Uniform platinum nanoparticles loaded on Universitetet i Oslo-66 (UiO-66): Active and stable catalysts for gas toluene combustion

Highly dispersed Pt nanoparticles supported UiO-66 catalysts were successfully prepared by the incipient wetness impregnation method. Their thermal catalytic performances were evaluated by toluene degradation. The physicochemical properties of the samples were characterized using a series of characterization methods. The catalytic activity of catalysts remained essentially unchanged in the high weight hourly space velocity, stability and water resistance test, which also indicated good catalytic performance. In the reusability test, the catalytic performance was found to be enhanced after the reaction, because of the catalyst might follow a Pt⁰-PtO synergistic catalytic mechanism (similar to Mars-van Krevelen mechanism) and there was a phase transition between Pt⁰ and PtO during the reaction. Firstly, the toluene adsorbed on the catalyst surface was oxidized by the activated lattice oxygen of the PtO. Then, consumption of oxygen atoms led to formation of oxygen vacancies, and finally the molecular oxygen adsorbed by Pt⁰ was activated and passed to the PtO to supplement the oxygen vacancies, forming a redox cycle. In addition, the possible catalytic oxidation mechanism of toluene was also revealed.

Promote the activation and ring opening of intermediates for stable photocatalytic toluene degradation over Zn-Ti-LDH

Improving the selectivity of photocatalysis and reducing the generation of toxic by-products are the two key challenges for the development of highly efficient and stable photocatalysts. In this work, it was revealed that Zn-Ti-layered double hydroxide (ZT-LDH) photocatalyst, which generated less intermediates, showed better toluene degradation efficiency (removal ratio, 75.2%) and stability, compared with P25 (removal ratio, 10.9%). During the photocatalytic toluene degradation, benzaldehyde and benzoic acid were the main intermediates existed in the gas phase and on the surface of the catalyst, respectively. By combining experiments with theoretical calculation, it was found that the hydrogen atoms on the hydroxyl groups in the LDH would selectively attract the oxygen atoms in the carbon-oxygen double bond of the two major intermediates, facilitating their adsorption and activation on ZT-LDH. Besides, the surface electronic structure of ZT-LDH was demonstrated to facilitate the ring-opening reaction of the two major intermediates, eventually maintaining high activity and stability. This work could provide new molecular perspectives for understanding the photocatalytic reactions in VOCs degradation and developing efficient and stable photocatalysts.

ACUTE EXPOSURE TO ABUSE-LIKE CONCENTRATIONS OF TOLUENE INDUCES INFLAMMATION IN MOUSE LUNGS AND BRAIN

Toluene is an aromatic hydrocarbon commonly abused by young adolescents for its central nervous system depressant effects. While toluene's pharmacological effects at high concentrations are relatively well known, few studies have assessed toluene's effects on lung and brain tissues. The present study characterized the pathological effects of acute inhaled toluene exposure in the lungs and brains of male Swiss-Webster mice (N = 68). Using a static vapor exposure chamber, mice (PND 28) received a single 30-min toluene administration (0, 1000, 2000, or 4000 ppm). Lung and brain tissues were extracted 24 hrs post-exposure. Histology results revealed significant changes in the morphology lung tissue (e.g., irregular cellular architecture) with the 2000 and 4000 ppm exposures expressing greater signs of pathology than control 0-ppm exposure. Markers of immune system activity (F4/80 and Ly-6G) and cellular proliferation (Ki-67) in the lung revealed no significant differences. Additionally, brain tissues were analyzed for changes of astrogliosis (GFAP) and oxidative stress (GPx). GFAP showed increased astrogliosis in the striatum with 2000 ppm toluene showing significantly higher expression than control (p < 0.05), and a marginal effect in the hippocampus. No other markers showed significant changes. The increased signs of inflammation and cellular damage suggest that exposure to a single high concentration of toluene, typical of abuse, are capable of producing pathology in both lung and brain tissue.

