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Long-term exposure to Volatile Organic Compounds (VOCs) is a health risk for citizens. In this study, the cumulative health risk of exposure to VOCs in Tehran was assessed by investigating the concentration of these pollutants in ambient air in a five-year period. Health risk assessment was calculated by the quantitative method and the carcinogenic risk level was determined using the lifetime carcinogenic risk (LCR) method. The average concentration of benzene, toluene, ortho-xylene, and ethylbenzene was 1.4–1.8, 4.8–5.4, 5–6.5, and 3.6–4 ppb, respectively. Although HQ was not greater than 1, but it was very close in the case of benzene, ortho-xylene, meta-xylene, and para-xylene. Benzene and ethylbenzene had the largest effect in the assessed health risk. So the long-term exposure of Tehran citizens to VOCs has serious health consequences for them, which could be different according to the exposure time and spatial variations. [ABSTRACT FROM AUTHOR]

A computational mechanistic study was performed to investigate the transfer hydrogenation of styrene catalysed by a potassium tris‐hexamethyldisilazide magnesiate in the presence of 1,4‐cyclohexadiene. Exploiting cooperative effects between Mg and K centres present in this tris(amide) complex results in the selective formation of the desired product ethylbenzene. The calculations demonstrate the synergy of the metal centres within the bimetallic complex, since neither the monometallic potassium amide K(HMDS) nor the magnesium amide Mg(HMDS)2 on their own can efficiently execute this transformation under the experimental conditions. Several distinct mechanistic pathways have been explored, leading to the identification of the most plausible sequence in which both metal centres act in a synchronised manner. [ABSTRACT FROM AUTHOR]

Recently, volatile organic compound (VOC) determination in exhaled breath has seen growing interest due to its promising potential in early diagnosis of several pathological conditions, including chronic kidney disease (CKD). Therefore, this study aimed to identify the breath VOC pattern providing an accurate, reproducible and fast CKD diagnosis at early stages of disease. A cross-sectional observational study was carried out, enrolling a total of 30 subjects matched for age and gender. More specifically, the breath samples were collected from (a) 10 patients with end-stage kidney disease (ESKD) before undergoing hemodialysis treatment (DIAL); (b) 10 patients with mild-moderate CKD (G) including 3 patients in stage G2 with mild albuminuria, and 7 patients in stage G3 and (c) 10 healthy controls (CTRL). For each volunteer, an end-tidal exhaled breath sample and an ambient air sample (AA) were collected at the same time on two sorbent tubes by an automated sampling system and analyzed by Thermal Desorption–Gas Chromatography–Mass Spectrometry. A total of 110 VOCs were detected in breath samples but only 42 showed significatively different levels with respect to AA. Nonparametric tests, such as Wilcoxon/Kruskal–Wallis tests, allowed us to identify the most weighting variables able to discriminate between AA, DIAL, G and CTRL breath samples. A promising multivariate data mining approach incorporating only selected variables (showing p-values lower than 0.05), such as nonanal, pentane, acetophenone, pentanone, undecane, butanedione, ethyl hexanol and benzene, was developed and cross-validated, providing a prediction accuracy equal to 87% and 100% in identifying patients with both mild–moderate CKD (G) and ESKD (DIAL), respectively. [ABSTRACT FROM AUTHOR]

A comprehensive DFT investigation has been presented to predict how a carboxylate-rich macrocycle would affect the reactivity of a non-heme Fe(IV)O complex towards C–H activation. The popular non-heme iron oxo complex [FeIV(O)(N4Py)]2+, (N4Py = N,N-(bis(2-pyridyl)methyl)N-bis(2-pyridylmethyl)amine) (1), has been selected here as the primary compound. It is transformed to the compound [FeIV(O)(nBu-P2DA)], where nBu-P2DA = N-(1′,1′-bis(2-pyridyl)pentyl)iminodiacetate (2) after the replacement of two pyridine donors of N4Py with carboxylate groups. Two other complexes, namely 3 and 4, have been predicted sequentially substituting nitrogen with the carboxylate groups. Ethylbenzene and dihydrotoluene were chosen as substrates. In terms of C–H activation reactivity, an interesting pattern emerges: as the carboxylate group becomes more equatorially enriched, the reactivity increases, following the trend 1 < 2 < 3 < 4. This also aligns with available experimental reports related to complexes 1 and 2. Fe(IV)O complexes exhibit two-state reactivity (triplet and quintet), whereas the quintet state is more favourable due to the stabilization of the transition states through exchange interactions involving a greater number of unpaired electrons. A detailed analysis of the factors influencing reactivity has been performed, including distortion energy (which decreases for the transition state with the addition of carboxylate groups), the triplet–quintet oxidant energy gap (which consistently decreases as carboxylate group enrichment increases), steric factors, and quantum mechanical tunneling. This investigation provides a detailed explanation of the observed outcomes and predicts the higher reactivity of carboxylate-enriched Fe(IV)O complexes. After potential experimental verification, this could lead to the development of new, optimal catalysts for C–H activation. [ABSTRACT FROM AUTHOR]

Unspecific Peroxygenases (UPOs) have emerged as robust biocatalysts for selective oxygenation reactions, as they are easily produced at scale and require only hydrogen peroxide as the external oxidant. UPOs can catalyze the oxygenation of the primary benzylic carbons of toluenes to give alcohol, aldehyde and carboxylic acid products. They can also catalyze hydroxylation at the benzylic position of ethylbenzenes, and the subsequent oxidation of the secondary alcohols to ketones. In this study, we have investigated factors that affect the balance of products in UPO‐catalyzed benzylic oxygenations using a range of functionalised toluenes and ethyl benzenes, and a UPO from Agrocybe aegerita (rAaeUPO‐PaDa‐I‐H variant). The product distribution is dependent upon a mixture of steric and electronic effects and, in selected cases, controlling the reaction conditions permits products from each product series to be generated chemoselectively. In this way, electron poor toluenes were converted directly into carboxylic acids in isolated yields of 36–99 % on preparative scale. [ABSTRACT FROM AUTHOR]

The removal of benzene, toluene, ethylbenzene, and xylene (BTEX) from air was investigated in two similar biotrickling filters (BTFs) packed with polyurethane (PU) foam, differing in terms of inoculation procedure (BTF A was packed with pre-incubated PU discs, and BTF B was inoculated via the continuous recirculation of a liquid inoculum). The effects of white rot fungi enzyme extract addition and system responses to variable VOC loading, liquid trickling patterns, and pH were studied. Positive effects of both packing incubation and enzyme addition on biotrickling filtration performance were identified. BFF A exhibited a shorter start-up period (approximately 20 days) and lower pressure drop (75 ± 6 mm H2O) than BTF B (30 days; 86 ± 5 mm H2O), indicating the superior effects of packing incubation over inoculum circulation during the biotrickling filter start-up. The novel approach of using white rot fungi extracts resulted in fast system recovery and enhanced process performance after the BTF acidification episode. Average BTEX elimination capacities of 28.8 ± 0.4 g/(m3 h) and 23.1 ± 0.4 g/(m3 h) were reached for BTF A and BTF B, respectively. This study presents new strategies for controlling and improving the abatement of BTEX in biotrickling filters. [ABSTRACT FROM AUTHOR]

