Concentrations Of Xylene Research Articles

Facile engineering of metal–organic framework derived SnO2@NiO core–shell nanocomposites based gas sensor toward superior VOCs sensing performance

Aiming to achieve high-sensitivity volatile organic compounds (VOCs), it is of great significance to continuously enhance the sensing performance of metal oxide based sensors. Herein, novel NiO nanoplates-decorated on SnO2 nanofibers 1D core–shell structures derived from metal-organic frameworks (MOFs) are fabricated by the facial solvothermal method and heat treatment for VOCs gas sensors. The morphology and composition of 1D core shell SnO2@NiO are regulated by solvothermal time in the range of 0 ∼ 24 h. Based on the unique structure and composition of SnO2@NiO, SnO2@NiO with 4 h solvothermal time (denoted as SnO2@NiO-4) exhibits excellent selectivity, high response (Ra/Rg = 25.6) and low detection limit as well as good response linearity between response and concentration of xylene. Especially, the obtained SnO2@NiO-8 and SnO2@NiO-16 show the high sensitivity to acetone (Ra/Rg = 28.7) and triethylamine (Ra/Rg = 13.7), respectively. Structural characterizations such as SEM, TEM, and Mott-Schottky results demonstrate the core–shell structure with p-n heterojunction. In-depth investigations on reaction mechanism reveal XPS, photoluminescence (PL), and ESR testing reveal the intrinsic defects such of oxygen vacancy and Ni3+ active sites. And in situ FTIR, online mass spectroscopy, as well as UV/UPS analysis further discover the evolution of intermediates and products during the surface catalysis reaction. These results demonstrate that the remarkable sensing performance of SnO2@NiO-8 can be attributed to several factors, including abundant oxygen vacancy, formation of p-n heterostructure and efficient Ni3+/Ni2+ catalyzing, which beneficial for increased active sites and enhanced electron transport. This synthetic strategy provides an effective method for the facile engineering of high-performances metal oxide-based sensors towards practical health assessment.

A novel method for real-time inhalation toxicity assessment in mice using respirometric system: A promising tool for respiratory toxicology

Inhalation toxicity assessment is a crucial tool for the identification and classification of hazardous materials like volatile organic carbons, aerosols, and particulate matter. Unlike traditional acute inhalation toxicity studies that use mortality as an endpoint, the Fixed Concentration Procedure (FCP) emphasizes "evident toxicity" by monitoring behavior, weight, and food intake. This reduces reliance on mortality but doesn't directly address respiratory system impact. The present study introduced a respirometer-based inhalation toxicity and respiratory status assessment method. The toxicity evaluation system integrated a respirometric system with an animal exposure chamber, enabling real-time monitoring of oxygen consumption. The ICR mice were exposed to various concentrations of benzene (10, 20, 40, and 80 mg/L of air), toluene (7.5, 15, 30, and 60 mg/L of air), and xylene (7.5, 15, 30, and 60 mg/L of air). The respiration rate decreased by 70 % and 69 % for benzene (80 mg/L of air) and toluene (60 mg/L of air), respectively, with EC50 values of 32.5 mg/l and 21.2 mg/L based on oxygen consumption. Xylene did not exhibit EC50 values at the tested concentrations. However, the oxygen consumption rate significantly decreased (46 %) at high concentrations (60 mg/L of air), indicating sub-lethal toxicological effects. Furthermore, the present study was also validated in the bleomycin-induced idiopathic pulmonary fibrosis (IPF) model, demonstrating its reliability as a respiratory impairment marker. The results exhibited a strong correlation between weight loss and less oxygen consumption in the BLM group (bleomycin-induced) as compared to the SHAM group (control), which was confirmed by histological examination and protein marker analysis. The results suggest the potential use of oxygen consumption as an endpoint measurement in inhalation toxicity assessment tests without animal sacrifice, and the present study could be useful for providing valuable insights into disease progression and pharmacological interventions.

Mediating effect of oxidative stress on blood pressure elevation in workers exposed to low concentrations of benzene, toluene, and xylene (BTX).

