Toluene Concentration Research Articles

Drug delivery in thermo-responsive silicone catheters by grafting of N-vinylcaprolactam using gamma radiation

Radiation-induced graft polymerization of poly(N-vinylcaprolactam) onto silicone catheters by direct irradiation method was studied. The effects of the irradiation dose, as well as the monomer concentration, on the grafting efficiency were studied. The conditions for achieving maximum grafting yield were observed at 30% of monomer concentration in toluene at 50 kGy. The graft polymerization was examined by different characterization methods, including measurements such as thermogravimetric analysis, infrared, water contact angle, and swelling. The temperature-responsive behavior of smart grafted copolymer was studied by swelling at different temperatures. Differently from pristine silicone catheter, the N-vinylcaprolactam-grafted catheters were able to load vancomycin and sustain the release for 30 h.Graphical abstract

Efficient toluene degradation using Bacillus subtilis biofilm-supported Mn–Ce/zeolite catalysts

This study investigated a new approach for synthesizing Bacillus subtilis biofilm-supported Mn–Ce/zeolite catalysts for the degradation of gaseous toluene. Four different metal oxide nano-catalysts (ZMn, ZMnCe-10%, ZMnCe-20%, and ZMnCe-30%) were synthesized with varying ratios of manganese (Mn) and cerium (Ce) on zeolite nanoparticles. TEM, SEM, XRD, BET, XPS, and EDX mapping were used to examine these four samples, as well as simple zeolite. Based on these analyses, the catalytic activity of the prepared samples ZMn, ZMnCe-10%, ZMnCe-20%, and ZMnCe-30% for the complete oxidation of toluene and toluene intermediate products were tested with Non-thermal plasma (NTP) technology in a dielectric barrier discharge (DBD) reactor. Among all, ZMnCe-20% showed the highest toluene degradation efficiency (89%) at low concentrations (200 ​ppm) and humidity (>50%). Later, highly efficient and hydrophobic nano-biocatalysts were prepared by combining B. subtilis biofilm wild-type (WT) and engineered B. subtilis biofilm EPS with ZMnCe-20% catalyst. EPS is the main component found in biofilm matrix and plays a key role in influencing properties such as biofilm stability, electron transfer, surface roughness and hydrophobicity. Compared to WT B. subtilis biofilm, EPS overexpressed B. subtilis biofilm showed stronger growth and development on ZMnCe-20% nanocatalyst. Moreover, the NTP system packed with ZMnCe-20%/biofilm (EPS+) nano-biocatalyst exhibited the highest toluene degradation activity (99%) with (83%) CO2 selectivity, (up to 50%) reduction in NOx concentration and complete ozone decomposition at (250 ​ppm) toluene concentrations and increased humidity (>90%). High-energy electrons generated in the NTP system break the C–H and C–C bond between the rings of the toluene molecule, forming several byproducts which are later reacted with active radical species such as O, OH, and O3 and further converted into final degradation products (CO2 and H2O). The results demonstrated successful biofilm development and growth on the ZMnCe-20% catalyst with advanced features such as superhydrophobicity, H2O resistance, improved surface roughness, and electron generation. In short, the study's approach combines bioengineering and material science to develop sustainable nano-biocatalysts for removing VOCs in industrial and environmental settings.

Water-Resistance-Based S-Scheme Heterojunction for Deep Mineralization of Toluene.

Deep mineralization of low concentration toluene (C7 H8 ) is one of the most significant but challenging reactions in photocatalysis. It is generally assumed that hydroxyl radicals (⋅OH) as the main reactive species contribute to the enhanced photoactivity, however, it remains ambiguous at this stage. Herein, a S-scheme ZnSn(OH)6 -based heterojunction with AlOOH as water resistant surface layer is in situ designed for tuning the free radical species and achieving deep mineralization of C7 H8 . By employing a combination of in situ DRIFTS and materials characterization techniques, we discover thatthe dominant intermediates such as benzaldehyde and benzoic acid instead of toxic phenols are formed under the action of holes (h+ ) and superoxide radicals (⋅O2 - ). These dominant intermediates turn out to greatly decrease the ring-opening reaction barrier. This study offers new possibilities for rationally tailoring the active species and thus directionally producing dominant intermediates via designing water resistant surface layer.