Copyright of Petroleum Refinery Engineering is the property of Petroleum Refinery Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Changes caused by air-cleaning devices in the amounts of volatile organic compounds in an intensive care unit were monitored in the study. The cancer risk and hazard index were calculated. The measurements were made for one month at isolated room and two different points and times in the intensive care unit. According to the sampling program, the air-cleaning devices were turned off in weeks 1 and 4 and turned on in weeks 2 and 3. Volatile organic compounds were collected by active sampling. Samples were analyzed by a thermal desorber coupled to a gas chromatography-mass spectrometry instrument with selective ion monitoring. The results showed that the concentrations of benzene, toluene, and o-xylene decreased by about 70% after the air-cleaning devices were installed. The cancer risk assessment for naphthalene was recorded at the highest level of cancer risk (Class A). The hazard index value of naphthalene was recorded at the harmful level when air-cleaning devices were not installed. The concentrations of benzene (p = 0.01), toluene (p = 0.02), ethylbenzene (p = 0.02), styrene (p = 0.01), and m, p-xylene (p = 0.04) before the air-cleaning devices were installed were significantly different from those recorded when the air-cleaning devices were turned on. [ABSTRACT FROM AUTHOR]

Aim: Volatile organic compounds (VOCs) are often human-made contaminants used and generated in the manufacturing of numerous products, presenting notable environmental and health hazards. Therefore, the development of sensitive and reliable analytical methods is crucial for their detection with accuracy, timeliness, and automation capabilities. The objective of this study is to demonstrate the suitability of the in-tube extraction dynamic headspace (ITEX-DHS) sampling method for the gas chromatographic/mass spectrometric (GC/MS) analysis of BTEX (benzene, toluene, ethylbenzene, and xylenes) compounds in aqueous matrices. It emphasizes the method’s metrological reliability and innovative approach to precisely determining VOCs in aqueous environments providing a tool to prevent contamination of the agrifood sector. Methods: Following the optimization of various experimental parameters, including salt incorporation and adjustments of both dry purging and desorption conditions. The method’s performance was evaluated for repeatability, reproducibility, and robustness. Results: Limit of detection (LOD) and limit of quantification (LOQ) were for all substances determined lower than 50 and 100 ng/L, respectively. Average relative standard deviations below 5% were achieved for all analytes, with recovery rates ranging between 93% and 101%. Subsequently, the method was applied for the determination of BTEX in one hundred groundwater samples. The findings revealed that the BTEX levels were below the LOD in 84.2% of samples. However, in the remaining samples, more than one compound was detected at concentrations higher than the LOQ. Conclusions: The ITEX method emerges as a highly favorable alternative to both solid phase microextraction (SPME) and purge and trap (P & T) methods for determining BTEX in aqueous samples, providing significant advantages. Its strengths lie in its increased robustness, extended trap lifespan, and enhanced sensitivity, underscoring its superior performance in VOC analysis. The total analytical method allows the sensitive and robust determination of VOC.

In this article, the concentration of some volatile organic compounds (VOCs) in the hot oil sample of the Pars petrochemical ethylbenzene unit is presented. Pars Petrochemical is one of the largest producers of ethylbenzene in the Middle East. The hot oil impurities that were analyzed were benzene and toluene (BT). The hot oil sample was taken in May 2023 at a special sampling station on the site. The presence of BT is related to its intensity in the hot oil sample. The Multiple Headspace Extraction (MHE) method was used for the extraction and quantitative analysis of BT followed by gas chromatography (GC) analysis. A GC with flame ionization detector (FID) instrument was used for the analysis of BT. This method offers advantages for the analysis of volatile pollutants because it eliminates the use of organic solvents and various sample purification steps that often lead to erroneous results. The MHE method is independent of standard concentration and could be used in a wide range of BT in Hot Oil without calibration for different ranges. Also, linearity, detection limits, and accuracy were looked into as part of the validation process. The limit of detection (LOD) and limit of quantification (LOQ), respectively, were between 0.05 - 0.56, and 0.17 - 1.9 mg/kg. Less than 13.95 percent (n= 15) was the relative standard deviation statistically. A quick and easy method for detecting BT in hot oil samples was used for the first time. This work will be a step forward for the detection of other aromatic and cyclic hydrocarbons in hot oil samples.

The purpose of this study was to assess the concentrations of persistent organic pollutants in the White Drin River, Kosovo region. The study focused on organochlorine pesticides, polychlorinated biphenyls, polycyclic aromatic hydrocarbons, and benzene, toluene, ethylbenzene, and xylenes. The White Drin River originates from Peja, Kosovo, and extends to the Albanian border near Kukesi, making it a significant water body. It is potentially affected by anthropogenic pollution due to its passage through Kosovo’s urban areas, villages, farms, and industries. Sampling was conducted at 15 stations along the river, from the river waterfall to the Albanian border, during two distinct periods in 2023 (January – February and August – September). Organochlorine pollutants were concurrently extracted using liquid-liquid extraction followed by analysis using capillary gas chromatography equipped with an electron capture detector. Polycyclic aromatic hydrocarbons were isolated through a two-step liquid-liquid extraction, with dichloromethane and hexane. Benzene, toluene, ethylbenzene, and xylenes were isolated using headspace solid – phase microextraction assisted by polydimethylsiloxane fibre. Qualitative and quantitative analyses of polycyclic aromatic hydrocarbons, and benzene, toluene, ethylbenzene, and xylenes, were conducted via gas chromatography with a flame ionization detector. The analyses showed the presence of persistent organic pollutants in the river water samples during both sampling periods. Elevated concentrations of volatile polychlorinated biphenyls, benzene, toluene, ethylbenzene, and xylenes, and polycyclic aromatic hydrocarbons, were observed in the water samples during both periods. This study underscores the significance of investigating organic pollutants in Kosovo’s water systems, considering both local geographic concerns and the broader global issue of environmental pollution

Zeolites are widely used for removing volatile organic compounds (VOCs) in industrial processes. However, the understanding of the competitive adsorption behavior of multicomponent VOCs on zeolites remains insufficient. This study employed grand canonical Monte Carlo simulation to investigate the adsorption behaviors of nonpolar benzene and polar ethyl acetate in both pure and mixed forms on FAU, LTA and MFI zeolites. The effects of zeolite topology, Si/Al ratio, and compensating cations on competitive adsorption were explored. The results revealed that the adsorption capacities of benzene and ethyl acetate on FAU and LTA zeolites gradually increased with increasing Si/Al ratio, consistent with the increasing trends in their specific surface areas and pore volumes. However, the MFI zeolite shows no significant change in these properties with varying Si/Al ratios. Zeolites modified with Ca2+ significantly improved the benzene and ethyl acetate adsorption capacities, while impact on ethyl acetate adsorption is minimal. Zeolites modified with K+ reduced the adsorption capacities for both benzene and ethyl acetate. For binary mixtures, Na-FAU-1, Na-LTA-1, and Na-MFI-15 exhibited high selectivity for ethyl acetate. Increasing the Si/Al ratio and K+-modification reduced the adsorption selectivity of these zeolites for ethyl acetate. Ca2+-modification reduces the selectivity of LTA-1 toward ethyl acetate, with minimal impact on FAU-1 and MFI-15. Dynamic adsorption experiments with commercial zeolites confirm the reliability of the simulation results in predicting benzene and ethyl acetate adsorption performance. This study is expected to provide guidance for selecting appropriate zeolites for VOCs mixtures in practical applications. [ABSTRACT FROM AUTHOR]