To investigate the mediating effect of oxidative stress on the relationships between low-concentration benzene, toluene, and xylene (BTX) exposure and blood pressure in workers. A cross-sectional study involving 841 workers from a petroleum refining enterprise in Hainan, China, was conducted. Among the workers, 615 workers were exposed to low-concentration BTX, and 216 workers were in the control group. S-phenylmercapturic acid (S-PMA), hippuric acid (HA), and methyl hippuric acid (MHA, including the three isomers 2-MHA, 3-MHA, and 4-MHA) were measured in the urine of workers via high-performance liquid chromatography‒tandem triple quadrupole mass spectrometry to assess the internal BTX burden. Oxidative stress markers, blood pressure, and their correlations were analysed in both the exposed and control groups of workers. Mediation analysis was used to investigate the potential role of oxidative stress in the relationship between BTX exposure and blood pressure. The concentrations of BTX at the sampling points in the enterprise were all below the limits stipulated in China's national occupational health criteria: occupational exposure limits for hazardous agents. With respect to the internal burden of BTX, the concentrations of the benzene metabolite S-PMA, the toluene metabolite HA, and the xylene metabolites 3-MHA and 4-MHA in the urine samples in the exposure group were greater than those in the control group (P < 0.05). The correlation analysis results revealed that the concentration of the benzene metabolite S-PMA in workers' urine was positively correlated with diastolic blood pressure (DBP) (r = 0.265, P < 0.05). Compared with those in the control group, DBP was greater (β = 1.363, 95% CI 0.088 -2.639), serum superoxide dismutase (SOD) activity was lower (β = - 0.037, 95% CI - 0.060 to - 0.013), and the serum malondialdehyde (MDA) concentration was greater (β = 0.066, 95% CI 0.022-0.110) in the exposure group. Partial correlation analysis revealed a positive correlation between DBP and MDA (rs = 0.115, P < 0.01). The results of the mediation analysis indicated that MDA was a complete mediator between low BTX exposure and DBP (P < 0.05). Occupational exposure to low concentrations of BTX elevates blood pressure and oxidative stress among workers. A positive correlation between DBP and MDA was observed, with MDA acting as a complete mediator between low-concentration BTX exposure and DBP elevation.

How to use efficiently airborne criteria pollutants and radon-222 in source apportionment: A self-organizing maps approach

Pollutant source apportionment represents one of the fundamental activities in environmental science. Several efficient chemometric tools are available to the scope, mostly based on multivariate techniques and usually applied to aerosol chemical speciation data. In the present work, an alternative source profiling method is proposed, based on the self-organizing maps (SOM) algorithm. Moreover, the dataset used includes typical criteria pollutants and physical parameters related to airborne particulate matter widely used as a complement of aerosol source apportionment and largely available at a higher time resolution than bulk aerosol samplings, allowing the information on the dynamic behavior of the local airshed to be extended. In this work, data was collected at a coastal location in NW Italy, between January and July 2012. Hourly concentrations of typical gaseous pollutants (SO2, NO, NO2, benzene, toluene, (m-p)-xylene, o-xylene), black-carbon and particle number concentrations by an optical particle sizer (OPS) were collected. The dataset was integrated with radon-222 activity concentration and meteorological parameters to enrich and refine the information obtained by SOM computation as well as to improve the air pollution source localization. Despite the lower specificity of criteria pollutants, the approach developed was capable of revealing distinct pollution sources such as the urban background traffic, the coal-fired power plant active at the time of the study, and the harbor, in agreement with previous PM-based source apportionment studies carried out locally, while enlightening peculiar dynamical conditions detectable at the sub-daily time scale. The application of the SOM algorithm, with the integration of meteorological parameters and atmospheric radon, proved to be very efficient in unveiling the air pollution sources.

Enhanced organic aerosol formation induced by inorganic aerosol formed in laboratory photochemical experiments

Atmospheric inorganic gases such as NOx, SO2, and NH3 have diverse effects on the formation of secondary organic aerosol (SOA). A comprehensive investigation is necessary to fully understand the atmospheric processing of SOA. In this study, we examined the photooxidation of xylene isomers in the presence of inorganic gases using a combined facility comprising a smog chamber (SC) and an oxidation flow reactor (OFR). SC experiments at higher xylene concentrations and humid conditions revealed SOA yields of 37%, 39%, and 39% with NH3, compared to 15%, 11%, and 13% without NH3, for o-, m-, and p-xylene, respectively. This increase was primarily attributed to the enhanced formation of secondary inorganic aerosol (SIA) in the presence of NH3, consequently increasing aerosol surface area and aerosol water content (AWC). Vapor wall losses (VWL), estimated using a kinetic method, were substantial even with the elevated aerosol surface area provided by SIA. Additional photochemical reactions in the OFR showed a gradual increase in SOA mass and yield over an atmospheric equivalent aging time of 0.5–4.0 days. In the OFR, the SOA yield increased significantly when negligible xylene remained after SC reactions. Fresh SOA formation in the OFR might have decreased the oxygen-to-carbon ratio and oxidation state of carbon, which gradually increased with increasing OFR aging. High OH radical exposure in the OFR likely caused the photodegradation of SC-formed ON, as evidenced by an abrupt decrease in the NO+/NO2+ ratio measured. This study indicates that SOA formation potential of the aromatic hydrocarbon is highly underestimated without considering the combined effects of inorganic gases along with aging.

