Ppm Toluene Research Articles

Nanosheet-state cobalt-manganese oxide with multifarious active regions derived from oxidation-etching of metal organic framework precursor for catalytic combustion of toluene

For the first time, a nanosheet-state CoMnx mixed oxide with multifarious active regions was synthesized by oxidation-etching assembly of metal organic framework (MOF) precursor and applied for catalytic combustion of toluene at low temperatures. The obtained optimum catalyst denoted as CoMn6 showed excellent performance, which achieved 90% conversion of 1,000 ppm toluene under a weight hourly space velocity (WHSV) of 60,000 mL/(g·h) at 219 °C. While, it also exhibited long-term stability with strong water resistance property. The characterizations of physicochemical properties indicated that the oxidation-etching assembly process built an abundant mesoporous structure in the CoMnx catalyst, which greatly increased the specific surface area (SSA). Especially, potassium permanganate as oxidant and manganese source led to uniform dispersion and assembling of cobalt atoms, which caused the generation of low-crystallinity CoMnx mixed oxide with abundant dislocations, vacancies, phase interfaces and amorphous structures, resulting in excellent low-temperature reducibility, outstanding lattice oxygen mobility and abundant active species such as Mn3+, Co3+ and adsorbed oxygen species. Density functional theory (DFT) calculations demonstrated that gaseous oxygen with the longer bond length (1.406 Å) and stronger adsorption energy (−4.443 eV) could be adsorbed and activated well on the MnCo2O4.5 (311) plane, which is beneficial for the toluene oxidation. In situ diffuse reflectance infrared spectroscopy (DRIFTS) technique was applied to track the intermediates of toluene combustion under different atmospheres, which further deduced the contributions of different active regions and oxidation mechanism over the CoMnx catalyst. The present facile strategy of oxidation-etching assembly of the MOF precursor for the creating of novel catalyst with high performance could be applied in a wide variety of materials besides VOC combustion catalysts.

Influence of Nickel Doping on Ultrahigh Toluene Sensing Performance of Core-Shell ZnO Microsphere Gas Sensor

As a volatile organic compound, toluene is extremely harmful to the environment and human health. In this work, through a simple one-step solvothermal method, Ni-doped ZnO sensitive materials (0.5, 1, and 2 at% Ni-doped ZnO) with a core-shell morphology were synthesized for the first time for toluene gas detection. The sensing test results showed that the sensor based on 1 at% Ni-doped ZnO exhibited the best toluene sensing performance. The response was up to 210 to 100 ppm toluene at 325 °C. The sensor exhibited high selectivity, fast response/recovery characteristics (2/77 s), and low detection limit (500 ppb, 3.5). Furthermore, we carried out molecular-level research on the sensitive material prepared in this experiment by various characterization methods. The SEM characterization results showed that ZnO and Ni-doped ZnO possessed the core-shell morphology, and the average grain size decreased with the increase in the Ni doping content. The UV–Vis test showed that the band gap of ZnO became smaller with the increase in the Ni doping amount. The enhanced toluene sensing performance of 1 at% Ni-doped ZnO could be ascribed to the structural sensitization and Ni doping sensitization, which are discussed in detail in the sensing mechanism section.

Nanocasting synthesis and highly-improved toluene gas-sensing performance of Co3O4 nanowires with high-valence Sn-doping

Co 3 O 4 nanowires (NWs) arrays with the different valence metal-cations-doping (Zn, In and Sn) were synthesized by nanocasting method. The cations-doping hardly affects the morphology and mesoporous-structures, and all samples in bundles are composed of nanowires with the same diameter. Mesoporous-structures of all cations-doped Co 3 O 4 NWs results in a higher response to toluene gas. The different valence metal-cations-doping greatly affects the gas-sensing performance of Co 3 O 4 NWs sensors, which the response increases with the metal valence. Co 2.841 Sn 0.106 O 4 NWs sensor possesses the highest response (7.28) to 100 ppm toluene gas for the highest surface area and high-valence Sn-doping. Mesoporous-structure absorbs more oxygen to form O - and the thicker hole accumulation lay in air, while Sn-doping supplies electrons to combine holes in E V and increases the resistance in toluene gas. The high response is dominated with mesoporous-structures of all Co 3 O 4 NWs, while the gas-sensing performance could be further improved with Sn-doping.