Copyright of China Synthetic Fiber Industry is the property of Sinopec Baling Petrochemical Company and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Gracilaria sp. is a red macro-alga isolated from the marine environment of the Red Sea in Egypt. Unfortunately, this alga has not been well exploited yet in Egypt, thus the author preferred to highlight the economic importance of this alga. In this study, the chemical composition of the edible red seaweed Gracilaria sp. was evaluated via quantitative and qualitative tests using distilled water and two solvents (ethyl acetate and benzene) different in their polarity. The results showed that Gracilaria sp. contains a protein content of 22.75 %, fat of 1.01%, carbohydrate of 37.58% on dry weight basis, as well as pigments such as phycoerythrin, phycocyanin, allophycocyanin, β-carotene and chlorophyll a with yields of 3.8± 1.3, 1.8± 0.7, 0.9± 0.6, 7.7± 1.4, 1.6± 1.5mg/ ml D.W., respectively. Moroever, polysaccharide agar had a yield of 23.93% and total phenolic compounds of 54.5mg GAE/ g extract. Tests of the chemical composition of this alga showed the availability of many chemical compounds that have great economic importance in the field of medicine, pharmaceuticals, cosmetics, and food industries as an antioxidant IC50 27 ± 1.68mg/ ml, a bactericidal and fungicidal agent and as a bio pesticide in the field of agriculture. Egypt should also benefit from polysaccharide agar from Gracilaria sp. in biotechnology laboratories as growth media for bacteria, yeast, and fungi as well as the use of Gracilaria sp. pigments in the food and cosmetic industries as good natural colors. [ABSTRACT FROM AUTHOR]

In this work, the precursors and intermediates of catalytic dehydrogenation of toluene, ethylbenzene, and styrene (TES) stream were detected, quantified, and classified at 750–800 °C. The classification approach for tracing the structural changes of the produced precursors was designed based on different residence times of intermediates, leading to the presentation of a morphology prediction model for precipitated coke according to the restriction of stream pass. The results revealed that the coke structure of encapsulating is formed by heavier precursors produced at a restricted direction of flow. On the other hand, the filamentous coke made from lighter precursors is formed at smooth streams with no restricted areas. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Air Pollution & Health is the property of Tehran University of Medical Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study examined the artificial neural network (ANN) modeling of simultaneous biofiltration of methane (CH4) with two volatile organic compounds (VOCs): xylene and ethylbenzene, using an inorganic packed bed biofilter at an empty bed residence time (EBRT) of 4.5 min. Results showed that the removal efficiency (RE) of CH4 was in the range of 50 to 60% for concentrations of 1000 to 10,000 ppmv (0.6 to 6.5 g m−3), while the VOCs-REs were between 70 and 90% for X and EB concentrations in the range of 200 to 500 ppmv (0.9 to 2.2 g m−3). Artificial neural networks were used to predict and simulate the performances of the biofilter, based on a database containing previous biofiltration works. The ANN1 (architecture of 3 (input layer)-18 (hidden layer)-1 (output layer)) accurately predicted CH4 conversion at the pseudo-steadystate condition, while the ANN2 (4 (input layer)-18 (hidden layer)-2 (output layer)) predicted the simultaneous conversion of CH4 and VOCs with slightly lower accuracy than ANN1. The ANN3 (4 (input layer)-30 (hidden layer)-1 (output layer)) successfully predicted the acclimation period and final phase (CH4 concentration of 10,000 ppmv) of the biofilter but could not accurately predict the transient phases and showed differences (up to 20%) from experimental results once the CH4 concentration was changed. This study developed a decision support and prediction tool to anticipate the performance of biofilters in treating residual gases containing CH4 and VOCs, avoiding costs and delays associated with experimentation. [ABSTRACT FROM AUTHOR]

A series of mesoporous ceria-supported vanadium oxide catalysts were prepared and explored for aerobic oxidation of ethylbenzene to acetophenone without the involvement of any solvent or additive. Catalysts with varying contents of V2O5 (3, 6, and 10 wt%) on a mesoporous CeO2 support were prepared by the wet-impregnation method. Catalysts were characterized using techniques namely, XRD, Raman spectroscopy, BET surface area analysis, ICP-OES, FE-SEM, HR-TEM, XPS, and H2-TPR to establish a correlation between the physicochemical properties and catalytic performance. Among the investigated catalysts, the catalyst with 6 wt% of V2O5 on mesoporous ceria showed better activity with 69% ethylbenzene conversion and 88% acetophenone selectivity. The superior activity of this catalyst was ascribed to a strong synergetic interaction between ceria and vanadia as well as the formation of a CeVO4 phase, and a high specific surface area. The reaction parameters like temperature, pressure, and the amount of catalyst were optimized for possible commercial utilization. The stability of the catalyst was also investigated by the reusability test and was found to be stable and active up to five cycles. [ABSTRACT FROM AUTHOR]

In recent years, there has been a growing interest in developing portable and personal devices for measuring air quality and surrounding pollutants, partly due to the need for ventilation in the aftermath of COVID-19 situation. Moreover, the monitoring of hazardous chemical agents is a focus for ensuring compliance with safety standards and is an indispensable component in safeguarding human welfare. Air quality measurement is conducted by public institutions with high precision but costly equipment, which requires constant calibration and maintenance by highly qualified personnel for its proper operation. Such devices, used as reference stations, have a low spatial resolution since, due to their high cost, they are usually located in a few fixed places in the city or region to be studied. However, they also have a low temporal resolution, providing few samples per hour. To overcome these drawbacks and to provide people with personalized and up-to-date air quality information, a personal device (smartwatch) based on MEMS gas sensors has been developed. The methodology followed to validate the performance of the prototype was as follows: firstly, the detection capability was tested by measuring carbon dioxide and methane at different concentrations, resulting in low detection limits; secondly, several experiments were performed to test the discrimination capability against gases such as toluene, xylene, and ethylbenzene. principal component analysis of the data showed good separation and discrimination between the gases measured. [ABSTRACT FROM AUTHOR]

Cyclooctene and alkylbenzenes are subjected to co-oxidation in oxygen and a system of two catalysts. Radical catalyst Fe(acac)3/NHPI mediates the formation of alkylbenzene hydroperoxides, which are consumed in situ during the MoO3/SiO2-catalyzed epoxidation of cyclooctene. The chain oxidation rate is limited in cyclooctene and MoO3/SiO2, but radical catalyst Fe(acac)3/NHPI retains fairly high activity in the oxidation of alkylbenzene in hydroperoxide. It is found that isopropylbenzene is a better co-reducing agent than ethylbenzene because it ensures more vigorous and selective formation of epoxycyclooctane. At optimized amounts of components and a temperature of 80°C, selectivity toward epoxycyclooctane reaches 92 and 96% in ethylbenzene or isopropylbenzene, respectively, with more than 70% conversion of cyclooctene. [ABSTRACT FROM AUTHOR]

The purpose of this study was to assess the concentrations of persistent organic pollutants in the White Drin River, Kosovo region. The study focused on organochlorine pesticides, polychlorinated biphenyls, polycyclic aromatic hydrocarbons, and benzene, toluene, ethylbenzene, and xylenes. The White Drin River originates from Peja, Kosovo, and extends to the Albanian border near Kukesi, making it a significant water body. It is potentially affected by anthropogenic pollution due to its passage through Kosovo's urban areas, villages, farms, and industries. Sampling was conducted at 15 stations along the river, from the river waterfall to the Albanian border, during two distinct periods in 2023 (January - February and August - September). Organochlorine pollutants were concurrently extracted using liquid-liquid extraction followed by analysis using capillary gas chromatography equipped with an electron capture detector. Polycyclic aromatic hydrocarbons were isolated through a two-step liquid-liquid extraction, with dichloromethane and hexane. Benzene, toluene, ethylbenzene, and xylenes were isolated using headspace solid - phase microextraction assisted by polydimethylsiloxane fibre. Qualitative and quantitative analyses of polycyclic aromatic hydrocarbons, and benzene, toluene, ethylbenzene, and xylenes, were conducted via gas chromatography with a flame ionization detector. The analyses showed the presence of persistent organic pollutants in the river water samples during both sampling periods. Elevated concentrations of volatile polychlorinated biphenyls, benzene, toluene, ethylbenzene, and xylenes, and polycyclic aromatic hydrocarbons, were observed in the water samples during both periods. This study underscores the significance of investigating organic pollutants in Kosovo's water systems, considering both local geographic concerns and the broader global issue of environmental pollution. [ABSTRACT FROM AUTHOR]