Fabrication of surface functionalized QCM sensor for BTX detection at ambient conditions

Developing optimized gas sensors for detecting low concentrations of Benzene, Toluene, and Xylene (BTX) in ambient conditions is advantageous for health and environment monitoring applications. This study reports on the feasibility of using Quartz Crystals Microbalance (QCM) coated by Tungsten Oxide (WO3) to detect BTX compounds. A WO3 layer was deposited on the QCM surface using DC magnetron sputtering. Optical Profilometry (OP), Scanning Electron Microscopy (SEM), and X-ray Diffraction (XRD) were employed to analyze sensor surface morphology and structure. Adsorption properties were studied through the Langmuir adsorption isotherm. Thermal stability was evaluated by thermogravimetric analysis. The response to BTX vapours was investigated using a laboratory-designed gas-sensing setup in ambient conditions. The optimized film thickness was 200.81 ± 0.39 nm for 540 s of sputtering. XRD pattern confirms the amorphous nature, and SEM images of WO3 show the granular microstructure with 200 nm diameter. The developed sensor shows the highest sensitivity for xylene (5.10 ± 0.08 Hz/ppm), followed by toluene (5.69 ± 0.22 Hz/ppm) and benzene (3.36 ± 0.24 Hz/ppm). The limit of detection for BTX was 1.48 ppm, 0.79 ppm, and 0.33 ppm, respectively. The sensor exhibited faster response times of 30 s, 32 s, and 43 s for BTX, respectively. Repeatability of 99 % and reproducibility of 98 % were observed for BTX vapours. The fabricated WO3-coated QCM sensor can detect BTX vapour at room temperature with high sensitivity and response time. Thus, it can play a significant role in detecting BTX in the workplace for health and environment monitoring systems.

Analysis of pollution status and influencing factors of polybrominated diphenyl ethers in household dust in five cities in northern China

Objective: To investigate the pollution levels and influencing factors of polybrominated diphenyl ethers (PBDEs) in household dust in five cities in northern China. Methods: Based on the "Chinese Indoor Environment and Health Surveillance" project carried out by the National Institute of Environmental Health, Chinese Center for Disease Control and Prevention in 2018-2019, during the warm season (April 2018 to September 2018) and the cold season (November 2018 to March 2019), Lanzhou in Northwest China, Shijiazhuang in North China, Panjin in Northeast China, Luoyang in Central China, and Qingdao in East China were selected as the research sites. A total of 87 families were recruited to study residences in real-life scenarios. At the same time, dust samples were collected to detect the concentration of PBDEs. The level of household environmental indicators was measured, and the residential building characteristics and family behavior habits were collected through questionnaires. A total of 142 valid dust samples and 140 valid questionnaires were obtained. The differences in PBDE concentrations across seasons, wind zones, residential building characteristics, and family habits were analyzed. The exploratory factor analysis was performed to investigate the possible sources of PBDEs, and multivariate linear regression was used to explore the factors influencing PBDEs in household dust. Results: The M (Q1, Q3) of total PBDE concentrations in 142 household dust samples in five cities was 144.51 (106.61, 222.65) ng/g in the warm season and 145.10 (98.57, 180.65) ng/g in the cold season, respectively. There were seasonal differences in the concentration of ∑12PBDEs in Luoyang and Shijiazhuang (P<0.01). The concentration of BDE-71 was highest among PBDE homologues, followed by BDE-66 and BDE-47. Three factors were extracted by exploratory factor analysis in the warm season, and the cumulative variance contribution rate was 67.90%. The multivariate linear regression showed that the house completion less than ten years [β (95%CI): 0.186 (0.013, 0.359)], infrequent home cooking [β (95%CI):-0.342 (-0.570, -0.114)], and increased residential PM10 concentration [β (95%CI): 0.001 (0.000, 0.002)] during the warm season, as well as the house far from driveway [β (95%CI): 0.093 (0.013, 0.172)], house area less than 90 m2 [β (95%CI):-0.138 (-0.264, -0.013)], and lower residential xylene concentration [β (95%CI):-0.006 (-0.011, -0.001)] during the cold season might be related to the elevated concentrations of ∑12PBDEs in household dust. Conclusion: The pollution of PBDEs in household dust in five northern cities is at a medium to high level. Years of house completion, frequency of cooking at home, residential PM10 concentration, distance from house to driveway, house area, and residential xylene concentration may influence household PBDE concentrations.