Effects of Co-Addition of Au and CuO to Macroporous SnO2 Microspheres on Their Acetone and Toluene Sensing Properties As Thick Film Sensors

Controlling of meso- and macro-porous structure of semiconductor metal oxide particles used as sensor materials is of primary importance in improving their gas response properties. To date, we could improve H2 and NO2 response properties of SnO2 [1] and In2O3 [2] thick film sensors by the introduction of macropores into these oxide particles, by employing ultrasonic spray pyrolysis (USP) of the oxide precursor solution containing polymethylmethacrylate (PMMA) microspheres as a template. We also demonstrated the usefulness of the Au loading on macroporous In2O3 (pr-In2O3) and the PdOx-CuOx loading on pr-WO3 in improving NO2 [3] and methylmercaptan [4] response properties, respectively.By the way, toluene and acetone are typical organic solvents used widely in many fields, but are very toxic and hazardous gases to be detected and then eliminated by suitable methods form the viewpoint of our safe and reliable life. In addition, the patients suffering from lung cancer and diabetes are known to release high concentrations of toluene and acetone, respectively. Therefore, the development of gas sensors capable of detecting these gases sensitively and selectively may offer a new and non-invasive diagnostic method of these diseases.In the present study, attempts were made to improve acetone and toluene response properties of thick film sensors fabricated by pr-SnO2 microspheres prepared by the USP method. Effects of the CuO addition to pr-SnO2 microspheres (pr-(CuO-SnO2)) and the additive methods of different amounts of Au to pr-(CuO-SnO2) microspheres on their response properties to both two gases have been examined.The aqueous solution containing 5.0×10-3 mol of SnCl4･5H2O and 3.2 g of PMMA microspheres (ca. 70 nm in size) per 100 mL of deionized water was used as the base precursor solution. The precursor mists were carried into the electronic furnace heated at 1,100°C to prepare pr-SnO2 microspheres. In preparing pr-(xCuO-SnO2) and pr-(yAu-xCuO-SnO2) (x and y: the additive amounts in wt% per the SnO2 weight), appropriate amounts of CuCl2･2H2O and HAuCl4･4H2O were added to the base precursor solution. Besides, an appropriate amount of Au was loaded on pr-(xCuO-SnO2) by a conventional impregnation method. Thick film sensors (10 - 15 mm in thick) were fabricated by screen printing of the slurry of thus-prepared pr-SnO2-based microspheres on an alumina substrate equipped with a pair of Pt electrodes, and their sensing properties to 20–100 ppm acetone, toluene and ethanol were measured in the temperature range of 300–500°C in air. The gas response is defined as the ratio of the sensor resistance value in air (Ra) to that in a sample gas (Rg). The sensors thus fabricated are referred to as the abbreviations of sensor materials.Figure 1 shows FE-SEM photographs of pr-SnO2-based microspheres prepared. All kinds of microspheres are confirmed to show similar porous structure formed by the thermal decomposition and evaporation of PMMA microspheres contained in the mists of the precursor solutions, except for 3.0Au/pr-(2.0CuO-SnO2). The appearance of 3.0Au/pr-(2.0CuO-SnO2) microspheres indicates partial filling of the loaded Au inside of the pores especially for the outermost surface of macroporous microspheres. Figure 2 shows variations in response to 100 ppm acetone of pr-SnO2-based sensors with operating temperature. The order of sensor resistance value in air was pr-(3.0Au-2.0CuO-SnO2) ³ pr-(2.0CuO-SnO2) > pr-(5.0Au-2.0CuO-SnO2) > 5.0Au/pr-(2.0CuO-SnO2) > 3.0Au/pr-(2.0CuO-SnO2) > pr-SnO2 at 350°C. Although the physicochemical states of Au and CuO in pr-(5.0Au-2.0CuO-SnO2) are not clarified yet, the addition of CuO to pr-SnO2 resulted in an increase in sensor resistance in air, due to the formation of p-n heterojunction in the macroporous microspheres. In contrast, the Au addition to or the Au loading on pr-(2.0CuO-SnO2) led to a decrease in sensor resistance. Among the sensors tested, pr-(3.0Au-2.0CuO-SnO2) showed the largest response to 100 ppm acetone at 350°C. Therefore, high sensor resistance in air is one important factor for the largest acetone response, but the added Au in pr-(3.0Au-2.0CuO-SnO2) is considered to accelerate the reaction of acetone with chemisorbed oxygen effectively. The smaller acetone response observed with 3.0Au/pr-(2.0CuO-SnO2) is considered to arise from the decrease in reaction site, as is confirmed by Fig. 1 d). The detailed gas response properties of these sensors, including those to toluene and ethanol, the latter is a possible interference gas in detecting acetone and toluene, will be reported in the presentation.[1] K. Hieda, et al., Sens. Actuators B, 133(1), 144-150 (2008).[2] T. Hyodo, et al., Sens. Actuators B, 187, 495-502 (2013).[3] T. Ueda, et al., Front. Mater., 6, 1-10 (2019).[4] N. Tammanoon, et al., ACS Appl. Mater. Interfaces, 2020, 12, 41728-41739 (2020). Figure 1