BTEX is a group of hazardous chemical compounds that include benzene, toluene, ethylbenzene, and xylene. The indoor concentration of BTEX is mostly influenced by tobacco smoking, the region within the house, and seasonal variations. This study included three databases: "Google Scholar", "Science Direct", and "Springer". Out of the 1351 articles obtained from the keyword search, only 13 were eventually selected for this study. The most abundant compound found in houses among BTEX was toluene, with a concentration of 13.80±16.50 µg/m3. The results indicated that the concentration of benzene in houses where smoking occurred was greater than in houses where no smoking occurred (7.17±9.42 vs. 2.65±3.77 µg/m3, unpaired Wilcoxon test: p>0.05). The concentration of BTEX in houses was substantially lower than that in cafes (21.10±31.10 vs. 15,100±9740 µg/m3, unpaired Wilcoxon test: p 0.05). The findings indicated that the cancer risk (CR) associated with houses (3.11×10-6) and cafes (3.54×10-3) exceeded the permissible threshold. Moreover, the waterpipe cafes that utilized fruit-flavored tobacco had the greatest CR (4.98×10-3). Furthermore, the presence of smoking, regional factors, and seasonal variations did not result in an increase in the hazard quotient (HQ) in houses beyond the acceptable thresholds.

The ethylene dehydrogenation catalyst in a certain styrene unit was caked after long-term use. In order to analyze the caking cause of ethylbenzene dehydrogenation catalyst, solubility experiment, baking experiment and X-ray fluorescence spectrum test were carried out. The experimental results showed that the white solid on the surface of the caking catalyst could be dissolved in the water. After the caking catalyst was roasted at 800 °C for 4 h, the white substance was existed. The small granular particles were not crushed easily and were hard. The X-ray fluorescence spectrometer test showed that the white solid was a potassium-containing substance on the catalyst surface. The block formation of the ethylbenzene dehydrogenation catalyst in this unit is caused by the migration and aggregation of potassium during long-term use of the catalyst. The research provided some technical reference for reducing the caking of ethylbenzene dehydrogenation catalyst in the production. [ABSTRACT FROM AUTHOR]

Density and viscosity values of the binary mixture of ethylbenzene and aniline have been experimentally measured in different mole fractions at temperatures of 293.15 to 313.15 K and at an absolute pressure of 86.7 kPa. Based on the obtained experimental data, the excess molar volume and viscosity deviations have been reported, which can interpret the interactions in this mixture. The obtained data were fitted with the Redlich‐Kister equation. In addition, the viscosity results are discussed using the equation proposed by Gruenberg‐Nissan. After experimental studies, in order to investigate the interactions of these two components and their mixture, quantum mechanical calculations and molecular dynamics simulation have been used. In this way, the structures of the desired molecules have been optimized. Then Atoms in Molecules (AIM) and frontier molecular orbital (FMO) techniques have been used for a more detailed investigation. Finally, by plotting radial distribution functions (RDFs) obtained from molecular dynamics, these interactions have been investigated in a more comprehensive way. In addition, the simulated densities at 298.15 K have been reported. At the end, clear pictures of the interactions of molecules in mixtures were obtained by comparing the achievements of experimental measurements, quantum chemical and calculations MD simulation. [ABSTRACT FROM AUTHOR]

The densities (ρ), and ultrasonic speeds (u) of pure ethyl benzene, 1-butanol, 1-pentanol, and those of their binary mixtures, with ethyl benzene as a common component, covering the whole composition range have been measured at 298.15, 303.15, 308.15, 313.15, 318.15 and 323.15 K. From the experimental data the excess molar volume (VmE), deviations in isentropic compressibility (ΔKs) and deviations in ultrasonic speed (Δu) have been determined. The sign and magnitude of these parameters were found to be sensitive towards interactions prevailing in the studied systems. The excess or deviation properties (VmE, Δu, or ΔKs) have been correlated using a Redlich-Kister type equation to obtain their coefficients and standard deviations. The variations of derived parameters mentioned above with composition offer a convenient method to study the nature and extent of interactions between the component molecules of the liquid mixtures, which are not easily obtained by other means. [ABSTRACT FROM AUTHOR]

Utilizing carbon dioxide as a carbon source for the synthesis of olefins and aromatics has emerged as one of the most practical methods for CO2 reduction. In this study, an improved selectivity of 85% for targeting products (ethylbenzene and propylbenzene) is achieved with a benzene conversion of 16.8% by coupling the hydrogenation of carbon dioxide to olefins over the bifunctional catalyst "Oxide-Zeolite" (OX-ZEO) and the alkylation of benzene with olefins over ZSM-5. In addition to investigating the influence of SAPO-34 and ZSM-5 zeolite acidity on product distribution, catalyst deactivation due to coke formation is addressed by modifying both molecular sieves to be hierarchical to extend the catalyst lifespan. Even after 100 h of operation at 400 °C, the catalysts maintained over 80% selectivity towards the target products, with benzene conversion over 14.2%. Furthermore, the pathway of propylbenzene formation is demonstrated through simple experimental design, revealing that the surface Brønsted acid sites of SAPO-34 serve as its primary formation sites. This provides a novel perspective for further investigation of the reaction network. [ABSTRACT FROM AUTHOR]

A rapid and mild coating strategy was applied on the millimeter scale calcium alginate capsules (Ca‐SA caps) by in situ interfacial polymerization of ethyl cyanoacrylate (ECA). The generated poly(ethyl cyanoacrylate) (PECA) coating was initiated by trace water in the surface of the Ca‐SA caps. The effects of ECA content, reaction time, and type of aromatic solvent on the morphology and control‐release property of the resulting PECA‐coated Ca‐SA caps (Ca‐SA caps@PECA) were investigated. The results demonstrated a white PECA layer successfully coated on the surface of Ca‐SA caps. Notably, the Ca‐SA caps@PECA remained consistently pleasing spherical shape as prepared in methylbenzene and ethylbenzene. When the ECA was 6 mL, the thickness of PECA layer of the Ca‐SA caps@PECA was 43.52 μm. Compared with the Ca‐SA caps, the weight retention ratio of water in the Ca‐SA caps@PECA increased by 254.61%, indicating the effective delay of water diffusion from core of the Ca‐SA caps@PECA. Moreover, the PECA coating improved the stability of the Ca‐SA caps@PECA, which achieved release‐controlling of dye at different pH. This method provides solution for surface modification of fragile hydrogel capsules to effectively control the releasing of liquid core, which is highly valuable in the field of food, cosmetic, and medical delivery. [ABSTRACT FROM AUTHOR]

