Styrene Concentration Research Articles

A comparative study of photocatalytic degradation of airborne styrene using TiO2 and ZnO nanoparticles immobilized on activated carbon

Background: With the growth of industries and advancing civilization, controlling air pollution from both human and natural sources has become a major concern. Styrene, a volatile organic compound (VOC), is recognized as a hazardous and toxic atmospheric contaminant. Methods: In this study, the removal of Styrene vapors using ZnO and TiO2 nanoparticles coated on activated carbon (AC) was investigated and the styrene removal capacity of AC-ZnO and AC-TiO2 catalysts was compared. The coated adsorbents were characterized using a field emission scanning electron microscope (FESEM), X-ray diffraction patterns (XRD), and the Brunauer–Emmett–Teller (BET) method. All laboratory-scale experiments were conducted at ambient temperatures. Styrene concentrations of 50, 100, and 300 ppm were tested at an input flow rate of 0.03, and 0.06 m3 /h. Results: The AC-TiO2 catalyst had a styrene removal efficiency (RE) of 81%, as compared to 74% efficiency for the AC-ZnO catalyst, this is at a flow rate of 0.06 m3 /h and a concentration of 50 ppm. The results indicated that increasing styrene concentrations reduced breakthrough time but increased adsorption capacity. Also, by increasing the inflow rate, the adsorption capacity decreased. At all concentrations and flow rates, the adsorption capacity of the AC-TiO2 catalyst was higher than the AC-ZnO catalyst. Conclusion: According to the results, it can be concluded that the AC-TiO2 catalyst is more effective in the removal of Styrene vapor from the air as compared to the AC-ZnO catalyst.

Effect of Styrene Concentration on Tensile Properties of Styrene-Acrylate Films

Abstract Due to an increasing awareness of environmental protection, waterborne coatings have replaced solvent-borne ones. The waterborne styrene-acrylate dispersion was successfully synthesized using emulsion polymerization. In this work, the emulsion was composed of Butyl Acrylate (BA) and Styrene (Sty) at different ratios. FTIR spectra confirmed the successful copolymerization of BA and Sty. Additionally, it was observed that all emulsions exhibited a consistent hydrodynamic diameter (120 nm to 140 nm), polydispersity index (between 0.030 and 0.050), and zeta potential (-40 mV to -60 mV). Thus, the BA/St ratio did not impact particle growth during emulsion polymerization. Furthermore, an increase in Sty concentration raised the glass transition temperature (Tg) of the films from 10.8 °C to 30.8 °C. This is attributed to Sty being a high Tg polymer, contributing to a rigid monomer that could enhance rigidity and restrict the movement of polymer chains. Additionally, the tensile strength of the dispersion films increased with the increase in Sty concentration, from 3.01 MPa to 5.88 MPa. Interestingly, the elongation at break did not significantly change as the St concentration increased, dropping by 15%. The investigation to aid in establishing relationships between the monomer concentration and mechanical properties of styrene-acrylate films.

Assessment of the Workers' Exposure to Styrene in a Polymer Manufacturing Industry: Correlation Between Air and Biological Monitoring Methods

Background and Objective: Styrene is widely used in the production of many products, such as paints, glues, and plastics. There is a high potential for exposure to this toxic solvent in workplaces. The present study aimed to assess the levels of exposure to styrene via air and biological monitoring methods and determine the correlation between them in styrene-exposed workers. Materials and Methods: A total of 44 workers from a polymer manufacturing industry were studied, and the workers’ inhalational exposure to styrene was measured. In addition, the levels of urinary mandelic acid were determined. Data was analyzed using the SPSS (version 22.0) software. Results: The time-weighted average (TWA) exposure to styrene was equal to 18.35±11.02 ppm. The mean urinary mandelic acid was 150 mg/g creatinine. Moreover, a significant correlation was observed between the styrene concentration and the urinary mandelic acid (r=0.841). The correlation was stronger in workers with no skin exposure than in those with this type of exposure. Furthermore, a significant correlation was observed based on working hours per day (less than or more than 8 hours per day) so that the correlation was better for workers with shorter exposures (r= 0.922 vs. 0.713). Conclusion: The findings of the present study indicated a relatively strong correlation between inhalational exposure to styrene and the levels of mandelic acid in urine. In addition, smoking and working conditions, such as skin exposure and working hours per day, can affect the levels of urinary mandelic acid. Therefore, these factors should be considered in the exposure assessment of workers exposed to styrene.