C-dot doping for enhanced catalytic performance of TiO2/5A for toluene degradation in non-thermal plasma-catalyst system

Non-thermal plasma (NTP) is gaining attention as a powerful tool to induce various reactions. The combination of NTP with catalysts has been successfully used to degrade volatile organic compounds (VOCs) for pollution control. In this study, a series of TiO₂-C/5A catalysts, synthesized by carbon dots (C-dots) that decorate TiO₂ by sol-gel and wetness impregnation methods, were incorporated with a dielectric barrier discharge (DBD) reactor in a single-stage structure to degrade toluene at atmospheric pressure and room temperature. A proton-transfer reaction mass spectrometer and a CO₂ analyzer were used to monitor the concentration variations of organic by-products and CO₂ online. The effects of input power, mass ratio of C-dots/TiO₂ (TiO₂/5A (0 wt%), TiO₂-C1/5A (2.5 wt%), TiO₂-C2/5A (5 wt%), TiO₂-C3/5A (10 wt%)), gas flow rate, initial concentration of toluene on the toluene degradation efficiency, and CO₂ selectivity were studied. The plasma-catalyst hybrid system could effectively improve the energy efficiency and reaction selectivity, attaining a maximum toluene degradation efficiency of 99.6% and CO₂ selectivity of 83.0% compared to 79.5% and 37.5%, respectively, using the conventional plasma alone. Moreover, the generation of organic by-products also declined dramatically, averaging only half as much in plasma alone. The results also indicated that the appropriate amount of C-dot doping could greatly improve the catalyst efficiency in the hybrid plasma system. This is because the interaction between C-dots and TiO₂ favors the formation of photoelectron holes and reduces the energy band gap and the recombination rate of photogenerated electron holes, which facilitates the generation of more active species on the catalyst surface, thereby leading to a more effective degradation reaction. These observations will provide guidance for the interaction studies between NTP and catalysts, not only for the exploration of new chemical mechanisms of aromatic compounds, but also for the screening of favorable materials for the desired reactions.

A case study: Chemical health risk assessment in three footwear small industries in Bogor-Indonesia year 2019

OBJECTIVE

This study aimed to analyse the health risks related to the use of chemicals among workers in small footwear factories.

METHODS

This was a descriptive case study conducted in three selected small footwear factories located in Ciomas, Bogor, Indonesia. The assessment was conducted using the chemical health risk assessment method by the Department of Safety and Health Malaysia Year 2018.

RESULTS

Results showed that the level of risk of chemicals through inhalation fell on the moderate and high-risk categories, indicating that high exposure could lead to carcinogenic effects. Dermal exposure was categorised as moderate risk, causing such health effects as skin and eye irritation.

CONCLUSION

Factory X, Y, and Z have been found to have a significant risk of hazardous chemical exposure (i.e., benzene and toluene), specifically at the glueing stations, either from inhalation or dermal contact.

Catalytic ozone oxidation toluene over supported manganese cobalt composite: influence of catalyst support

In this study, the manganese cobalt composite (Mn-Co)-loaded SiO₂, MgO, TiO₂, γ-Al₂O₃ and silicalite-1 were prepared by ultrasonic complexation method. The catalysts were characterized by XRD, BET, SEM, TEM, H₂-TPR and XPS, and the activity of catalytic oxidation of toluene was evaluated. It was found that Mn-Co loaded γ-Al₂O₃ (Mn₂CoO_x/γ-Al₂O₃) exhibited excellent catalytic activity. When the gas hour space velocity (GHSV) was 45,000 h^-1, the removal rate of toluene reached 91.2% within 5.5 h, and the selectivity of CO₂ was 71.10% at ambient temperature. The operation of Mn₂CoO_x/γ-Al₂O₃ at different temperatures was investigated, and the better toluene removal efficiency more than 80% after reacting 9h was obtained at 50 °C. The characterization results showed that better catalytic activity is related to smaller grain size, higher Mn³⁺/Mn⁴⁺ values and the relative content of active oxygen species (O_II + O_III). Increased amounts of low state species easily led to the imbalance of the catalyst surface charge and promoted the formation of more oxygen vacancies.

Volatilization process of toluene from contaminated soil under consideration of co-existence of pore water

The volatilization process of contaminants has been shown to play an important role in remediation of VOC-contaminated soils. The aim of this paper is to study the volatilization characteristics of both toluene and water from soil, and to evaluate their interaction mechanism under different conditions. A test system is developed to measure mass loss of contaminants and water from soil by volatilization. It was found that basically the volatilization process could be divided into two stages in clay and one stage in sand. Two main influential mechanisms of water on the volatilization of toluene include molecules' competitive adsorption and blocking of volatilization channels. In addition, the evaporation process of water was restricted by volatilization of toluene. Volatilization rate of toluene would increase with the increase of water content when the water content was low. But it would decrease with the increase of water content when the water content was higher than 15% in clay. In addition, there existed an optimal water content (15%) under which the maximum volatilization rate could be achieved.