The development of highly active and selective photocatalytic systems for the oxidation of benzylic C(sp3)–H and C(sp3)–OH to C＝O bonds under solvent-free conditions with molecular oxygen as an oxidant is attractive and challenging. In this study, a carbon- and PdO-doped Nb2O5-based catalyst (PdO/C–Nb2O5) was designed and synthesized. This photocatalyst showed excellent solvent-free aerobic photocatalytic performances for two typical oxidation reactions of benzylic C(sp3)–H and C(sp3)–OH to C＝O compounds. It was found that the doping of carbon and PdO in Nb2O5 can modify its surface electrons, increase oxygen vacancies, and change the positions of its valence band and conduction band. Besides, the kinetic study showed that the oxidation of C–H in ethylbenzene to C–OH is the rate-limiting step in the two-step oxidation of ethylbenzene to acetophenone. Moreover, a photocatalytic reaction mechanism was proposed based on these experiments. In addition, the solvent-free aerobic photocatalytic oxidation system showed a good substrate tolerance for benzylic C(sp3)–H and C(sp3)–OH compounds with different substituents to the corresponding ketones and aldehydes. [ABSTRACT FROM AUTHOR]

• PdPtV nanoparticles (NPs) are synthesized using the oil-phase co-reduction strategy. • The PdPtV/CeO 2 −ZrO 2 catalyst performs the best in ethylbenzene (EB) oxidation. • PdPtV/CeO 2 −ZrO 2 shows large EB adsorption capacity, good reducibility, and strong surface acidity. • TPD and in situ DRIFTS are used to study the reversible poisoning of PdPtV/CeO 2 −ZrO 2 by SO 2. • V doping to PdPt NPs protects the active PdPt sites from being poisoned by SO 2. The PdPtVO x /CeO 2 −ZrO 2 (PdPtVO x /CZO) catalysts were obtained by using different approaches, and their physical and chemical properties were determined by various techniques. Catalytic activities of these materials in the presence of H 2 O or SO 2 were evaluated for the oxidation of ethylbenzene (EB). The PdPtVO x /CZO sample exhibited high catalytic activity, good hydrothermal stability, and reversible sulfur dioxide-poisoning performance, over which the specific reaction rate at 160°C, turnover frequency at 160°C (TOF Pd or Pt), and apparent activation energy were 72.6 mmol/(g Pt ⋅sec) or 124.2 mmol/(g Pd ⋅sec), 14.2 sec−1 (TOF Pt) or 13.1 sec−1 (TOF Pd), and 58 kJ/mol, respectively. The large EB adsorption capacity, good reducibility, and strong acidity contributed to the good catalytic performance of PdPtVO x /CZO. Catalytic activity of PdPtVO x /CZO decreased when 50 ppm SO 2 or (1.0 vol.% H 2 O + 50 ppm SO 2) was added to the feedstock, but was gradually restored to its initial level after the SO 2 was cut off. The good reversible sulfur dioxide-resistant performance of PdPtVO x /CZO was associated with the facts: (i) the introduction of SO 2 leads to an increase in surface acidity; (ii) V can adsorb and activate SO 2 , thus accelerating formation of the SO x 2− (x = 3 or 4) species at the V and CZO sites, weakening the adsorption of sulfur species at the PdPt active sites, and hence protecting the PdPt active sites to be not poisoned by SO 2. EB oxidation over PdPtVO x /CZO might take place via the route of EB → styrene → phenyl methyl ketone → benzaldehyde → benzoic acid → maleic anhydride → CO 2 and H 2 O. [Display omitted] [ABSTRACT FROM AUTHOR]

Occupational health risk assessments of exposure to VOCs still need to be extensively studied to improve the safety standards in the industry. Based on the monitoring of organic pollutants at various workstations in a truck tire factory in Jiangsu Province, both semi-quantitative and quantitative health risk assessment methods were employed to assess health risk levels. The findings indicated that VOCs were categorized into five classes, which included alkanes, aromatics, halocarbons, carbon disulfide, and oxygenated volatile organic compounds (OVOCs). The highest concentration of total volatile organic compounds (TVOCs) was found in shaping workshop; alkanes were the most abundant class (74.2%), followed by aromatics (24.02%) and OVOCs (1.96%). Although the results of the semi-quantitative risk assessment showed that most of the organic compounds had low R values, various kinds of VOCs were detected; particularly, many harmful organic compounds (such as toluene, ethyl benzene) were detected in all the sampling sites. The quantitative risk in the calendering and vulcanizing workshop exceeded the acceptable level; both the carcinogenic risk of ethylbenzene in the tire-strip storage room, and trichloroethylene and perchloroethylene in the calendering workshop were unacceptable. Thus, the calendering and vulcanizing processes in rubber tire manufacturing should be priority-controlled processes. [ABSTRACT FROM AUTHOR]

A rapid increase in viscosity during the polymerization process impacts the polymerization rate. To address this issue, ethylbenzene is often introduced into the polymerization system in order to reduce viscosity. The thermal characteristics of styrene–ethylbenzene polymerization have been identified using differential scanning calorimetry. The rate of heat generation significantly decreases as the proportion of ethylbenzene increases. The polymerization product mixtures were analyzed using gel permeation chromatography. Polymerization at low viscosity yields a higher proportion of low molecular mass polymers and a more uniform distribution of product chain lengths compared to polymerization at high viscosities. The glass transition temperature and the activation energy for viscous flow of the products were also determined. The apparent kinetics of styrene polymerization may be described using the "autocatalytic + Nth-order" model. Two stages of monomer conversion are apparent: polymerization reactions initiated by AIBN and thermally induced polymerization. Valuable insights into the polymerization process which can contribute to the optimization of industrial polymerization reactions have been obtained. [ABSTRACT FROM AUTHOR]

Herein, it is aimed to investigate the effect of zeolite catalyst on the co‐pyrolysis process of waste tyre and poplar wood. A laboratory‐sized reactor is used to pyrolyze 15 g of sample at 500 °C under atmospheric pressure. In the results, it is indicated that co‐pyrolysis affects the properties of the products. Comparing to single feedstock, the co‐pyrolysis enhances the yields of bio‐oil, while reducing the formation of char. The pyrolysis of poplar wood produces 23.3 wt% of bio‐oil, while the pyrolysis of tyre yields 25 wt% of bio‐oil. However, it is 31.29 wt% for the co‐pyrolysis process. Higher content of valuable compounds are formed in the bio‐oil, which improve the fuel properties of the bio‐oil. The zeolite catalyst alters the characteristics of the products obtained from the co‐pyrolysis process. The gaseous products show a decrease in the concentrations of carbon monoxide and carbon dioxide when the catalyst is present. The liquid product analysis reveals the presence of light aromatics such as ethyl benzene and light linear compounds such as alkanes including octane, hexane, etc. The analysis of the catalysts suggests that a very small amount of coke deposits on the catalyst due to the slight increase in carbon content. [ABSTRACT FROM AUTHOR]

Large volumes of wastewater are generated during petroleum refining processes. Petroleum refinery wastewater (PRW) can contain highly toxic compounds that can harm the environment. These toxic compounds can be a challenge in biological treatment technologies due to the effects of these compounds on microorganisms. These challenges can be overcome by using ozone (O3) as a standalone or as a pretreatment to the biological treatment. Ozone was used in this study to degrade the organic pollutants in the heavily contaminated PRW from a refinery in Mpumalanga province of South Africa. The objective was achieved by treating the raw PRW using ozone at different ozone treatment times (15, 30, 45, and 60 min) at a fixed ozone concentration of 3.53 mg/dm3. The ozone treatment was carried out in a 2-liter custom-designed plexiglass cylindrical reactor. Ozone was generated from an Eco-Lab-24 corona discharge ozone generator using clean, dry air from the Afrox air cylinder as feed. The chemical oxygen demand, gas chromatograph characterization, and pH analysis were performed on the pretreated and post-treated PRW samples to ascertain the impact of the ozone treatment. The ozone treatment was effective in reducing the benzene, toluene, ethylbenzene, and xylenes (BTEX) compounds in the PRW. The 60-min ozone treatment of different BTEX pollutants in the PRW resulted in the following percentage reduction: benzene 95%, toluene 77%, m + p-xylene 70%, ethylbenzene 69%, and o-xylene 65%. This study has shown the success of using ozone in reducing the toxic BTEX compounds in a heavily contaminated PRW. [ABSTRACT FROM AUTHOR]