Water‐Resistance‐Based S‐Scheme Heterojunction for Deep Mineralization of Toluene

AbstractDeep mineralization of low concentration toluene (C7H8) is one of the most significant but challenging reactions in photocatalysis. It is generally assumed that hydroxyl radicals (⋅OH) as the main reactive species contribute to the enhanced photoactivity, however, it remains ambiguous at this stage. Herein, a S‐scheme ZnSn(OH)6‐based heterojunction with AlOOH as water resistant surface layer is in situ designed for tuning the free radical species and achieving deep mineralization of C7H8. By employing a combination of in situ DRIFTS and materials characterization techniques, we discover that the dominant intermediates such as benzaldehyde and benzoic acid instead of toxic phenols are formed under the action of holes (h+) and superoxide radicals (⋅O2−). These dominant intermediates turn out to greatly decrease the ring‐opening reaction barrier. This study offers new possibilities for rationally tailoring the active species and thus directionally producing dominant intermediates via designing water resistant surface layer.

Enhancing air treatment through controlled fabrication of transition metal-doped titanium dioxide nanocomposites for photocatalytic toluene degradation

Rapid industrial growth and urbanization have resulted in a significant rise in environmental pollution issues, particularly indoor air pollutants. As a result, it is crucial to design and develop technologies and/or catalysts that are not only cost-effective but also promising high performance and practical applicability. However, achieving this goal has been so far remained a challenging task. Herein, a series of transition metal M − TiO2 (M = W, Fe, Mn) nanocrystals was prepared for photocatalytic degradation of volatile organic compounds (VOCs), i.e., toluene. Of the nanocomposites tested, W–TiO2 showed significantly improved photocatalytic activity for VOC degradation under UV irradiation compared to the others. In particular, the optimized W dopant amount of 0.5 wt% resulted in the outstanding degradation performance of toluene (96%) for the obtained W–TiO2(0.5%) nanocomposite. Moreover, W–TiO2(0.5%) nanocomposite exhibited good stability for 32 h working under high toluene concentration (10 ppm) compared to the pristine TiO2. The current work demonstrates the potential usage of M − TiO2 nanocrystals, particularly W–TiO2(0.5%), as a promising photocatalyst for efficient VOCs degradation.

Enhanced toluene removal from aqueous solutions using reed straw-derived biochar

Abstract The escalating threat of pollutants, particularly aromatic hydrocarbons like benzene, toluene, ethylbenzene and xylene (BTEX), in aquatic environments necessitates effective remediation strategies. This study explores the potential of biochar derived from common reed (Phragmites australis) as a sustainable and multifaceted tool for the removal of toluene, a representative BTEX compound, from aqueous solutions. By harnessing reed straw as the precursor material for biochar production, this research showcases an environmentally friendly alternative to conventional disposal methods, such as incineration, offering the dual benefit of pollutant removal and carbon emissions reduction. The influence of pyrolysis temperature on biochar properties and its adsorption efficiency for toluene were rigorously examined, revealing a direct correlation between temperature and biochar’s pollutant sequestration capabilities. Results indicate that higher pyrolysis temperatures led to biochar (RB-750) with superior specific surface area (68.07 m2/g) and enhanced adsorption capabilities, demonstrating its potential as a powerful adsorbent in water treatment. The scanning electron microscope analysis revealed a complex, porous structure rich in active sites, validating the biochar’s suitability for pollutant adsorption. Optimal dosage was determined at 8 g/l, achieving an impressive toluene removal efficiency of 98.1%. Additionally, pH and initial toluene concentration significantly influenced removal efficiency. This study underscores the multifaceted potential of reed straw-derived biochar in combating water pollution while concurrently contributing to carbon emissions reduction through sustainable utilization of abundant wetland resources. Further research should delve into the impact of real-world conditions on its effectiveness, promising innovative solutions for environmental remediation efforts with a reduced carbon footprint.

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.