Ethylene/Styrene Copolymerization by (Me3SiC5H4)TiCl2(O-2,6-iPr2-4-RC6H2) (R = H, SiEt3)-MAO Catalysts: Effect of SiMe3 Group on Cp for Efficient Styrene Incorporation.

The synthesis and structural analysis of (Me3SiC5H4)TiCl2(OAr) [OAr = O-2,6-iPr2-4-RC6H2; R = H, SiEt3] revealed that it exhibits higher catalytic activities than (tBuC5H4)TiCl2(OAr), Cp*TiCl2(OAr), with efficient comonomer incorporation in ethylene/styrene copolymerization in the presence of a methylaluminoxane (MAO) cocatalyst. The catalytic activity in the copolymerization increased upon increasing the charged styrene concentration along with the increase in the styrene content in the copolymers, whereas the activities of other catalysts showed the opposite trend. (Me3SiC5H4)TiCl2(O-2,6-iPr2C6H3) displayed the most suitable catalyst performance in terms of its activity and styrene incorporation, affording amorphous copolymers with styrene contents higher than 50 mol% (up to 63.6 mol%) and with random styrene incorporation confirmed by 13C-NMR spectra.

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

Evaluation of Grafting Parameters of Styrene onto Alkaline Modified Sugarcane Bagasse using Fe2+/H2O2 and Fe2+/H2O2-N2H4 initiator systems and Characterization of the Hydrolyzed Grafted Polystyrene Chains

Cellulose the most abundant natural fibre can be modified, via grafting with vinyl monomers, in homogenous or heterogeneous reaction medium. Therefore, the objective of this paper was to study the grafting parameters of styrene onto alkaline modified sugarcane bagasse using Fe2+/H2O2 and Fe2+/H2O2- N2H4 initiator systems and characterized the hydrolyzed grafted polystyrene chains for their viscometry and average molecular weight distributions using standard appropriate methods. The grafting parameters increases within 0.10-0.25 M styrene concentration in both initiator systems and initiator concentration within the range 1.0x10-3 to 6.0x10-3 for Fe2+/H2O2- N2H4 and 1.0x10-3 to 9.0x10-3 for Fe2+/H2O2 systems, albeit with higher values in the former system. These parameters decrease at higher monomer and initiator concentrations in both systems. The viscometry of hydrolyzed polystyrene chain prepared at optimum initiator concentrations and 0.10-0.30 M styrene concentration in both initiator systems are in the range (1.6416-4.5327 cP), (0.6416-3.5327 cP) and (73.2277-202.1927 cP) for relative, specific and inherent viscosities respectively, consistent with increases in activation energy of flow (1.24-5.30 KJmol-1) and average viscosity molecular weights (307.92-565.79 gmol-1) , these parameters decreases at higher monomer concentration in both initiator systems. The number and weight-average molecular weight distributions and polydispersity indices indicates that grafted polystyrene chains in Fe2+/H2O2 system are broader and more polydispersed than those for Fe2+/H2O2- N2H4 initiator system. The results showed that the hydrazine enhanced initiator system was more effective for the copolymerization reaction with polystyrene polydispersity indices comparable to those of synthetic chain-growth polymers.

Competent visible light driven photocatalytic removal of gaseous styrene over TiO2/g-C3N4: Characterization, parameters, kinetics, mechanism

BackgroundRemoval of volatile organic compounds (VOCs), including styrene, via photocatalytic oxidation is preferable. The photocatalytic activity of g-C3N4 and TiO2 are limited by its fast recombination rate and wide band gap, respectively. MethodThis study examined improvement in photocatalytic degradation of styrene using g-C3N4 after doping with various proportions of TiO2. The best photocatalyst were also tested under various conditions (retention time, relative humidity, styrene concentration, and temperature) prior to study of reaction kinetics. Significant findings20 wt% TiO2/g-C3N4 presented the best styrene conversion and supported by characterization result. Formation of narrow band gap reached to 2.68 eV enhanced the performance of doped g-C3N4. Langmuir Hinshelwood model 4 presented a well fitted result with the experimental data.