Introduction: Considering the adverse carcinogenic and non-carcinogenic health effects of Volatile Organic Compounds (VOC) and specially Benzene, Toluene, Ethylbenzene and Xylenes (BTEX) which are widely used in vehicle manufacturing industry, it is clear that monitoring and control of occupational exposure to these substances is of utmost significance. More often than not the studies on occupational exposure to VOCs in vehicle manufacturing industry—specifically BTEX—have been carried out exclusively in paint shop units. The purpose of this study was to assess occupational BTEX exposure & health risk in different units of a vehicle manufacturing industry. Material and methods: Foam injection unit (FIU), gluing unit (GU), repair shop unit (RSU), molding unit (MU) as well as paint shop units (PSU) were selected for this study. Sampling and analysis were conducted based on National Institute for Occupational Safety and Health (NIOSH) 1501 guidelines by utilizing MSA personal sampling pumps set to 0.2 l/m and Gas Chromatography equipped with Flame Ionization Detector (GC-FID). Risk characterization and assessment was performed using Environmental Protection Agency Risk Assessment Information System (EPA RAIS). Results and conclusion: The results revealed that the concentration of benzene in gluing and paint shop units was above occupational exposure limits. Carcinogenic risk levels in 8 out of 10 units registered in the 1E-2 to 1E-4 range, and only two units registered a risk level below EPA's acceptable risk level (10–6). The highest risk levels were measured in gluing, paint shop and repair shop units. Furthermore, the total non-carcinogenic hazard quotient was measured higher than 1 in 8 out of 10 studied units. Considering the abundance and wide use of VOCs -most notably BTEX- and the adverse carcinogenic and non-carcinogenic health effects of these compounds, it is advised to: change the type of paint used in paint shops, improve the existing ventilation systems, develop new and more efficient ventilation systems and conduct consistent training. Highlights: In this paper, we report on the levels of occupational exposure workers encounter on a daily basis to a specific group of Volatile Organic Compounds (VOC): Benzene, Toluene, Ethylbenzene and Xylene(s) (BTEX) in various sections of a vehicle manufacturing industry and the resulting health risks. Reviewing previous studies revealed that as a result of low occupational exposure to BTEX in vehicle manufacturing industry, more often than not the studies on said compounds and the ensuing health effects were exclusively carried out in paint shop units, ignoring health risks in other units & creating the assumption that health risks in other units are negligible. The purpose of this study was to assess occupational BTEX exposure and its associated health risk in different units of a vehicle manufacturing industry, including foam injection unit (FIU), gluing unit (GU), repair shop unit (RSU), molding unit (MU) as well as paint shop units (PSU). Revealing the possibility of exposure to BTEX not only in paint shop units but also other previously disregarded units, the health risk calculated in some units such as gluing unit was higher than the EPA acceptable risk range (10-4). Moreover, cancer risk levels of molding (Unit No 6) and repair shop (Unit No 7) units registered in the 10-4 to 10-2 range despite meeting the TLV-TWA (0.174 PPM and 0.449 PPM respectively), suggesting the need for implementation of a health risk assessment in conjunction with exposure assessment. [ABSTRACT FROM AUTHOR]

Mandatory use of low-sulfur fuel according to global sulfur limit regulation has reduced the emissions of SO2 and PM significantly on ships, while it also leads to very large uncertainty on VOCs emission. Therefore, on-board test of VOCs from 9 typical cargo ships with low-sulfur fuels in China were carried out in this study. Results showed that emission factor of VOCs (EFVOCs) varied largely from 0.09 to 3.01 g kg-1 fuel, with domestic coastal cargo ships (CCSs) had the highest levels and ocean-going vessels (OGVs) the lowest. The switch of fuels from heavy fuel oil (HFO) to diesel increased EFVOCs by 48 % on average, which enhanced both O3 and secondary organic aerosol (SOA) formation potentials, especially for OGVs. Besides, the use of low-sulfur fuels for OGVs also lead to significant increase of naphthalene emission. These indicated the implementation of globally ultra-low-sulfur oil policy in the near future needs to be optimized. Moreover, aromatics were the most important common contributors to O3 and SOA in ship exhausts, which need to be controlled with priority. It was also found that benzene, toluene, and ethylbenzene ratio of 0.5:0.3:0.2 on average could be considered as a diagnostic characteristic to distinguish ship emission from other emission sources. [ABSTRACT FROM AUTHOR]

Production of commodity chemicals, such as benzene, toluene, ethylbenzene, and xylenes (BTEX), from renewable resources is key for a sustainable society. Biocatalysis enables one‐pot multistep transformation of bioresources under mild conditions, yet it is often limited to biochemicals. Herein, we developed a non‐natural three‐enzyme cascade for one‐pot conversion of biobased l‐phenylalanine into ethylbenzene. The key rate‐limiting photodecarboxylase was subjected to structure‐guided semirational engineering, and a triple mutant CvFAP(Y466T/P460A/G462I) was obtained with a 6.3‐fold higher productivity. With this improved photodecarboxylase, an optimized two‐cell sequential process was developed to convert l‐phenylalanine into ethylbenzene with 82 % conversion. The cascade reaction was integrated with fermentation to achieve the one‐pot bioproduction of ethylbenzene from biobased glycerol, demonstrating the potential of cascade biocatalysis plus enzyme engineering for the production of biobased commodity chemicals. [ABSTRACT FROM AUTHOR]

This study aimed to examine the impacts of single and multiple air pollutants (AP) on the severity of breast cancer (BC). Data of 1148 diagnosed BC cases (2008–2016) were obtained from the Cancer Research Center and private oncologist offices in Tehran, Iran. Ambient PM10, SO2, NO, NO2, NOX, benzene, toluene, ethylbenzene, m-xylene, p-xylene, o-xylene, and BTEX data were obtained from previously developed land use regression models. Associations between pollutants and stage of BC were assessed by multinomial logistic regression models. An increase of 10 μg/m3 in ethylbenzene, o-xylene, m-xylene, and 10 ppb of NO corresponded to 10.41 (95% CI 1.32–82.41), 4.07 (1.46–11.33), 2.89 (1.08–7.73) and 1.08 (1.00–1.15) increase in the odds of stage I versus non-invasive BC, respectively. Benzene (OR, odds ratio = 1.16, 95% CI 1.01–1.33) and o-xylene (OR = 1.18, 1.02–1.38) were associated with increased odds of incidence of BC stages III & IV versus non-invasive stages. BC stage I and stage III&IV in women living in low SES areas was associated with significantly higher levels of benzene, ethylbenzene, o-xylene, and m-xylene. The highest multiple-air-pollutants quartile was associated with a higher odds of stage I BC (OR = 3.16) in patients under 50 years old. This study provides evidence that exposure to AP is associated with increased BC stage at diagnosis, especially under premenopause age. [ABSTRACT FROM AUTHOR]