ЭКСПЕРИМЕНТАЛЬНЫЕ ИССЛЕДОВАНИЯ ВЛИЯНИЯ ТЕМПЕРАТУРЫ НА ПРОЦЕСС ПЕРЕРАБОТКИ ПОЛИСТИРОЛА В СРЕДЕ СВЕРХКРИТИЧЕСКОЙ ВОДЫ

Polystyrene waste is a serious environmental problem due to the large production volumes and non-biodegradable nature of this raw material. Provided that the high molecular weight polymer can be decomposed into useful low molecular weight hydrocarbons, polystyrene waste is considered as a highly valuable raw material. However, to date, the thermal processing of polystyrene is predominantly used in industry. The thermal processing of polystyrene includes pyrolysis. This method is energy-consuming and negatively affects the environment. The paper considers the hydrothermal method of polystyrene processing in supercritical water environment. This depolymerization process is carried out in a closed reactor where water serves as solvent, catalyst and reactant. As water approaches the critical point, it changes its properties such as: dielectric constant, density, heat and mass transfer characteristics. These significant changes allow supercritical water to induce rapid selective reactions to convert polystyrene to low molecular weight hydrocarbons. In this work experimental studies of polystyrene processing in supercritical water were carried out at temperatures T=375 - 425 0C, water volume equal to V=200 ml, during time τ=10 - 120 min. Hydrothermal processing of polystyrene in supercritical water leads to the formation of liquid phase, which was analyzed by chromatography-mass spectrometer Crystal 9000. The results of the analysis indicate the content of styrene, ethylbenzene, benzene, toluene, and naphthalene in the liquid phase. It was found that at temperature T=375 0C and time τ=10-15 min, a significant amount of styrene is formed. The possible mechanism of depolymerization of polystyrene in supercritical water was also considered in this work. As the time increases up to τ=120 min, at temperature T=375 0C, the formation of styrene decreases and the formation of toluene, benzene, ethylbenzene increases.

Catalytic combustion of toluene over cerium modified CuMn/Al2O3/cordierite monolithic catalyst

Catalytic combustion is an effective approach to remove volatile organic compounds, in which the development of highly active and durable catalyst is extremely crucial. Herein, a series of CuMnCex/Al2O3/cordierite monolithic catalysts were synthesized by using the ultrasonic-assisted impregnation method. The physicochemical properties were comprehensively characterized via the BET, XRD, SEM, EDX, H2-TPR, O2-TPD, XPS and EPR techniques. The results showed that the catalytic activity of CuMnCex/Al2O3/Cor for toluene combustion was strongly affected by the Ce content. The CuMnCe2/Al2O3/Cor monolithic catalyst showed the best catalytic activity with toluene conversion of 90% at 263 °C under toluene concentration of 1 g/L and space velocity of 78000 mL/(g·h). Meanwhile, the well-dispersed CeO2 in the CuMn matrix not only improved the content of oxygen vacancies and the mobility of oxygen species, but also enhanced the low-temperature reducibility of the catalyst. Moreover, the CuMnCe2/Al2O3/Cor monolithic catalyst exhibited an excellent stability in the long-term test and cycle ability test.

Analysing the effects of toluene percentages and exhaust gas re-circulation rates on spark-ignition engine performance and emissions

This study delves into the intricate dynamics of gaseous emissions in relation varying parameters in spark-ignition engines: gasoline-toluene blending ratios, exhaust gas re-circulation (EGR) rates, and spark timings. With increasing toluene concentrations, there was a consistent reduction in emissions, culminating in HC values of 67 ppm, CO at 0.6% volume, PM at 11 mg/m?, and NOx at 100 ppm for a 100% toluene blend. The implementation of EGR demonstrated its efficacy in mitigating NOx emissions, registering a decline to 60 ppm at a 30% EGR rate. However, the same augmentation in EGR rates witnessed an uptick in HC and CO emissions. Analysis of spark timings pinpointed an optimal advance of 30? CA bTDC at a 50% engine load, yielding minimized emissions. Conclusively, the research underscores the potential of fine-tuning engine parameters, such as fuel composition, EGR rates, and spark advance, to achieve a harmonious balance between engine efficiency and emission reductions. This study lays foundational data for further exploration and optimization in the realm of internal combustion engines.