Enhancing effect of NO2 on the formation of light-absorbing secondary organic aerosols from toluene photooxidation

Aromatic hydrocarbons are one of the major precursors of atmospheric brown carbon (BrC) and both abundantly co-exist with NO_x in the urban atmosphere especially in winter haze period. However, the impact of NOx on the formation of BrC derived from aromatic hydrocarbons is still not fully understood. In this study, the yield and light absorption of secondary organic aerosols (SOA) from toluene photooxidation under various nitrogen oxides (NO₂) levels were investigated by using a 5 m³ photooxidation smog chamber. A trend of increase at first and then decrease in the SOA yield with an increasing NO₂ concentration was observed. The acid-catalyzed heterogeneous reactions lead to the increase of SOA yield in the low-NO₂ regime. The formation of low-volatility species might be suppressed at high-NO₂ conditions is responsible for the decreased SOA yield. In contrast, light absorption and mass absorption coefficient (MAC) of the toluene-derived SOA continuously increased with the increasing NO₂ concentrations. HR-ToF-AMS results showed that nitrogen-containing organic compounds (NOCs) are the main species that lead to the increase of the SOA light absorption. The ratio of CHN family to the total NOCs, which are derived from the nitro compounds, also increased dominantly with the increasing NO₂ levels and accounted for more than half of the total NOCs when the NO₂ concentration increased to 495 ppbv, indicating that nitro compounds rather than organic nitrates are the major light-absorbing species and preferably formed in the toluene oxidation process.

Current progress on catalytic oxidation of toluene: a review

Toluene is one of the pollutants that are dangerous to the environment and human health and has been sorted into priority pollutants; hence, the control of its emission is necessary. Due to severe problems caused by toluene, different techniques for the abatement of toluene have been developed. Catalytic oxidation is one of the promising methods and effective technologies for toluene degradation as it oxidizes it to CO₂ and does not deliver other pollutants to the environment. This paper highlights the recent progressive advancement of the catalysts for toluene oxidation. Five categories of catalysts, including noble metal catalysts, transition metal catalysts, perovskite catalysts, metal-organic frameworks (MOFs)-based catalysts, and spinel catalysts reported in the past half a decade (2015-2020), are reviewed. Various factors that influence their catalytic activities, such as morphology and structure, preparation methods, specific surface area, relative humidity, and coke formation, are discussed. Furthermore, the reaction mechanisms and kinetics for catalytic oxidation of toluene are also discussed.

Captopril and losartan attenuate behavioural sensitization in mice chronically exposed to toluene

Inhalants are consumed worldwide for recreational purposes. The main component found in many inhalants is toluene. One of the most deleterious behavioural effects caused by chronic exposure to inhalants is addiction. This response has been associated with activation of the mesolimbic dopaminergic pathway, and it is known that the renin angiotensin system plays a role in the modulation of this dopaminergic system. In the present work, we hypothesize that blockade of the RAS with angiotensin converting enzyme inhibitors or angiotensin II type 1 receptor blockers is able to attenuate the addictive response induced by toluene. We exposed mice to toluene for four weeks to induce locomotor sensitization. In the second phase of the work, captopril or losartan were administered for 20 days. Subsequently, the expression of behavioural sensitization was evaluated with a toluene challenge. To exclude false associations between the observed responses and treatments, motor coordination and blood pressure were analysed in animals treated with captopril or losartan. At the end of the behavioural studies, animal brains were harvested and Ang II/Ang-(1-7) and Ang-(1-7)/Ang II ratios were analysed in the nucleus accumbens (NAc) and prefrontal cortex (PFCx). The results showed that toluene induced behavioural sensitization, while captopril or losartan treatment attenuated the expression of this response. No significant differences were observed in motor coordination or blood pressure. Repeated toluene administration decreased Ang-(1-7)/Ang II ratio in the PFCx. On the other hand, treatment with captopril or losartan decreased the Ang II/Ang-(1-7) ratio and enhanced the Ang-(1-7)/Ang II ratio in the NAc. This work suggests that blockade of RAS attenuates the toluene-induced behavioural sensitization.