A comprehensive density functional theory investigation has been presented towards the comparison of the C–H activation reactivity between high-valent iron-oxo and ruthenium-oxo complexes. A total of four compounds, e.g., [Ru(IV)O(tpy-dcbpy)] (1), [Fe(IV)O(tpy-dcbpy)] (1′), [Ru(IV)O(TMCS)] (2), and [Fe(IV)O(TMCS)] (2′), have been considered for this investigation. The macrocyclic ligand framework tpy(dcbpy) implies tpy = 2,2′:6′,2′′-terpyridine, dcbpy = 5,5′-dicarboxy-2,2′-bipyridine, and TMCS is TMC with an axially tethered –SCH2CH2 group. Compounds 1 and 2′ are experimentally synthesized standard complexes with Ru and Fe, whereas compounds 1′ and 2 were considered to keep the macrocycle intact when switching the central metal atom. Three reactants including benzyl alcohol, ethyl benzene, and dihydroanthracene were selected as substrates for C–H activation. It is noteworthy to mention that Fe(IV)O complexes exhibit higher reactivity than those of their Ru(IV)O counterparts. Furthermore, regardless of the central metal, the complex featuring a tpy-dcbpy macrocycle demonstrates higher reactivity than that of TMCS. Here, a thorough analysis of the reactivity-controlling characteristics—such as spin state, steric factor, distortion energy, energy of the electron acceptor orbital, and quantum mechanical tunneling—was conducted. Fe(IV)O exhibits the exchanged enhanced two-state-reactivity with the quintet reactive state, whereas Ru(IV)O has only a triplet reactive state. Both the distortion energy and acceptor orbital energy are low in the case of Fe(IV)O supporting its higher reactivity. All the investigated C–H activation processes involve a significant contribution from hydrogen tunneling, which is more pronounced in the case of Ru, although it cannot alter the reactivity pattern. Furthermore, it has also been found that, independent of the central metal, aliphatic hydroxylation is always preferable to aromatic hydroxylation. Overall, this work is successful in establishing and investigating the cause of enzymes' natural preference for Fe over Ru as a cofactor for C–H activation enzymes. [ABSTRACT FROM AUTHOR]

In ethylbenzene dehydrogenation process, the produced coke is the main source of catalyst deactivation, deterioration of stainless steel piping (carburization) and the flow pass plugging. The novelty of this work is determination, ranking and modeling of influencing factors and their interactions on the rate of coke formation in ethylbenzene dehydrogenation process including independent parameters such as styrene and toluene concentrations, surface temperature, the reactor shape factor and steam to ethylbenzene (St/EB) weight ratio. A laboratory setup was used to investigate the effect of above listed parameters and the response surface methodology (RSM) was used to analyze the experiments and optimize the parameters. The ANOVA results illustrated that the model is significant and able to predict coke. The p-values for all parameters are less than 0.05, indicating these parameters are effective factors on coke formation. The results revealed that by increasing styrene and toluene concentrations and surface temperature, the rate of coke formation increases. In such circumstances, surface temperature showed maximum effect due to the increase of cracking reactions and the production of coke precursors such as stilbene, anthracene etc. On the other hand, the effect of St/EB weight ratio on the rate of coke formation is inverse. The results obtained from SEM/EDS analysis showed the filamentous coke forms on the surface of 304 H austenitic steel. [Display omitted] • Styrene and toluene concentrations, surface temperature, shape factor and St/EB ratio were identified as influencing factors on coke formation. • RSM method was used to analyze and optimize the independent parameters on coke formation. • GC and GC-MS were performed to confirm the presence of coke precursors. • EDX spectra revealed the formation of filamentous coke on the surface of austenitic steel. [ABSTRACT FROM AUTHOR]

Styrene polymerization is a strong exothermic reaction, where the reactants, initiators and diluents are flammable and explosive substances. Once the reaction is out of control, it is extremely easy to cause fire and explosion accidents. In order to analyze the thermal hazards of styrene polymerization reactions, the thermal behaviors of reactions at different reaction conditions are investigated in this paper. Differential scanning calorimeter (DSC) and adiabatic rate calorimeter (ARC) were used to study thermal behavior of styrene polymerization reactions initiated by dual initiators (azodiisobutyronitrile/tert-butyl peroxybenzoate) with different ratios. Reaction calorimetric experiments were performed via reaction calorimeter (RC1e) to analyze the process hazard and calculate thermal hazard parameters. Subsequently, the thermal decomposition properties of the polymerization products were studied by simultaneous thermal analyzer (TGA–DSC). Moreover, the apparent activation energy (Ea) during product decomposition was calculated by Starink and Friedman methods. The results show that the presence of initiators increases the risk of thermal runaway of the reaction. The thermal hazard of styrene polymerization can be reduced due to the addition of ethylbenzene. The most serious consequences of thermal runaway were caused at an early stage. It can be concluded that the reaction of the system containing AIBN initiator reacts at a lower temperature, while the reaction of the system with TBPB is relatively lagged. This study is valuable for the selection of initiator in the polymerization reaction process. [ABSTRACT FROM AUTHOR]

The efficient conversion of ethane has attracted more and more attention because of the shale gas revolution. The coupling of ethane dehydrogenation (EDH) and benzene alkylation over the 1.5Pt/HZSM-5 realize high activity close to the thermodynamic equilibrium of EDH at 500 ℃ and 0.9 bar ethane partial pressure. Meanwhile, the coupled reaction shows long-term stability during 22 h with a slightly decreased ethane conversion of 0.03% per hour and as high as 42% selectivity of ethylbenzene. Based on various characterization, including XRD, HR-TEM, NH3-TPD, Py-IR, TGA, it is confirmed that the coupling reaction could convert ethylene, formed by EDH over Pt sites, to ethylbenzene via benzene alkylation over Brönsted acidic sites (BAS) subsequently, and suppressing the sintering of Pt species and coke deposition induced by aromatization and deep dehydrogenation, resulting in high activity and long-time steady state. [ABSTRACT FROM AUTHOR]

One of the steps in scaling the technology for the synthesis of zeolite-containing catalysts from the laboratory to commercial level is support forming. In this study, halloysite nanotubes and aluminum oxide were used as binders for preparing a support based on MFI (ZSM-5) zeolite. The Pt catalysts (Pt/ZSM-5/Al2O3 and Pt/ZSM-5/Hall) were tested in isomerization of the aromatic C8 fraction. The forming of supports influenced not only mechanical but also physicochemical properties of the catalysts. On introducing binders into the catalytic system, the fraction of mesopores in the total pore volume of the supports increased, the acidity of the samples decreased, and the ratio of the amounts of the weak and strong acid sites changed. The use of aluminum oxide and halloysite as binders leads to different pathways of the transformation of the aromatic feedstock. The main side reactions observed in the presence of Pt/ZSM-5/Al2O3 and Pt/ZSM-5/Hall catalysts are hydrocracking of alkylaromatic hydrocarbons and their transalkylation/disproportionation, respectively. The best results were obtained at 380°C and feed space velocity of 6 h–1 with Pt/ZSM-5/Hall: p-/о-xylene ratio 1.05, loss of xylenes 4.31%, and ethylbenzene conversion 34%. [ABSTRACT FROM AUTHOR]