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.

Enhancing indoor air quality and sustainable living in newly constructed apartments: insights from Dubai

This research paper examines Indoor Air Quality (IAQ) conditions in newly constructed apartments in Dubai to be more sustainable for residents to have healthier lifestyles. Enhanced airtightness and chemical-laden materials contribute to IAQ pollution in these buildings. The study aims to assess pollutant concentrations and variations based on building height. Measurements were conducted in 12 apartment units using the WHO’s IAQ assessment methodology. Most pollutants were within limits, but TVOC exceeded the Dubai Municipality’s standard, measuring at 2634.4 μg/m³, approximately nine times higher than the standard. HCHO (163.4 μg/m³) and toluene (551.4 μg/m³) were identified as significant pollutants with potential health effects. Analysis of pollutant concentrations based on building height revealed higher TVOC levels in upper areas, with 2,828 μg/m³ in the upper area compared to 2,443 μg/m³ in the lower area, indicating more severe indoor air pollution in Ethylbenzene and styrene also highest in upper areas, with ethylbenzene at 122 μg/m³ and styrene at 82 μg/m³ in the upper area, potentially due to elevated sources. Toluene and xylene concentrations were elevated in the middle area, with toluene at 574 μg/m³ and xylene at 321 μg/m³, likely influenced by materials and occupant activities. Benzene concentrations were consistent across all heights at 2.94 μg/m³, suggesting a common source. HCHO concentrations were relatively consistent but slightly higher in the middle and upper areas, with 171 μg/m³ in both, likely influenced by ventilation and emissions. While average pollutant concentrations met WHO standards, many units exceeded recommended limits, requiring targeted interventions. The study highlights the importance of addressing IAQ concerns and implementing strategies to reduce indoor air pollutants and improve ventilation. These findings contribute to IAQ knowledge in Dubai’s residential buildings, guiding policymakers, architects, and developers in effective policies and guidelines. Further research on seasonal variations and other IAQ factors is recommended for better understanding and long-term monitoring. Prioritizing IAQ in newly constructed apartments is crucial for healthier living in Dubai. The residential building sector can protect residents’ health by implementing appropriate measures while delivering upscale living experiences.

Indoor air quality and its determinants in underground shopping malls in Korea

Underground shopping malls (USMs) are often open or semi-open environments with interconnected passageways, resulting in the sharing of indoor air. However, indoor air quality (IAQ) within these spaces can vary due to many diverse emission sources. We investigated the relationships between IAQ and geographical areas, as well as IAQ and store types, within USMs, in Korea.In 2020, we studied 10 different USMs, with a total of 128 outlets. We conducted comprehensive IAQ assessments (including measurements of fine particles (PM2.5), aldehydes, and volatile organic compounds (VOCs)) in stores, passages, and outdoor areas. The stores were categorized into three types: clothing, fashion accessories, and food services. Additionally, we measured environmental factors such as CO2 levels and presence of storefront walls.PM2.5 levels were higher outdoors, whereas aldehyde and VOC levels exhibited elevations within passages and the interior of stores than in the outdoor environment. The store-to-passage ratios for PM2.5, individual aldehydes, and VOC concentrations ranged from 1.06 to 4.93. Formaldehyde and total VOC (TVOC) concentrations were found to be elevated in clothing and fashion accessory stores, whereas PM2.5 concentrations were more prominent in food service establishments. Specific individual compounds, including propionaldehyde, hexaldehyde, benzene, n-heptane, toluene, n-octane, xylene, d-limonene, n-undecane, n-dodecane, and ethylbenzene concentrations exhibited associations with store types. Multivariate regression models demonstrated positive associations between most aldehydes and VOCs with CO2 concentrations and presence of storefront walls.This study underscored variations within USMs based on area and store type. Aldehyde and VOC concentrations were notably higher in clothing and fashion accessory stores than in food service outlets; these elevations were closely linked to CO2 levels and presence of storefront walls. These findings suggest that monitoring CO2 levels within USM stores, optimizing air-conditioning systems, and designing future stores without storefront walls can collectively contribute to an overall improvement of IAQ within USMs.