Insight into the promotional effect of NO2 on toluene oxidation over MnCe/HZSM-5 catalyst

A thorough probe into the activation mechanism of NO2 on toluene oxidation during co-removal of toluene in NH3-SCR unit is imperative but still lacking. This study unraveled the promotional effects of NO2 on toluene conversion, CO2 selectivity and catalytic stability over a MnCe/HZSM-5 catalyst. 1000 ppm NO2 was sufficient for complete oxidation of 50 ppm toluene into CO2 at 280 °C in the absence of O2 (C7H8 + 18NO2 → 7CO2 + 4H2O + 18NO). NO2 had stronger oxidizing ability than O2, while O2 re-oxidized NO to NO2, resulting in a synergistic contribution to toluene conversion. NO2 participated in toluene oxidation producing predominant NO and negligible organic N-byproducts. The N in NO2 scarcely took part in the organic synthesis process. NO2 gave one of its O easily to provide additional Osur and improved mobility and activity of Olat, hence speeding up the re-oxidation of reduced metal sites. The activation of NO2 on toluene oxidation predominantly followed Mars-van Krevelen mechanism. The Langmuir-Hinshelwood mechanism also existed but was less important.

Efficient Degradation of Toluene over Ce a Mn β O X ‐X Synthesized by One‐Step Strategy

Toluene was converted to CO2 and H2O after a short contact with the catalyst in a fixed bed reactor. The results of catalyst activity evaluation were in accordance with the sequence of CeMnOx-10.5 (T100%=215 °C)>CeMnOx-8 (T100%=220 °C)>CeMn2Ox-10.5 (T100%=225 °C)>Ce3MnOx-10.5 (T100%=235 °C)>CeMnOx-6 (T100%=245 °C).

AuPd nanoparticles functionalized core–shell Co3O4/ZnO@ZnO for ultra-sensitive toluene detection

In this work, core–shell AuPd nanoparticles (NPs) sensitized Co3O4/ZnO@ZnO ellipsoid nanoparticles was successfully synthesized via a simple liquid phase synthesis method. SEM and TEM characterization results showed that the as-prepared samples have core–shell ellipsoid morphology and the size of the nanoparticles were uniform. Systematic gas sensing characterization was carried out to obtain the gas sensing property of AuPd NPs decorated Co3O4/ZnO@ZnO. It was found that the gas sensing property could be significantly enhanced after noble metal decoration with Au, Pd and AuPd NPs, respectively. The optimal gas sensing performance was achieved by AuPd NPs functionalized Co3O4/ZnO@ZnO based gas sensor. The maximum response reached 256–100 ppm toluene at 250 °C, which is 50 °C lower than pure ZnO. The detection limit of AuPd functionalized Co3O4/ZnO@ZnO was as low as 100 ppb. The enhanced sensing mechanism was mainly attributed to the synergistic effect of Au and Pd, which was detailly discussed in gas sensing mechanism part.