Benzene, toluene, ethyl benzene, and xylene (BTEX) are prevalent pollutants in shoe industry-related workplaces. The aim of this study was to assess exposure to BTEX and their carcinogenic and non-carcinogenic risks in shoe-industry-related workplaces. This study was carried out at different shoe manufactures, small shoe workshop units, shoe markets, and shoe stores in Tabriz, Iran in 2021. Personal inhalation exposure to BTEX was measured using the National Institute for Occupational Safety and Health (NIOSH) 1501 method. Carcinogenic and non-carcinogenic risks due to inhalation exposure to BTEX were estimated by United States Environmental Protection Agency (U.S. EPA) method based on Mont Carlo simulation. Results showed that the concentrations of benzene and toluene were higher than the threshold limit value (TLV) in both gluing and non-gluing units of shoe manufactures. The total carcinogenic risk (TCR) due to exposure to benzene and ethyl benzene was considerable in all shoe industry-related workplaces. Also, the hazard index (HI) as a non-carcinogenic index was higher than standard levels in all shoe industry-related workplaces. Therefore, shoe industry-related workers are at cancer and non-cancer risks due to exposure to BTEX. Prevention measures need to be implemented to reduce the concentration of BTEX in shoe industry-related workplaces. [ABSTRACT FROM AUTHOR]

The kinetically-derived maximal dose (KMD) is defined as the maximal external dose at which kinetics are unchanged relative to lower doses, e.g., doses at which kinetic processes are not saturated. Toxicity produced at doses above the KMD can be qualitatively different from toxicity produced at lower doses. Here, we test the hypothesis that neoplastic lesions reported in the National Toxicology Program's (NTP) rodent cancer bioassay with ethylbenzene are a high-dose phenomenon secondary to saturation of elimination kinetics. To test this, we applied Bayesian modeling on kinetic data for ethylbenzene from rats and humans to estimate the Vmax and Km for the Michaelis–Menten equation that governs the elimination kinetics. Analysis of the Michaelis–Menten elimination curve generated from those Vmax and Km values indicated KMD ranges for venous ethylbenzene of 8–17 mg/L in rats and 10–18 mg/L in humans. Those venous concentrations are produced by inhalation concentrations of around 200 ppm ethylbenzene, which is well above typical human exposures. These KMD estimates support the hypothesis that neoplastic lesions seen in the NTP rodent bioassay occur secondary to saturation of ethylbenzene elimination pathways and are not relevant for human risk assessment. Thus, ethylbenzene does not pose a credible cancer risk to humans under foreseeable exposure conditions. Cancer risk assessments focused on protecting human health should avoid endpoint data from rodents exposed to ethylbenzene above the KMD range and future toxicological testing should focus on doses below the KMD range. [ABSTRACT FROM AUTHOR]

This perspective paper aims to spark a fundamental debate on the key laws that would combine the nano- to micro-scale flow dynamics of resident contaminants in soil systems under supercritical phase-assisted transportation. The rank of supercritical solvents (SCFs) for hazardous polycyclic aromatic hydrocarbons, benzene, toluene, ethylbenzene, and xylenes is deeply discussed beside its confines to meet the current requests of in situ/ex situ fields. The scaling behaviors during soil–pollutants–SCFs interactions are highlighted to underline the hidden laws behind the basic transportation under flooding remediation. A new strategy based on artificial intelligence learning is emphasized with a demonstrative sample to predict the solubility behavior of this kind of contaminants during a spatiotemporal mechanism. This debate illustrates the conjugate experimental and numerical pathways to deal with the complex nano-remediation dynamics and sheds the light on the current trends and future outlook with techno-economic concerns to promote the faith of a clean and sustainable environment. [ABSTRACT FROM AUTHOR]

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The reactions of two complexes [(RNHP)Mn(CO)4] (RNHP=N‐arylated N‐heterocyclic phosphenium) with H2 at elevated pressure (≈4 bar) were studied by NMR spectroscopy. Irradiation with UV light initialized in one case (5 a, R=Dipp) the unselective formation of (RNHP‐H)MnH(CO)4] (6 a) via cooperative addition of H2 across the Mn=P double bond. In the other case (5 b, R=Mes), addition of H2 was unobservable and the reaction proceeded via decarbonylation to a dimeric species [(RNHP)2Mn2(CO)7] (7 b) that was isolated and identified spectroscopically. Taking into account the outcome of further reaction studies under various conditions in the absence and presence of H2, both transformations can be explained in the context of a common mechanism involving decarbonylation to 7 a,b as the first step, and the different outcome is attributable to the fact that 7 b is unreactive towards both H2 and CO while 7 a is not. DFT studies relate this divergence to deviations in the molecular constitution and stability arising from a different level of steric congestion. Preliminary studies suggest further that 5 a/H2 as well as 6 a enable the photo‐induced hydrogenation of styrene to ethyl benzene, even if the mechanism and possibly catalytic nature of this process remain yet unknown. [ABSTRACT FROM AUTHOR]

Anodized TiO2 nanotube fibers using in-headspace solid-phase microextraction (SPME) with gas chromatography-mass spectrometry (GC-MS) have been exploited as an analytical method for volatile organic compounds such as benzene, toluene, ethylbenzene, and xylenes (BTEX) detection. The factors of anodizing time and annealing temperature for TiO2 nanotube production are studied and the adsorption factors (time, ionic strength, and temperature) and desorption factors (time and temperature) for BTEX analysis are optimized. The limit of detections (LODs) for benzene, toluene, ethylbenzene o-xylene, and m, p-xylene are 0.5, 0.1, 1.0, 1.0, and 2.0 µg L-1, respectively. The linear ranges for BTEX (0.5-15,000 µg L-1) and satisfactory linearity (R² ≥ 0.9954) are obtained. This method is successfully applied in real samples with the recoveries ranging from 92% to 97%. TiO2 nanotube fiber is a promising technique for BTEX analysis. [ABSTRACT FROM AUTHOR]

The main objective of this study is to enhance the valuable octane booster aromatics benzene, toluene, and ethylbenzene (BTE) and reduction of styrene in the fuel oil obtained from the pyrolysis of equally mixed waste expanded polystyrene (WEPS) and waste high density polyethylene (WHDPE). This research article, demonstrated the pyrolysis of equally mixed (50 wt.%:50 wt.%) waste expanded polystyrene (WEPS) and waste high-density polyethylene (WHDPE) followed by in situ-hydrogenation and aromatization in a small laboratory scale reactor for the production of value added commodity and gasoline octane boosters mainly benzene, toluene, and ethylbenzene (BTE). Three reactor arrangements i.e., liquid phase/L-type, vapour phase/V-type, and multiphase/M-type were used for conducting the catalytic pyrolysis of feedstock using ZSM-5, ammonium powder as a catalyst. The maximum liquid yield of 87.41 wt.% was obtained for thermal pyrolysis at a temperature of 650°C and at a heating rate of 15°C/min. Whereas, the maximum liquid yield of 82.65 wt.% was obtained for liquid phase/L-type catalytic pyrolysis at a temperature of 600°C, and at a heating rate of 15°C/min. On the other side, vapour phase/V-type and multiphase/M-type catalytic pyrolysis produced a maximum liquid yield of 78.62 wt.% and 74.07 wt.%, respectively at a reaction temperature of 550°C and at the same heating rate. The pyrolysis oil obtained from thermal pyrolysis contained lowest BTE content of 10.43 wt.% and highest styrene content of 66.25 wt.%. Whereas, the highest BTE content of 30.16 wt.% and lowest styrene content of 53.32 wt.% was found in pyrolysis oil obtained from multiphase/M-type catalytic pyrolysis. The quantitative measurement of BTE and styrene content in the pyrolysis oil was made by the gas chromatography (GC) in a flame ionization detector (FID) mode. Graphical Abstract [ABSTRACT FROM AUTHOR]