An example of a wastewater treatment project for high concentrations of benzene, xylene, acetophenone, and DOPO generated in the production of phosphorus flame retardant

ABSTRACT Wastewater generated in the production of phosphorus flame retardants contains benzene, xylene, acetophenone, and 9, 10-dihydro-9-oxa-10-phosphoxanthine-10-oxide (DOPO) with larger benzene rings, which are more difficult to biodegrade directly. In this study, the wastewater generated in the production of phosphorus flame retardants applied for high-temperature nylon and reactive phosphorus flame retardant was first treated by the combined process of lime emulsion–flocculation reaction and precipitation–ozone oxidation reaction for degradation of benzene, xylene, acetophenone, and DOPO, and then processed by the secondary combined process of upflow anaerobic sludge bed anaerobic digestion–air flotation–membrane bioreactor bio-contact oxidation; thus, the final concentration of pollutants in the wastewater can reach the relevant limit either for external discharge or as the supplemental water for other production devices. In addition, the detailed chemical degradation mechanisms and removal effects of benzene, xylene, acetophenone, and DOPO in an ozone reactor were explored. After the project had been normally operated for half a year, the test results of the effluent were as follows: chemical oxygen demand, 50 mg/L; BOD5, 20 mg/L; NH3-N, 5.0 mg/L; total phosphorus, 0.5 mg/L; benzene ≤ 0.1 mg/L; xylene ≤ 0.4 mg/L; acetophenone ≤ 0.4 mg/L; and DOPO ≤ 0.02 mg/L. Ultimately, the cost was 2.1 $/m3. It provides a useful process for wastewater treatment related to phosphorus flame retardants.

First exploratory study of gaseous pollutants (NO2, SO2, O3, VOCs and carbonyls) in the Luanda metropolitan area by passive monitoring

An air quality monitoring campaign for gaseous pollutants using passive sampling techniques was carried out, for the first time, at 25 locations in the metropolitan area of Luanda, Angola, in June 2023. Concentrations of benzene, toluene, ethylbenzene, xylenes, trimethylbenzenes, SO2 and NO2 were generally higher in locations more impacted by traffic. Benzene, SO2 and NO2 levels did not exceed the World Health Organisation guidelines. Ozone concentrations surpassed those documented for other African regions. Higher O3 formation potential values were recorded at heavy-trafficked roads. The top 5 species with potential for ozone formation were m,p-xylene, toluene, formaldehyde, propionaldehyde and butyraldehyde. The Mulenvos landfill presented a distinctive behaviour with a very low toluene/benzene ratio (0.47), while values close to 5 were obtained at traffic sites. The maximum levels of α-pinene, D-limonene, formaldehyde, acetaldehyde, acetone, acrolein, propionaldehyde, butyraldehyde, benzaldehyde, valeraldehyde, hexaldehyde and crotonaldehyde were recorded at the landfill. The formaldehyde/acetaldehyde ratio ranged from 0.40 at the Mulenvos landfill to 3.0, averaging 1.8, which is a typical value for urban atmospheres. Acetaldehyde/propionaldehyde ratios around 0.4–0.6 were found in locations heavily impacted by traffic, whereas values between 0.7 and 1.2 were observed in green residential areas and in places with more rural characteristics. All hazard quotient (HQ) values were in the range from 1 to 10, indicating moderate risk of developing non-cancer diseases. The exception was the Mulenvos landfill for which a HQ of 11 was obtained (high risk). The cancer risks exceeded the tolerable level of 1 × 10−4, with special concern for the landfill and sites most impacted by traffic. A mean lifetime cancer risk of 9 × 10−4 was obtained. The cancer risk was mainly due to naphthalene, which accounted, on average, for 94.6% of the total.