A rhodanine modified poly-triarylamine dye function as a hole transport layer for inverted perovskite solar cells

Multifunctional modifications for the perovskite layer are essential for achieving low-cost, high performance and stability of the inverted perovskite solar cells (PSCs). Herein, a Rhodanine modified poly-triarylamine dye, VN7, is developed and functioned as a hole transport layer (HTL) contact along with a passivation material and infiltration regulating layer for perovskite layer to overcome the positive electrode interface issues. The results of optics, electricity, and interface contact characterizations on VN7 indicated the functions of the matched energy levels vs. perovskite, interface traps passivation, and interface contact improvement. By introducing VN7 layer from series of different concentrations in toluene, obtained a relatively optimized concentration 4 mg/mL, achieving a power conversion efficiency (PCE) of 19.33 %, with a Voc of 1.10V, Jsc of 21.82 mA cm−2, and FF of 80.57 %, respectively.

BTEX OCCURRENCE IN THE INDOOR AIR OF BEAUTY SALONS – PRELIMINARY RESEARCH

This study aimed to identify and carry out a preliminary assessment of the health exposure ofemployees working in beauty salons to selected compounds from the BTEX group. The selectedsalons were all situated in the Silesian Voivodeship, recognized as one of the most polluted regionin Poland and European hot spot area in terms of air pollution. Measurements encompassed weeklymonitoring of marked BTEX compounds in beauty salons specializing in nail styling, hairdressingand cosmetics. As an internal substrate, measurements were also taken in a children’s hairdressingsalon where no chemical products were used; also a weekly measurement was performed foroutdoor air to look for outdoor background BTEX concentrations.For BTEX determination, Tenax sorbent tubes insertion was employed. The collected samples wereanalysed using a Clarus 500 gas chromatograph with a flame ionization detector (FID) connectedto a Perkin Elmer Turbo-Matrix 100 thermal desorber . Toluene concentrations were found to benotably elevated, reaching up to 73.19 μg/m in adult hairdresser salons, representing an orderof magnitude higher than that found in indoor background (children’s hairdresser) and outdoorbackground. Importantly, the concentrations of the measured BTEX compounds remained belowthe acceptable levels defined by the National Institute for Occupational Safety and Health (NIOSH).Among the individual BTEX compounds, nail treatment salons exhibited the highest meanconcentrations for benzene; m,p-xylene; n-propylbenzene; styrene; isopropylbenzene; and1,3,5-trimethylbenzene. Conversely, cosmetic salons registered the highest mean concentrationof ethylbenzene; o-xylene; and n-propylbenzene. The results indicate a chronic exposure ofsalon employees to the tested compounds, with heightened levels particularly noticeable amongindividuals with extensive professional experience. These findings underscore the importance ofongoing monitoring and occupational health measures in beauty salons, emphasizing the potentialrisks associated with long-term exposure to BTEX compounds.

Identification of Sars-Cov-2 related volatile organic compounds from face masks

This study aims to identify SARS-CoV-2-related volatile organic compounds (VOCs) of the exhaled breath from face masks. Face masks collected from SARS-CoV-2 patients (n = 30) and the control group (n = 11) were analyzed to detect VOCs in the exhaled breath using the Headspace-Gas Chromatography Mass Spectrometry. Significant increases in concentrations of toluene, hexadecane, and phenol were detected in the face masks belonging to patient groups (p < 0.001). Clinical significance was further found in isobutyric acid levels considering Cohen's d value (p = 0.070). The findings of this study suggest that monitoring toluene, hexadecane, phenol, and isobutyric acid could provide considerable support in rapid screening of SARS-CoV-2.

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).

Removal of toluene via non-thermal plasma generated by applying rare-earth tungsten electrode and nanosecond pulsed power supply.