Exploring the link between adolescent inhalant misuse and suicidal behaviour: a behavioural toxicology perspective

Adolescent inhalant misuse has a known association with suicidal thoughts and behaviour. This association persists even after inhalant misuse has ceased. Previous studies have hypothesised that this association may derive from socioeconomic disadvantage or vulnerability, and potentially mediated by impulsivity. This association may also be due to the central nervous system depressant effects of inhalants. This review takes a behavioural toxicology perspective, focussed particularly on the serotonergic system and the Hypothalamic-Pituitary-Adrenal (HPA) axis, as potential links between adolescent inhalant misuse and suicidal behaviour. The challenges of bridging the pre-clinical and clinical literature in this area are discussed, along with promising avenues for future research; ultimately aimed at reducing suicide risk in a vulnerable adolescent population group.

Synergistic effect of adsorption and photocatalysis for the degradation of toluene by TiO2 loaded on ACF modified by Zn(CH3COO)2

Activated carbon fiber (ACF) was modified by Zn(NO₃)₂, ZnCl₂, and Zn(CH₃COO)₂), respectively, and then, TiO₂ was loaded on the modified ACFs. The adsorption and photocatalysis performance were explored through the removal of toluene, and TiO₂/ACF-_Ac modified by Zn(CH₃COO)₂) with the best toluene degradation performance was selected. The characterization results of a scanning electron microscope (SEM), X-ray diffraction spectra (XRD), and Fourier transform infrared spectrometer (FTIR) indicated that the samples were rough, and TiO₂ was mainly loaded on the surface containing large amount of oxygen-containing functional groups in anatase phase. An ultraviolet-visible diffuse reflectance spectrophotometer (UV-vis DRS) revealed that the catalyst enhanced the light response range. The photoelectric chemical experiment results demonstrated that the modified ACFs remarkably improved the charge transmission and the separation efficiency of electrons and holes. The adsorption saturation time reached 40 h and toluene photodegradation rate was 70%. Four toluene degradation intermediate products were determined by GC-MS, and the removal mechanism of toluene by TiO₂/ACF-_Ac was discussed.

Evaluation of the absorption performance of new compound absorbents for toluene under extremely high load

Absorption is an effective way to control volatile organic compound (VOC) industrial air pollution, and the key variable in this process is the selection of suitable liquid absorbents to absorb as many organic pollutants as possible. The objective of this study was to prepare a series of high-efficiency absorbents with different proportions of vegetal oil, mineral oil, and waste engine oil, which can be used for toluene absorption. The absorption efficiency (AE), saturated absorption (SA), and effective absorption time (EAT) of various absorbents were systematically analyzed. The results showed that when the inlet concentration of toluene was 8000 mg/m³ and the inlet flow was 1 L/min, the SA capability of vegetal oil, mineral oil, and waste engine oil was 7.15, 12.43, and 18.16 mg/g, respectively. With the 4000 mg/m³ inlet concentration, the SA of the absorber which was made in the ratio of 2:3:1 was increased to 50.93 mg/g. According to the thermodynamic equilibrium and absorption results, it is proved that the influence of the composition of the absorbent on absorption is greater than viscosity. It is also to be noted that the AE of the composite absorbent can still reach more than 80% after three times of heating and air purification.

Twisted bilayer arsenene sheets as a chemical sensor for toluene and M-xylene vapours - A DFT investigation

2D (two-dimensional) materials are emerging in today's world. Among the 2D materials, arsenene sheets are prominently used as chemical and biosensors. In the present work, the twisted bilayer arsenene sheets (TB-AsNS) are used to adsorb toluene and M-xylene vapours. Moreover, the band gap of pristine TB-AsNS is calculated to be 0.437 eV. Besides, the surface adsorption of toluene and M-xylene vapours modify the electronic properties of TB-AsNS noticed from the band structure, density of states, and electron density difference diagrams. The surface assimilation of target toluene and M-xylene on TB-AsNS falls in the physisorption regime facilitating the adsorption and desorption of molecules. Also, the charge transfer analysis infers that TB-AsNS acts as acceptor and target molecules play as donors. The findings support that TB-AsNS can be used as a sensing medium towards M-xylene and toluene.