Catalytic pyrolysis of wheat straw based on dual catalyst CaO/ZSM-5 with acid washing and torrefaction pretreatment to enhance aromatic yield in bio-oils

In this paper, the catalytic pyrolysis integrating combined pretreatment (acid washing and torrefaction) and dual catalysts was adopted to improve the quality of bio-oil and the selectivity of aromatic hydrocarbons. Combined pretreatment is a highly effective method to improve the quality of biomass feedstock. It was capable of the removal of alkali and alkaline earth metals from wheat straw, with a K removal rate of 97.79 %. Under the combined pretreatment, the aromatic hydrocarbon content in bio-oil increased to 68.8 % using the ZSM-5 catalyst alone. Compared with ZSM-5, CaO could remove part of the oxygenated functional groups and had a better acid removal effect, but the aromatic hydrocarbon yield was low to 7.95 %. After combined pretreatment using simulated aqueous phase bio-oil for acid washing, catalytic pyrolysis using CaO/ZSM-5 dual catalysts greatly enhanced the quality of the bio-oil. The oxygenated compounds content was reduced to 17.58 %, and the total hydrocarbon yield was increased to 82.42 %, especially the aromatic hydrocarbons yield was increased to 79.91 %, of which the monocyclic aromatic hydrocarbons were as high as 68.38 %, and the benzene, toluene, and xylene content reaching 49.39 %. Thus, integrating dual catalysts (CaO/ZSM-5) with combined pretreatment can effectively increase the aromatic yield for producing high-quality bio-oil.

Sensitive analysis of some detrimental volatile organic compounds in fabric, carpet and air freshener using solid phase extraction and gas chromatography–mass spectrometry

Benzene, toluene, ethylbenzene and xylene are known to be lethal environmental contaminants that have carcinogenic and mutagenic influences in human being while styrene and benzaldehyde have a neurotoxic effect. In other hand, the constituents of air freshener considered as a probable source of volatile organic compound. In the present work, a solid phase extraction and gas chromatography–mass spectrometry (GC-MS) technique has been optimized and applied to the fabric, carpet and air freshener samples to determine the trace amounts of benzene, toluene, ethylbenzene, xylene, styrene and benzaldehyde. The SupelcleanTM ENVITM - 18 cartridge with dichloromethane extracting solvent were found to be the optimal procedures. The system presented excellent performance in terms of limit of detection (0.08-0.61 ng/mL), coefficient of determination (0.994-0.997), precision with the relative standard deviation values ranging from 0.05-2.57%. According to the results, the concentration of benzene, toluene, ethylbenzene, xylene, styrene and benzaldehyde in fresheners’ samples was found in the range 0.03-53.27, 0.03-7.12, 0.02-6.51, 0.05-96.44, 0.04-7.06 and 0.22-23.02, respectively. The excellent recovery values were also obtained up to 99.93%. The SupelcleanTM ENVITM - 18 GC-MS system was found to appropriate for the monitoring of analytes in fabric, carpet, air freshener samples, and other samples of the similar constituents. KEY WORDS: BTEX, Styrene, Benzaldehyde, Air freshener, Solid phase extraction, Gas chromatography–mass spectrometry Bull. Chem. Soc. Ethiop. 2024, 38(6), 1543-1556. DOI: https://dx.doi.org/10.4314/bcse.v38i6.4

Relationship Between Xylene, Rq Xylene Concentration and Enzyme Activity as Indicators of Heart and Liver Function Among Shoe Industry Workers In Surabaya

Background Xylene, a common solvent in painting, printing, and shoemaking, enters the body through inhalation of vapors. Methods This observational analytic study aimed to examine the relationship between xylene concentration, xylene RQ, and liver function in industrial workers in Surabaya, especially in shoe industries. The chi-square method was utilized for data analysis. To ensure the validity and reliability of the study results, air and blood sampling procedures were implemented. Air sampling was conducted to measure xylene concentrations in the workplace environment, while blood samples were collected from workers to assess Serum Glutamic Oxaloacetic Transaminase (SGOT) and Serum Glutamic Pyruvate Transaminase (SGPT) levels. The study was conducted in five regions in Surabaya, namely Kalijudan, Ketintang, Jemursari, AUP, and Romokalisari. The population includes a total of 90 workers with 77 of them taken as samples using the accidental sampling method. Results The results show that there is a relationship between xylene concentration and Serum Glutamic Oxaloacetic Transaminase (SGOT) levels (p&gt; 0.05); (r = 0,65) and there is no relationship between xylene concentrations and Serum Glutamic Pyruvate Transaminase (SGPT) levels (p&gt; 0.05); (r = -0,12). There was no relationship between RQ and SGOT levels (p&gt; 0.05) and there was no relationship between RQ and SGPT levels (p&gt; 0.05). However, from the calculation of the prevalence ratio, workers with unsafe RQ (RQ&gt;1) have a 7.09x greater chance of experiencing damage to SGOT levels and a 1.06x greater chance of experiencing damage to SGPT levels. Conclusions Xylene exposure (concentration &amp; RQ) affects liver enzyme levels (SGOT/SGPT) in workers. Industries should consider providing nutritious food to aid xylene removal and stricter safety policies are needed. This study highlights the importance of a holistic approach to worker health and safety when dealing with hazardous chemicals.