Biostimulation of styrene-containing wastewater in carrier-supported anaerobic bioreactor towards enhancing biogas production and styrene degradation

Biological treatment of styrene-containing petrochemical wastewater usually suffers from styrene volatility and its toxicity to microorganisms. The main aim of the present study was to enhance the treatment performance of synthetic petrochemical wastewater using carrier-supported anaerobic bioreactor, in terms of biogas production and styrene degradation. For this purpose, three types of carrier, including magnetic granular activated carbon (MGAC), cuttlefish bone (CFB) and pumice, were used. A control reactor and the three carrier-supported reactors were operated under three styrene concentrations of 20 (cycle 1), 50 (cycle 2), and 100 (cycle 3) mg/L. Ethanol was used as a co-solvent and the total chemical oxygen demand (COD) was 500 mg/L in each cycle. According to the results, under all examined styrene concentrations, all the carrier-supported reactors exhibited higher styrene removal efficiency and gas production than the control reactor. Among carrier-containing rectors, the reactor supplemented with MGAC showed the best performance with styrene removal of 85.4 %–91.4 % and gas production of 368–890 mL/g COD added. The corresponding values for the control reactor were 72.3–79.2 % and 174–358 mL/g COD added. In addition, Carrier-containing reactors showed 31.2–67.2 % less styrene volatilization than the control reactor. The process performance was also affected by the styrene concentration so that the highest and the lowest gas productions were achieved for styrene contents of 50 and 100 mg/L, orderly. Using modified Gompertz model, it was found that the carriers shortened the lag phase and increased the maximum methane production rate, proving the establishment of stable conditions in carrier-supported reactors for the treatment of styrene-containing wastewater.

Biologically templated Fe2O3–CuO heterojunction for ppb-level styrene gas detection

The widespread industrial use of styrene highlights the urgent need for detecting and monitoring its harmful gases. The innovation of this study lies in synthesizing uniform Fe2O3 nanoparticles using Ginkgo biloba and calcining them with CuOHF to prepare nanostructured materials, enhancing the performance of gas sensors. The effects of varying α-Fe2O3 additions and calcination temperatures on the structure and gas-sensitive properties of the composites were systematically investigated. The results revealed that the optimal operating temperatures of the CuO–10%Fe2O3-400 sensor were reduced by 80 and 50 °C, and its response to 100 ppm styrene at 200 °C was significantly enhanced by 3.2-fold and 4.2-fold, respectively, compared to the single Fe2O3 and CuOHF sensors. It is particularly noteworthy that the sensor exhibits excellent detection performance at a 50 ppb styrene concentration, with a response value of 1.2. The lamellar structure of CuOHF serves as a precursor for CuO, thereby increasing the surface area of the sensor in contact with the gas. During the calcination process, the released gases contribute to the formation of a porous structure, which together improves the adsorption capacity and stability of the sensor. Additionally, the heterojunction formed by the calcination of CuO (p-type) and Fe2O3 (n-type) enhances charge transfer and increases gas adsorption capacity, highlighting its potential as a gas sensor. This composite material exhibits good sensitivity and reliability in monitoring hazardous gases like styrene, underscoring the significant value of this study in environmental monitoring and safety control.

Influence of dielectric barrier discharge plasma processing in the volatile compounds and aroma of cashew apple juice

Cashew apple juice is a popular beverage in several parts of the world due to its unique fruity aroma. However, the high styrene concentration contributes to an undesirable balsamic note. To address this issue, cold plasma technology was proposed to alter the juice's volatile compounds, thereby improving its flavor. This study has evaluated the effects of cold plasma on the volatile compounds and aroma of cashew apple juice. The research was conducted by applying dielectric barrier discharge plasma to the juice, varying the frequency (50–1000 Hz) and processing times (5–20 min) while keeping a constant voltage (18 kV). The plasma treatment induced noteworthy changes in the volatile compounds of the juice. Specifically, there was a significant decrease in volatile organic acids (73%) and an increase in aldehydes (52%), alcohols (67%), and short-chain esters (11%). Plasma induced the internal scission of fatty acids and esters, which resulted in the formation of short-chain esters and aldehydes. Further processing has oxidized the aldehydes, generating alcohols and isomerized short-chain esters, which generate branched esters. Cold plasma, however, did not significantly reduce the styrene concentration and could not mitigate the off-flavor caused by this compound.

Fus-SMO: Kinetics, Biochemical Characterisation and In Silico Modelling of a Chimeric Styrene Monooxygenase Demonstrating Quantitative Coupling Efficiency.