Achieving toluene efficient mineralization over K/ɑ-MnO2via oxygen vacancy modulation

Oxygen vacancy plays an important role in adsorption and activation of oxygen species and therefore promotes the catalytic performance of materials in heterogeneous oxidation reactions. Here, a series of K-doped ɑ-MnO₂ materials with different K loadings were synthesized by a reproducible post processing process. Results show that the presence of K⁺ enhances the reducibility and oxygen vacancy concentration of ɑ-MnO₂ due to the break of charge balance and the formation of low valence Mn species. 4-K/MnO₂ material exhibits the highest toluene oxidation activity and satisfied long-term stability and water resistance owing to its superior reducibility and abundant surface absorbed oxygen (O_ads). In situ DRIFTS demonstrate that O_ads greatly accelerates toluene dehydrogenation rate and promotes benzoate formation, enhancing the activation and decomposition of toluene molecules. Moreover, the CC cleavage of benzene ring (forming maleic anhydride) is the rate-determining step of toluene oxidation, which can be easily occurred over 4-K/MnO₂.

Microwave-assisted synthesis of manganese oxide catalysts for total toluene oxidation

Oxygen vacancy on the heterogeneous catalyst is of great importance to the catalysis of volatile organic compound (VOC) oxidation. Herein, microwave radiation with special energy-excitation is successfully utilized for the post-processing of a series of manganese oxides (MnO_x) to generate oxygen vacancies. It is found that the MnO_x catalyst with 60 min of microwave radiation demonstrates higher activity for toluene oxidation with a T_50% of 210 °C and a T_100% of 223 °C, which is attributed to the higher concentration of oxygen vacancies derived from the rich phase interface defects resulted from the microwave radiation. Furthermore, the Mn-MW-60 catalyst possesses excellent thermal stability and water vapor tolerance even under 20 vol% H₂O atmospheres within 60 h. In situ DRIFTS analysis verifies that both surface and lattice oxygen species simultaneously participate the oxidation process, and all reactions over different environments follows two different pathways. Meanwhile, it is proposed that those oxygen vacancies derived from microwave radiation could facilitate the rate-controlling step of opening the aromatic ring based on the electron back-donation, thereby leading to the increment of catalytic activity.

Synthesis of N-doped hierarchical porous carbon with excellent toluene adsorption properties and its activation mechanism

Typical organic pollutants from coal-combustion flue gas such as volatile organic compounds (VOCs) need to be effectively controlled. This work synthesized a series of nitrogen-doped hierarchical porous carbons (NHPCs) by one-step activation with various proportions of cellulose, (NH₄)₂C₂O₄ and KHCO₃/NaHCO₃. The NHPCs have a high specific surface area and pore volume up to 2816 m²/g and 1.413 cm³/g as well as a hierarchical porous structure with micro-meso-macropores distribution. The dynamic adsorption tests of toluene at 600 ppm showed that NHPCs have a high adsorption capacity up to 585 mg/g (NHPC(K)131), this was about 3 times more than that of AC (208 mg/g), and is a better absorbent compared to many other carbon adsorbents. The porous characteristics and toluene adsorption properties of NHPCs improved along with the fluctuation of the proportions of raw materials and active agents. The micropore size of the material is the main factor that affecting the toluene adsorption capacity. The analysis of toluene dynamic adsorption breakthrough curves revealed that NHPCs had great toluene adsorption kinetics with high adsorption rate constants and short mass transfer zone. The excellent toluene adsorption kinetics of NHPCs can be attributed to the hierarchical porous structure. The abundant 2-10 nm mesopores and macropores of NHPCs act as mass transfer channels for toluene molecules. The XPS analysis showed that the NHPCs have nitrogen doping up to 6.71% (NHPC(Na)161) and they effectively promote toluene adsorption. The nitrogen doping mechanism can be attributed to the reactions between cellulose pyrolysis substances and NH₃ which decomposed from (NH₄)₂C₂O₄. Moreover, the pore forming reactivity of KHCO₃ is better than that of NaHCO₃ in the NHPCs activation process.