BTEX concentration and health risk assessment in automobile workshops

This study focused on the measurement of BTEX (benzene, toluene, ethylbenzene, and xylene) concentrations in the air of indoor and outdoor environments of automobile workshops in Damghan, Iran. Air samples from twenty-five workshops were actively collected and analyzed using Gas Chromatography-Flame Ionization Detection (GC-FID). The results showed that the concentrations of BTEX were higher in the indoor air compared to the outdoor air. The highest mean concentration of benzene (153.22 ± 34.21 μg m−3), toluene (94.41 ± 25.25 μg m−3), and xylenes (385.38 ± 34.21 μg m−3) was found in auto paint (AP) workshops, while the highest mean concentration of ethylbenzene (43.39 ± 12.57 μg m−3) was observed in auto body (AB) workshops. The significant negative correlations between benzene, ethylbenzene, xylene isomers, and relative humidity (RH) indicated that controlling humidity is an effective strategy. The mean inhalation lifetime cancer risk (LTCR) for benzene in both indoor and outdoor air of all automobile workshops exceeded the EPA (Environmental Protection Agency) recommended limits. The highest mean LTCR values for benzene and ethylbenzene were observed in the AP (3.24E10-4) and AB (2.95E10-5) workshops, respectively. The hazard quotient (HQ) of benzene and Xylene in the indoor air of the AP and AB workshops was >1, which indicates that the non-carcinogenic risks associated with exposure to these compounds are considerable. This study underscores the need for international attention to BTEX pollution in automobile workshops, highlighting the global health risks. The findings provide crucial data for developing strategies to mitigate these risks and protect workers’ health.

Study of the Chemical Recovery and Selectivity against U in the Radiochemical Separation of Th with Tri-n-butyl Phosphate by Varying the Proportion of Xylene and HCl Concentration.

Thorium is a radionuclide used in various environmental studies such as dating, sediment movement, soil-plant transfer studies, and contamination of waste from the natural fuel cycle. The liquid-liquid extraction method using tri-n-butyl phosphate (TBP) allows for the separation of Th from the accompanying actinides. However, the separation of Th and U present in the same sample is not trivial. This separation is influenced by the starting acid (HCl or HNO3), the concentration of TBP in an organic solvent, and the concentration of the acid used for re-extracting Th, which is typically HCl. Therefore, it is necessary to study these factors to ensure that the method has sufficient chemical yield and selectivity in complex matrices. This study presents a systematic investigation of the aforementioned parameters, making the necessary variations to select an optimal method for the radiochemical separation of Th. The ideal conditions were obtained using 4 M HCl as the acid prior to extraction, a 1:4 solution of TBP in xylene, and 4 M HCl as the re-extracting agent. The accuracy and precision were studied in four intercomparison exercises conducted in quadruplicate, using the parameters Enumbers, RB(%), and RSD(%) for 232Th and 230Th. The sensitivity of the method was experimentally studied and the limit of detection (LoD) was determined according to ISO 11929:2005. Additionally, the linearity of the method showed that the experimental and theoretical activity concentrations of 232Th and 230Th had slopes of 1 with an intercept close to 0.