The styrene monooxygenase, a two-component enzymatic system for styrene epoxidation, was characterised through the study of Fus-SMO - a chimera resulting from the fusion of StyA and StyB using a flexible linker. Notably, it remains debated whether the transfer of FADH2 from StyB to StyA occurs through diffusion, channeling, or a combination of both. Fus-SMO was identified as a trimer with one bound FAD molecule. In silico modelling revealed a well-distanced arrangement (45-50 Å) facilitated by the flexible linker's loopy structure. Pre-steady-state kinetics elucidated the FADox reduction intricacies (kred=110 s-1 for bound FADox), identifying free FADox binding as the rate-determining step. The aerobic oxidation of FADH2 (kox=90 s-1) and subsequent decomposition to FADox and H2O2 demonstrated StyA's protective effect on the bound hydroperoxoflavin (kdec=0.2 s-1) compared to free cofactor (kdec=1.8 s-1). At varied styrene concentrations, kox for FADH2 ranged from 80 to 120 s-1. Studies on NADH consumption vs. styrene epoxidation revealed Fus-SMO's ability to achieve quantitative coupling efficiency in solution, surpassing natural two-component SMOs. The results suggest that Fus-SMO exhibits enhanced FADH2 channelling between subunits. This work contributes to comprehending FADH2 transfer mechanisms in SMO and illustrates how protein fusion can elevate catalytic efficiency for biocatalytic applications.

The Effect of Wooden Building Materials on the Indoor Air Quality of Houses

This work focuses on researching wood as a low-emitting building material. Many studies showed that by regulating the emission of adverse chemicals from pressed wood products, they could be recycled as low-emitting materials. The presented case study, shows the measurements of the indoor air quality in a passive, low-energy, wooden, light frame house. Concentrations of Volatile Organic Compounds (VOC) and formaldehyde were measured and compared with data from other case studies made in this subject and with the current Hungarian and international regulations of adverse chemicals. The main VOC materials which concentrations were significant in all measurements were terpenes (limonene, alpha-pinene, 3-carene), aliphatic-hydrocarbons and aldehydes (acetic acid, 2-Methoxy-1-ethylmethyl acetate). The comparison showed that the concentrations of benzene, toluene, naphthalene, formaldehyde, and styrene were not deviant from the average values measured by other case studies. The observations showed that the main influencing factors of indoor air quality were the changes in indoor temperature, relative humidity, air exchange rate, and human activities. The conclusion is that the wooden materials applied in the house are low-emitting materials and do not pose a health risk for people.

Predictive modeling of coke formation in ethylbenzene cracking on 304 H austenitic steel surface using response surface methodology (RSM)

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.

Sensory Perception and Consumer Acceptance of Carrot Cultivars Are Influenced by Their Metabolic Profiles for Volatile and Non-Volatile Organic Compounds.

Sensory parameters as well as the volatile and non-volatile compound profiles of sixteen carrot cultivars were recorded to obtain insight into consumer preference decisions. The sensory test was carried out with a consumer panel of 88 untrained testers allowing a clear acceptance-based differentiation of the cultivars. Five individual sensory characters (sweetness, overall aroma, bitterness, astringency and off-flavor) supported this discrimination. Chemical analyses of volatile organic compounds, polyacetylenes, phenylpropanoids and sugars enabled us to correlate the influence of these ingredients on sensory perception. Higher concentrations of α-pinene, hexanal, styrene and acetophenone correlated with a better acceptance, as well as sweetness and overall aroma perception. In contrast, a low acceptance as well as a stronger perception of bitterness, astringency and off-flavor correlated with enhanced concentrations of camphene, bornylacetate, borneol, myristicine, falcarindiol, falcarindiol-3-acetate, laserin and epilaserin. The present study should support the development of new breeding strategies for carrot cultivars that better satisfy consumer demands.

Spatiotemporally resolved emissions and concentrations of styrene, benzene, toluene, ethylbenzene, and xylenes (SBTEX) in the US Gulf region