Defect engineering-induced porosity in graphene quantum dots embedded metal-organic frameworks for enhanced benzene and toluene adsorption

The emerging environmental issues necessitate the engineering of novel and well-designed nanoadsorbents for advanced separation and purification applications. Despite recent advances, the facile synthesis of hierarchical micro-mesoporous metal-organic frameworks (MOFs) with tuned structures has remained a challenge. Herein, we report a simple defect engineering approach to manipulate the framework, induce mesoporosity, and crease large pore volumes in MIL-101(Cr) by embedding graphene quantum dots (GQDs) during its self-assembly process. For instance, MIL-101@GQD-3 (V_meso: 0.68 and V_tot: 1.87 cm³/g) exhibited 300.0% and 53.3% more meso and total pore volume compared to those of the conventional MIL-101 (V_meso: 0.17 and V_tot: 1.22 cm³/g), respectively, resulting in 1.7 and 2.8 times greater benzene and toluene loading at 1 bar and 25 °C. In addition, we found that MIL-101@GQD-3 retained its superiority over a wide range of VOC concentrations and operating temperature (25-55 °C) with great cyclic capacity and energy-efficient regeneration. Considering the simplicity of the adopted technique to induce mesoporosity and tune the nanoporous structure of MOFs, the presented GQD incorporation technique is expected to provide a new pathway for the facile synthesis of advanced materials for environmental applications.

Continuous Flow Acylation of (Hetero)aryllithiums with Polyfunctional N,N-Dimethylamides and Tetramethylurea in Toluene

The continuous flow reaction of various aryl or heteroaryl bromides in toluene in the presence of THF (1.0 equiv) with sec -BuLi (1.1 equiv) provided at 25 °C within 40 sec the corresponding aryllithiums which were acylated with various functionalized N,N-dimethylamides including easily enolizable amides at -20 °C within 27 sec, producing highly functionalized ketones in 48-90% yield (36 examples). This method was well suited for the preparation of α-chiral ketones such as naproxene and ibuprofen derived ketones with 99% ee . A one-pot stepwise bis-addition of two different lithium organometallics to 1,1,3,3-tetramethyurea (TMU) provided unsymmetrical ketones in 69-79% yield (9 examples).

Facile synthesis of Pt-Ce0.63Zr0·37O2-Y catalysts and the application in catalytic oxidation of toluene

In this work, a series of Pt-Ce_0.63Zr_0·37O₂-Y catalysts were prepared by unique simple mechanical mixing method. The catalytic activity of these catalysts for toluene oxidation was investigated. The physicochemical properties of the catalysts were characterized by XRD, ICP-MS, SEM, TEM, XPS and N₂ sorption. Pore size distribution was analyzed according nitrogen adsorption and desorption isotherms. The catalytic results showed that using NaY as support for Pt-Ce_0.63Zr_0·37O₂-Y could enhance the conversion of toluene during the oxidation process in comparison with HY. Further mixing cerium zirconium solid solution with Pt-NaY can improve the oxidation catalytic property of these catalysts. The conversion of toluene over Pt-Ce_0.63Zr_0·37O₂-NaY reached more than 90% at 200 °C. High catalytic stability was obtained for toluene oxidation over Pt-Ce_0.63Zr_0·37O₂-NaY. Platinum, cerium and zirconium can be uniformly dispersed on Y zeolite with small particle size by simple mechanical synthesis. The effect of drying methods on catalytic activity and hydrothermal stability of catalysts were also investigated in this research.

Development of a feedback control system for a differential biofilter degrading toluene contaminated air

In this study, a proportional - integral feedback control system was implemented on a lab-scale differential biofilter to control the gas phase toluene concentration in the soil bed through online manipulation of the inlet toluene concentration. The feedback control system was based on a cascade controller that manipulated the setpoint of an air bath diffusion system to manipulate the inlet toluene concentration. The controller performed well for toluene concentrations in the reactor of 10 - 300 ppm for both setpoint changes and disturbance rejections; however, the system was nonlinear requiring different tuning parameters at different outlet concentrations. Feedback control of the toluene concentration in the differential reactor was used to explore the impact of concentration on start-up and long-term biofilter operation in a rigorous fashion. Starting at an reactor concentration of 20 ppm and then increasing to 65 ppm increased the toluene removal rate (33 ± 1.6 g m^-3h^-1) compared to starting the reactor at an outlet concentration of 81 ppm before settling at 65 ppm (42 ± 0.9 g m^{- 3}h^-1). The toluene removal rate increased with increasing outlet toluene concentration and then eventually decreased when reaching the inhibitory toluene concentration (ranged from 80 to 250 ppm).