Impact of polymer structure in polyurethane topcoats on anti-icing properties

Icing on the topcoat layer of structures or mobility systems can be a factor leading to functional failures or accidents. Material engineering approach to prevent icing involves creating hydrophobic surfaces. In this study, it was confirmed that the method of controlling the structure of polymers using solvents to adjust surface hydrophobicity and ice prevention effects is effective. Polyurethane (PU) topcoats are primarily used on the exterior of mobility devices; therefore, structure of PU was manipulated using xylene. Through the adjustment of the ratio between PU and xylene, changes in the curing enthalpy and crystal structure were observed, which led to alterations in tensile strength. Additionally, changes in surface energy and contact angle occurred depends on xylene content, and de-icing property of PU topcoat was enhanced by 66 % on the surface of the 20 vol% xylene PU topcoat, compared to the pure PU topcoat. It was confirmed that the basic method of manipulating the polymer structure through solvent amount in topcoats could be utilized as a technique in hydrophobic surface research, such as ice prevention.

Investigation of BTX Concentrations and Effects of Meteorological Parameters in the Steelpoort Area of Limpopo Province, South Africa

It has been demonstrated that benzene, toluene, and xylene are carcinogens. Its combined effects with other contaminants have the potential to harm several ecosystem components. Since most human benzene exposure takes place inside, it is important to understand how outdoor benzene emissions from traffic and industry affect interior concentrations. However, this area of study has not received enough attention to date. Herein, we examine the outdoor concentrations of benzene, toluene, and xylene (BTX) in a Steelpoort mining area. BTX pollutants were passively sampled on the first seven days of the month, from January to December 2021 using Radiello samplers. The effects of meteorological parameters such as temperature, relative humidity, wind speed, and solar radiation on BTX concentrations were also statistically tested. For all seasons, BTX concentrations were greater in the winter than in the summer with concentrations of 0.69 µg/m3, 2.97 µg/m3 and 0.80 µg/m3 for benzene, toluene and xylene, respectively. In addition, toluene was the most common BTX compound with the highest concentrations when compared to benzene and xylene. Benzene, toluene and xylene, had yearly average concentrations of 0.61 µg/m3, 1.48 µg/m3 and 0.64 µg/m3, respectively. The benzene and xylene concentrations were below international exposure limits (annual, 5 µg/m3 for benzene; weekly, 260 µg/m3 for toluene), as in comparison to the World Health Organization, as well as within South African exceedance limits. Both positive and negative correlations between BTX and meteorological parameters were demonstrated by statistical models. Temperature, wind speed, and relative humidity depicted a weak negative correlation with benzene of 0.003, 0.019 and 0.006, respectively. Toluene showed a positive correlation with wind speed (1.90) and relative humidity (0.041). Overall, the concentration of benzene is of major concern since it is an agent of cancer and it is there in the atmosphere.

Exposure and health risk assessment of volatile organic compounds among drivers and passengers in long-distance buses

Exposure to volatile organic compounds (VOCs) such as benzene, toluene, ethylbenzene, xylene, and formaldehyde from long-distance buses has been reported to adversely affect human health. This study investigates the concentrations of these five VOCs and evaluates their health risks to drivers and passengers on board. Ten trips from Taipei to Taichung were performed during the warm and cold seasons of 2021–2022. Two locations inside the bus were established to collect air samples by a 6-liter canister for drivers and passengers. Exposure concentrations of benzene, toluene, ethylbenzene, and xylene were analyzed via gas chromatography with a flame ionization detector and the formaldehyde concentration was monitored using a formaldehyde meter. Subsequently, a Monte Carlo simulation was conducted to evaluate the carcinogenic and non-carcinogenic risks of the five VOCs. Formaldehyde emerged as the highest detected compound (9.06 ± 3.77 μg/m3), followed by toluene (median: 6.11 μg/m3; range: 3.86–14.69 μg/m3). In particular, formaldehyde was identified to have the significantly higher concentration during non-rush hours (10.67 ± 3.21 μg/m3) than that during rush hours (7.45 ± 3.41 μg/m3) and during the warm season (10.71 ± 2.97 μg/m3) compared with that during the cold season (7.41 ± 4.26 μg/m3). Regarding non-carcinogenic risks to drivers and passengers, the chronic hazard indices for these five VOCs were under 1 to indicate an acceptable risk. In terms of carcinogenic risk, the median risks of benzene and formaldehyde for drivers were 2.88 × 10−6 (95% confidence interval [CI]: 2.11 × 10−6 – 5.13 × 10−6) and 1.91 × 10−6 (95% CI: 4.54 × 10−7 – 3.44 × 10−6), respectively. In contrast, the median carcinogenic risks of benzene and formaldehyde for passengers were less than 1 × 10−6 to present an acceptable risk. This study suggests that benzene and formaldehyde may present carcinogenic risks for drivers. Moreover, the non-carcinogenic risk for drivers and passengers is deemed acceptable. We recommended that the ventilation frequency be increased to mitigate exposure to VOCs in long-distance buses.