Abstract. Styrene, benzene, toluene, ethylbenzene, and xylenes (SBTEX) are established neurotoxicants. SBTEX contains hazardous air pollutants (HAPs) that are released from the petrochemical industry, combustion process, transport emission, and solvent usage sources. Although several SBTEX toxic assessment studies have been conducted, they have mainly relied on ambient measurements to estimate exposure and limit their scope to specific locations and observational periods. To overcome these spatiotemporal limitations, an air quality modeling system over the US Gulf region was created, predicting the spatially and temporally enhanced SBTEX modeling concentrations from May to September 2012. Due to the incompleteness of SBTEX in the official US Environmental Protection Agency (EPA) National Emission Inventory (NEI), the Hazardous Air Pollutions Imputation (HAPI) program was used to identify and estimate the missing HAP emissions. The improved emission data were processed to generate the chemically speciated hourly gridded emission inputs for the Comprehensive Air Quality Model with Extensions (CAMx) chemical transport model to simulate the SBTEX concentrations over the Gulf modeling region. SBTEX pollutants were modeled using the Reactive Tracer feature in CAMx that accounts for their chemical and physical processes in the atmosphere. The data show that the major SBTEX emissions in this region are contributed by mobile emissions (45 %), wildfire (30 %), and industry (26 %). Most SBTEX emissions are emitted during daytime hours (local time 14:00–17:00), and the emission rate in the model domain is about 20–40 t h−1, which is about 4 times higher than that in the nighttime (local time 24:00–04:00, about 4–10 t h−1). High concentrations of SBTEX (above 1 ppb) occurred near the cities close to the I-10 interstate highway (Houston, Beaumont, Lake Charles, Lafayette, Baton Rouge, New Orleans, and Mobile) and other metropolitan cities (Shreveport and Dallas). High styrene concentrations were co-located with industrial sources, which contribute the most to the styrene emissions. The HAPI program successfully estimated missing emissions of styrene from the chemical industry. The change increased total styrene emissions by 22 %, resulting in maximum ambient concentrations increasing from 0.035 to 1.75 ppb across the model domain. The predicted SBTEX concentrations with imputed emissions present good agreement with observational data, with a correlation coefficient (R) of 0.75 (0.46 to 0.77 for individual SBTEX species) and a normalized mean bias (NMB) of −5.6 % (−24.9 % to 32.1 % for the individual SBTEX species), suggesting their value for supporting any SBTEX-related human health studies in the Gulf region. The SBTEX data were published at Zenodo (https://doi.org/10.5281/zenodo.7967541) (Wang et al., 2023), and the HAPI tool was also published at Zenodo (https://doi.org/10.5281/zenodo.7987106) (Wang and Baek, 2023).

Influence of Glow Discharge Plasma Treatment on Cashew Apple Juice’s Aroma Profile and Volatile Compounds

Cashew apple juice has a distinctive fruity aroma but contains an undesired balsamic/chemical note caused by the high concentration of styrene and other aromatic hydrocarbons. Cold plasma technology can induce chemical changes to fruit juices’ volatile compounds, improving the aroma of fruit juices. This study is aimed at evaluating the chemical effects of cold plasma on the volatile compounds and aroma of cashew apple juice, which is characterized by a complex mixture of compounds. Glow discharge plasma was applied to cashew apple juice, varying the plasma flow rate (10 to 30 mL/min) and processing time (10 to 20 min) at a constant voltage (80 kV). Plasma treatment induced several changes in the juice’s volatile compound composition, with a significant decrease in fatty acids and fatty acid esters (92%) and an increase in aldehydes (50%), alcohols (86%), and short-chain esters (21%). The primary reaction observed during plasma treatment was the internal scission of fatty acid and fatty acid esters, which formed short-chain esters and aldehydes. Further hydrogenation of aldehydes produced alcohols. The chemical changes induced by plasma treatment intensified cashew apple juice’s aroma by 28% while maintaining its aroma profile.

Styrene removal by low-temperature catalytic oxidation using Mn2O3/Al2SiO5

Highly efficient catalytic oxidation for the removal of volatile organic compounds (VOCs) is commonly accompanied by considerable energy demand to conduct the reaction at high temperature. Therefore, the development of low-temperature catalytic oxidation systems based on metal oxides has attracted widespread interest. In this study, we have assessed the performance of Mn2O3/Al2SiO5 in catalyzing the oxidation of styrene. Tests were conducted in a fixed-bed reactor with different loadings of the supported catalyst under different operating conditions (concentration of styrene, oxygen availability, space velocity, and temperature). The characteristics of the catalyst and the reaction kinetics have been studied in detail. The best catalytic activity was achieved with 38 wt% Mn2O3/Al2SiO5, which gave 95% styrene conversion (T95) at 298 °C. A space velocity of 5000 h−1 provided sufficient reaction time and favored the oxidation of styrene. The absence of O2 significantly suppressed styrene conversion to 25.4%, but the presence of just 1% O2 substantially enhanced its catalytic oxidation. A lower reaction temperature of 282 °C led to reduced performance of the catalyst, such that only 20% styrene conversion was achieved, which was due in part to extensive carbon deposition.

