples were collected separately for the summer and winter, and concentrations were measured using thermal desorption GC-MS. Pollution maps were created using the Golden Software Surfer program and QGIS Desktop 3.42.0 software program. A health risk evaluation was conducted using the US Environmental Protection Agency’s (USEPA) approach. The study’s findings demonstrated that the atmospheric VOC concentrations at the sampling locations varied significantly by season and location. According to a carcinogenic risk assessment, residents in this area may be more susceptible to cancer if they are exposed to benzene, ethylbenzene, and naphthalene over an extended period. A non-carcinogenic risk (HQ) evaluation determined that while there was no significant risk at 21 measurement points, there was a substantial risk for non-cancer health effects at 1 measurement point. The significance of regulatory policies and pollution control technologies has once again emerged in this context. Full article

This study investigates hazardous emissions from foundry binder systems, comparing organic resins (phenolic urethane, furan, and alkaline-phenolic) and clay-bonded green sand with inorganic alternatives (sodium silicate and geopolymer). The research was conducted at the Fundaciόn Azterlan pilot plant (Spain), involving controlled chamber tests for the production of 60 kg iron alloy castings in 110 kg sand molds. The molds were evaluated under two configurations: homogeneous systems, where both mold and cores were manufactured using the same binder (five trials), and heterogeneous systems, where different binders were used for mold and cores (four trials). Each mold was placed in a metallic box fitted with a lid and an integrated gas extraction duct. The lid remained open during pouring and was closed immediately afterward to enable efficient evacuation of casting gases through the extraction system. Although the box was not completely airtight, it was designed to direct most exhaust gases through the duct. Along the extraction system line, different sampling instruments were strategically located for the precise measurement of contaminants: volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), phenol, multiple forms of particulate matter (including crystalline silica content), and gases produced during pyrolysis. Across the nine trials, inorganic binders demonstrated significant reductions in gas emissions and priority pollutants, achieving decreases of over 90% in BTEX compounds (benzene, toluene, ethylbenzene, and xylene) and over 94% in PAHs compared to organic systems. Gas emissions were also substantially reduced, with CO emissions lowered by over 30%, NO_x by more than 98%, and SO₂ by over 75%. Conducted under the Greencasting LIFE project (LIFE 21 ENV/FI/101074439), this work provides empirical evidence supporting sodium silicate and geopolymer binders as viable, sustainable solutions for minimizing occupational and ecological risks in metal casting processes. Full article

Most studies have focused on the levels of pollutants in drinking water and the health risks they pose. However, no studies have reported the effects of drinking water intake on pollutant levels in the human body. Therefore, this study collected data from National Health and Nutrition Examination Survey database to provide statistical evidence for the relationship between water intake and human pollutant levels. We analyzed 95 pollutants in human urine, blood, and serum. The study found that 82% (65/79) of urine pollutants unadjusted for creatinine showed a stable negative correlation with water intake, primarily due to the urine dilution effect caused by increased water consumption. Water intake was negatively correlated with cadmium, m-/p-xylene, and toluene in blood, but positively correlated with blood total mercury and methyl mercury. In summary, the habit of drinking more water may be beneficial to reduce levels of most pollutants in human urine (unadjusted for creatinine) and a small part in blood. Only a few pollutants, including total mercury and methyl mercury in blood, as well as benzophenone-3 in urine (both creatinine-adjusted and unadjusted), are positively related to water intake. The underlying mechanisms by which water intake influences pollutant levels in the human body require further investigation. Full article

Spodoptera frugiperda, a major global agricultural pest, poses significant challenges to chemical control methods due to pesticide resistance and environmental concerns, underscoring the need for sustainable management strategies. Attractants based on host plant volatiles offer a promising eco-friendly approach, but their development for S. frugiperda is hindered by limited research on host recognition mechanisms. This study reveals that female S. frugiperda preferentially oviposit on maize at the seedling stage. Using electrophysiological techniques, we identified p-xylene and (+)-camphor from seedling-stage maize volatiles as key compounds eliciting strong responses in female S. frugiperda. Behavioral assays confirmed that these compounds (p-xylene at the concentration of 5%, 10%, and 20% and (+)-camphor at 1%, 5%, and 10%) significantly attract females, establishing them as the key odor cues for host selection. Moreover, these volatiles are more abundant in seedling-stage maize, suggesting that S. frugiperda assesses maize growth stages based on their concentrations. Importantly, larvae reared on seedling-stage maize exhibited higher survival rates than those on later-stage maize, indicating that oviposition site selection directly affects offspring fitness. These findings demonstrate that S. frugiperda uses p-xylene and (+)-camphor to evaluate maize development and select suitable oviposition sites, thereby enhancing larval survival. This study provides a foundation for developing targeted attractants for S. frugiperda and highlights the seedling stage as a critical period for implementing pest control measures, particularly in autumn maize production, given the higher pest population density during this phase. Full article

Despite significant advancements in designing tandem catalysts for CO₂ hydrogenation to aromatics, the role of zeolite acid property in regulating the selectivity of light aromatics (benzene, toluene, and xylene, abbreviated as BTX) remains unclear. Herein, we report H-ZSM-5 zeolite (denoted as HZ-X, where X represents the Si/Al ratio) integrated with a Na-promoted FeCo-based catalyst (NaFeCo) for CO₂ hydrogenation into aromatics via a modified Fischer–Tropsch synthesis pathway. This study systematically modulates the Si/Al ratio of acidic zeolite and examines its critical role in influencing the light aromatics selectivity. The optimized NaFeCo/HZ-50 catalyst achieves a CO₂ conversion of 43% with an aromatics selectivity of 41%, including a BTX fraction of 57% in total aromatics. Multiple characterization techniques (NH₃-TPD, Py/DTBPy-IR, ²⁷Al NMR, etc.) clarify that acidic zeolite HZ-50 exhibits appropriate acid density and lower external surface acid sites, which synergistically boost the efficient aromatics and BTX synthesis while suppressing the undesirable alkylation and isomerization reactions on the external acid sites. This work develops a highly efficient multifunctional catalyst for CO₂ hydrogenation to light aromatics, especially offering guidance for the rational design of acidic zeolite with unique shape-selective functions. Full article