Study on the effect of residential interior decoration on children’s respiratory diseases: A field trial conducted in Chongqing, China

Pollutants such as formaldehyde, benzene series compounds and total volatile organic compounds (TVOC) released by residential interior decoration activities (including household renovation and new furniture) pose a severe threat to children’s respiratory health. To study the effect of indoor decoration on children’s respiratory diseases and provide suggestions to prevent it, we conducted a cross-sectional questionnaire survey amongst 6547 preschoolers from 34 kindergartens in Chongqing, China, and selected 39 houses to measure their indoor air pollutants concentrations. The results showed that household decoration, during pregnancy and early childhood, would increase the risk of children’s rhinitis, asthma and pneumonia. Vacancy time after the completion of decoration, furniture pieces and decoration materials significantly affected the concentration of formaldehyde, xylene and TVOC, which could pose a potential risk to children’s respiratory health. The concentration of xylene and TVOC and the incidence of children’s asthma and pneumonia were both negatively correlated with the vacancy time. Decoration materials such as composite and ceramic tile/stone/cement flooring and water-based/latex/oil-based paints emit more gaseous pollutants than solid wood flooring and wallpaper, respectively, which were more likely to increase the risk of children’s respiratory diseases. Adequate ventilation and air purification can reduce the impact of home decoration.

Assessment of genotoxicity in Clarias gariepinus exposed to lethal and sub-lethal concentrations of oilfield chemicals: DNA concentration, purity, and genetic implications

This study investigates the concentration and purity of DNA extracted from Clarias gariepinus after exposure to lethal concentrations (250 ml/l, 200 ml/l, 150 ml/l, 100 ml/l, 50 ml/l, 25 ml/l and 0.0 ml/l for the control) of Xylene: Diesel (X:D) and Oilfield-Based Emulsifiers (O-BE) over 96 hours using static bioassays and sub-lethal concentrations 0 ml/l (control), 12.8 ml/l, 25.6 ml/l, 38.4 ml/l, 51.2 ml/l and 64.0 ml/l) using renewal bioassay for 28 days. 210 juveniles were used for the experiment. The study used PCR and other methods to analyse DNA concentrations and purity in the fish samples. The results indicated variations in DNA concentration, purity, and the presence of micronuclei, suggesting genetic and cytogenetic responses to chemical exposures. The highest DNA concentration was recorded in the 25 ml/l group for both O-BE and X:D, while the lowest was in the 100 ml/l group. The genetic effects of Xylene: Diesel on the molecular level were also examined, with significant gaps in the alignments of experimental groups indicating notable differences in the sequences compared to the control group without chemical exposure. Through detailed analyses, including gel electrophoresis and sequence alignment, the study explores genetic variations and micronuclei frequencies in blood cells, shedding light on the ecotoxicological impacts and potential evolutionary implications of these oil-based substances on African catfish. Understanding the genetic variations induced by lethal concentrations of O-BE in Clarias gariepinus is crucial for assessing the broader environmental impact, as genetic changes in aquatic organisms can affect population health, adaptation, and ecosystem dynamics.

Branched ZnFe2O4 nanorods grown via chemical spray pyrolysis technique for chemiresistive xylene gas sensor

In this work, we used a chemical spray pyrolysis technique to deposit zinc ferrite (ZF) thin films at different substrate temperatures to study xylene (C8H10) gas sensing properties. The focus is on the detection of xylene, a volatile organic compound (VOC) that is harmful to human health. It was found that the concentration of hazardous xylene gas was below the exposure limit. The substrate temperature has a notable impact on the sensor's performance, and ZF exhibits promise for discerning xylene selectively at 200 °C operating temperature. The results indicate that the ZF film deposited at 225 °C (ZF-B) exhibited a significant response (S = 47.4%) to a 50-ppm xylene concentration. Further analysis illustrates that the film substrate temperature deposited at 225 °C can have a unique morphology including thin branched rods, small nanorods with high surface area and roughness. These features contribute to enhanced sensing response by creating more active centers for gas molecule interactions. The stability test over 125 days indicates that the ZF-B film acts effectively as a xylene gas sensor, emphasizing the effectiveness of ZF thin films in detecting xylene in an air environment.