Pilot Study on Fire Effluent Condensate from Full Scale Residential Fires

AbstractStudies related to effluent produced by structure and vegetation fires often focus on gas phase or solid condensed phase, with limited treatment of liquid condensate generated as smoke cools to ambient. Recent post-fire human health concerns related to systemic human exposures to fire smoke and contamination of water distribution systems after wildland urban interface fires can be informed by understanding the chemical composition of liquid condensate resulting from large-scale fire experiments. In this pilot study, fire effluent (smoke) samples were continuously drawn from five different full-scale room-and-contents fire experiments, from which condensate was collected as the effluent cooled. Elevated concentrations of several volatile organic compounds (VOCs), including benzene, toluene, xylenes, styrene, naphthalene, and acetone along with several anions were detected in the acidic effluent. Many of these same VOCs have been identified in the air during firefighter safety experiments and in post-fire water distribution systems at levels that raise concern for human health. Benzene and naphthalene concentrations in the condensate were orders of magnitude above typical water quality standards and thus may directly contaminate large volumes of water. Peak benzene concentrations were similar to highest values reported from contaminated water distribution systems after wildfire events, though additional study is needed to understand the mechanisms by which this condensate may contribute to systemic contamination. Improved understanding of liquid condensate from fire effluent may be important to other areas of human and environmental health study, and some considerations are provided for future research.

Comparison of sampling methods for the determination of volatile organic compounds in consumer aerosol sprays

Many studies have evaluated the hazardous substances contained in various household chemical products. However, for aerosol spray products there is currently no international standard sampling method for use in a component analysis. The aim of this study was to develop an appropriate sampling method for the analysis of volatile organic compounds (VOCs) in consumer aerosol sprays. Two different sampling methods, spraying (into a vial) and perforating (and transferring the contents into a vial), were used to evaluate the levels of 16 VOC components in eight different aerosol spray products. All eight products contained trace amounts of hazardous VOCs, and a quantitative analysis showed that, for the same product, VOC concentrations were higher when spraying than when perforating. Using the spraying method, average toluene, ethylbenzene, p-xylene, o-xylene, and styrene concentrations were 1.80-, 2.10- 2.25-, 2.03-fold, and 1.28-fold higher, respectively, than when using the perforating method. The spraying method may provide more realistic estimates of the user's exposure to harmful substances and the associated health risks when using spray products. Of the two representative methods widely used to analyze harmful substances in consumer aerosol sprays, the spraying method is recommended over the perforating method for the analysis of VOCs.

Stress relaxation and thermal management in highly filled flexible styrene butadiene styrene copolymer‐tungsten composites for high‐energy radiation attenuation

AbstractA high loading of high‐density and high‐atomic‐number fillers are necessary to obtain desirable X‐ray attenuation characteristics from radiation shields. However, at high filler loadings, the mechanical and viscoelastic properties of polymers are severely impaired, posing a long‐term threat to the mechanical integrity and radiation protection, and the radiation shield temperature may increase after prolonged exposure to ionizing radiation, accelerating the aging of the polymer matrix. In addition, inadequate thermal conduction can make the user uncomfortable while using radiation shields for personal protection. Unfortunately, little attention has been paid to the viscoelastic, stress relaxation, and thermal conductivity‐related features of these densely loaded systems, despite the significant effect of these parameters on long‐term applications and user compliance. In the present work, two different styrene butadiene styrene (SBS) copolymers were used to develop SBS‐tungsten (W) composites. At 500 phr W loading, significant attenuation of X‐rays was achieved along with good tensile strength and elongation at break. The results indicate that the concentration of styrene in the SBS and W loading substantially affected the attenuation, mechanical and rheological properties, and tensile stress relaxation rates. The thermal conductivity increased by >100%, and after gamma irradiation, faster cooling was observed in the W‐loaded composites beyond 300 phr of W loading. The 40% styrene composite demonstrated superior heat transfer at high W loadings owing to the better dispersion and distribution of the W filler in the SBS matrix. Rheological results showed that SBS‐W composites with 30% styrene had a more pronounced Payne effect than those with 40% styrene. Stress relaxation and morphological analyses also revealed changes in the W dispersion in the SBS matrix depending on the styrene content.