The improved activity of Co3O4 nanorods using silver in the catalytic oxidation of toluene

Co₃O₄ nanorods with diameters of ~0.15 μm and lengths of ~1 μm were prepared using a hydrothermal method via the assembly of microcrystals and tested in the catalytic oxidation of toluene. The catalytic performance of Co₃O₄ nanorods was improved by the addition of Ag at various concentrations, and the 7% Ag/Co₃O₄ catalyst achieves a toluene conversion of 90% at 256 °C with a space velocity of 78,000 mL g^-1 h^-1, which is much lower than that of the pristine Co₃O₄ (269 °C). The addition of Ag promoted the activation of the surface oxygen species and the formation of more oxygen vacancies, improving the relative low-temperature reducibility of Co₃O₄, which is favorable for toluene oxidation. Moreover, the 7% Ag/Co₃O₄ catalyst showed an excellent stability for toluene oxidation at 250 and 260 °C for 50 h under the same conditions.

An alternative method to assess permeation through disposable gloves

Previously, we have demonstrated the capability of activated charcoal cloth (ACC) to assess dermal exposure to VOCs. Here we investigated whether ACC patches can be used as an under-glove indicator to evaluate the ingress of toluene through disposable gloves in a controlled environment, and compared these results to the amount of toluene ingress determined from the standardized test methods for determining chemical permeation through PPE. In a test chamber, with plugs for air sampling, five to six ACC patches were placed on a mannequin hand underneath disposable gloves (latex, nitrile, neoprene, polymer laminate). Three work-exposure scenarios were simulated to assess toluene ingress through the different gloves: vapor exposure; spray exposure, and immersion. The standard permeation test, using a diffusion cell, was carried with glove material of the palm, with continuous contact conditions. In all of ACC test, the order of toluene ingress was latex > neoprene > nitrile > Barrier, but for the standardized testing, the order of the neoprene and nitrile was reversed, and nitrile had higher levels of toluene ingress. These results show the need to think beyond standard testing techniques for occupational exposure to hazardous substances, and the added value of "application style" testing.

Enhancing performance evaluation and microbial community analysis of the biofilter for toluene removal by adding polyethylene glycol-600 into the nutrient solution

Polyethylene glycol-600 (PEG-600), as a carrier for slow release of organic substances, can improve the biocompatibility of packing fillers and the construction of biofilms. The gradient experiments were established to evaluate the feasibility of adding different content of PEG-600 to the biofilter for enhancing toluene removal. In particular, the evolution trend of microbial community embedded in packing fillers was measured by 16S rRNA-based gene sequencing. Results showed that the toluene removal efficiency of biofilter with 7.5% adding content of the PEG-600 was greatly improved, and the maximum elimination capacity of 152 g/(m³·h) was obtained. The introduction of PEG-600 enhanced the tolerance ability to withstand the transient impact loading and intensified the production of extracellular polymeric substances and bonding strength of biofilms. It should be noted that the abundance of Pseudomonas and Steroidobacter at genus level increased significantly. The microbial community evolved into a co-degradation system of toluene and PEG-600.

Simulating alveoli-inspired air pockets in a ZnO/NiMoO4/C3N4 catalyst filter for toluene entrapment and photodecomposition

Here, we propose an alveoli-inspired catalyst to address the susceptibility of photocatalytic air oxidation systems to fluctuations in volatile organic contaminant (VOC) loads. An alveoli structure was fabricated by covering ZnO nanorods grown on a stainless-steel mesh (SSM) with a porous NiMoO₄/C₃N₄ layer. The alveoli catalyst regulates VOC mass transfer from the air to the catalyst surface using air pockets that capture VOC molecules by diffusion driven by a concentration gradient. Air pockets act as localized reservoirs of molecules that prevent scarcity and congestion at the catalyst surface at low and high VOC loads, respectively. The presence of air pockets in the catalyst assembly and its potential to capture VOC was confirmed by a distinct bimodal adsorption configuration. A ZnO/NiMoO₄/C₃N₄@SSM (ZNC@SSM) catalyst with air pockets achieved a high degree of toluene adsorption (6.1 μmol·m^-2). Toluene selectivity of ZnO controlled the delivery of molecules to active catalyst sites, resulting in 95% toluene conversion in 90 min. Synergetic toluene adsorption in air pockets and degradation on catalytic sites helped achieve a quantum yield of 4.14 × 10^-05 molecules/photon. A figure of merit reflecting fundamental system parameters was compared with previous photocatalytic systems to evaluate the practicality of ZNC@SSM.