The objective of this investigation is to evaluate the characteristics associated with degradation of toluene through the utilization of non-thermal plasma (NTP) generated via application of a low-work-function electrode and nanosecond pulsed power supply. Initially, a comparative analysis is made between toluene removal efficiency utilizing the low-work-function electrode and that achieved with the conventional stainless-steel electrode. The outcomes demonstrate that NTP generated by the low-work-function electrode exhibits markedly superior removal efficiency for toluene in comparison to the stainless-steel electrode operating at the same voltage. Subsequently, the impacts of voltage, pulse frequency, and initial concentration of toluene on the removal efficiency and production of by-products are investigated. It is found that as the voltage and frequency increase, the removal efficiency also increases, and a maximum toluene removal efficiency of 87.2% is achieved at a voltage of 12,000V and pulse frequency of 2000Hz. The removal efficiency first increases and then decreases with increasing toluene initial concentration. The investigation also finds that energy yield is negatively correlated with voltage and pulse frequency and positively correlated with the initial concentration. Finally, the reaction products were subjected to quantitative analysis using GC-MS. Based on the analysis results, potential reaction pathways are inferred.

High efficiency photothermal synergistic degradation of toluene achieved through the utilization of a nickel foam loaded Pt-CeO2 monolithic catalyst

Recent research highlights the pressing need for innovative and practical oxidation degradation technologies for volatile organic compounds (VOCs). In this study, a monolithic catalyst was successfully developed by loading Pt-CeO2 onto nickel foam (NF) matrix through hydrothermal and reduction methods. The photothermal catalytic performance was investigated at room temperature for varying Pt content, toluene concentration, light source type, and water content. Remarkably, the toluene removal efficiency and CO2 selectivity stabilized at 98.8 % and 74.6 %, respectively, within less than 10 min of light activation. The d-d transition thermal effect of CeO2 and plasma effect of Pt enhanced light-to-heat conversion and active free radical generation (•O2– and •OH) through light absorption, respectively. The NF matrix's excellent thermal conductivity ensured a rapid increase in catalyst temperature upon visible light irradiation, reaching 173 °C. The study demonstrated that both the Mars-van Krevelen (Mvk) oxidation process, driven by temperature increase from near-infrared (NIR) absorption, and the free radical oxidation process, induced by higher energy illumination, synergistically contributed to toluene decomposition and mineralization. The catalyst's morphology, physical and chemical properties, surface synergistic oxidation process involving gaseous oxygen and free radicals, and toluene degradation pathway were thoroughly analyzed. We believe that this coexistence of thermocatalytic and photocatalytic mechanisms in a monolithic catalyst driven by renewable solar energy holds significant potential for practical applications and warrants further exploration.

Influence of static pressure on toluene oxidation efficiency in groundwater by micro-nano bubble ozonation

Micro-nano bubble ozonation has been widely applied in the purification of drinking water due to its superior characteristics such as high mass transfer rate and long resistance time. However, its application in groundwater remediation is limited, partially due to the unclear effect of static water pressure on the oxidation efficiency. This study constructed a batch reactor to investigate the influence of static pressure on toluene oxidation by ozone micro-nano bubble water. To achieve constant pressure, weight was added above the mobile reactor roof, and the initial concentrations of toluene and dissolved ozone were 1.00 mg L−1 and 0.68 mg L−1 respectively. Experimental results demonstrated that as the static water pressure increased from 0.0 to 2.5 m, the average microbubble diameter decreased significantly from 62.3 to 36.0 μm. Simultaneously, the oxidation percentage of toluene increased from 40.3% to 58.7%, and the reaction rate between toluene and hydroxyl radical (OH·) increased from 9.3 × 109 to 1.39 × 1010 M−1 s−1, indicating that the shrinkage of micro-nano bubbles generated an abundance of OH· that quickly oxidized toluene adsorbed at the bubble interface. A greater enhancement of oxidation efficiency for nitrobenzene, as compared to p-xylene, was observed after the addition of 2.5 m water pressure, which verified the larger contribution of OH· under static pressure. Although the improvement of oxidation efficiency was reduced under acid and alkaline environments, as well as in practical groundwater matrices, the overall results still demonstrated the promising application of micro-nano bubble ozonation in groundwater remediation.