Boosting toluene oxidation by the regulation of Pd species on UiO-66: Synergistic effect of Pd species

Supported single-atoms and sub-nanometre clusters have exhibited superb catalytic performance toward many reactions. However, inactivation of single-atom or cluster catalysts in complex reactive conditions poses major challenge for their practical application. Herein, we demonstrate that the prepared Pd-UiO-66 with ultra-low Pd loading (0.05 wt%) contains three robust active Pd species, (isolated Pd atom (Pd1), sub-nanometre Pd clusters (Pdc) and Pd nanoparticles (Pdn)) and presents superb activity for toluene oxidation and water resistance (10.0 vol%). Experiments and theoretical calculations firstly confirm that consecutive H2-O2 and reaction gas treatment (1000 ppm toluene in 20 vol.%O2/Ar) induce residual N species from solvent N, N-dimethylformamide to enter UiO-66 skeleton forming Pd1-N1 structures. DFT calculations reveal that the synergistic effect of Pd species (namely, the enhanced activation of O2 and H2O by Pd1 and the improved adsorption of toluene by Pdc and Pdn) is the main factor for the excellent activity of Pd-U-H-O-reused catalyst.

Removal of gaseous toluene by nonthermal plasma coupled with wet scrubber containing Fe2+

A non-thermal plasma with a wet scrubber (NTP + WS) was used to degrade gaseous toluene. Compared with the NTP + WS/H2O system, the toluene and by-product ozone removal efficiencies were increased by 10% and 85% in the NTP + WS/Fe2+ system, respectively. For 60 ppm toluene degradation, the maximum mineralization rate (MR) of toluene (61%) was obtained, at the optimum Fe2+ concentration of 50 mg/L. During catalytic oxidation, the removal efficiency of toluene was limited by its solubility in WS systems. In addition, decreased Fe2+ concentration and accumulation of organics led to the system deactivation. The EPR and quenching experiments verified the presence and contribution of hydroxyl radicals (4.6%) and superoxide radicals (3.8%) to the removal efficiency of toluene. Based on the radicals and intermediates detected in the gas and liquid phases, a degradation mechanism for toluene in the NTP + WS/Fe2+ system was proposed.

Part per trillion level DMMP gas sensor based on calixarene modified organic thin film transistor

Dimethyl methylphosphonate (DMMP) is a simulant of nerve agent sarin, which still remains a great challenge to detect due to lack of sensitive, selective and stable sensor. In this work, calixarenes are designed to apply on organic thin film transistor (OTFT) to form a high-performance gas sensor for DMMP detection. The theoretical calculation indicates that the binding energy between calixarene (4-tert-Butylcalix[6]arene, denote as TB6) and DMMP is stronger (–25.34 kcal/mol) than that of poly(3-hexylthiophene-2,5-diyl) (semiconductor layer of this OTFT sensor, denote as P3HT) (–10.83 kcal/mol), which could bring significant improvement to the sensitivity of this sensor. The experimental result confirms that the limit of detection (LOD) of TB6-P3HT based sensor can be as high as 10 ppt which is about four orders of magnitude higher than pristine P3HT. The drain current changes after exposure to 50 ppm DMMP, ethyl acetate, toluene, isopropanol and nitrogen dioxide are 39.0%, 2.9%, 2.7%, 2.1% and 1.3%, which also suggests the good selectivity of this sensor. Besides, the TB6-P3HT based sensor exhibits a better stability (14.1% degradation after one month) than pristine P3HT (55.8%) because of the better antioxidant capacity of this bilayer structure. Further, this sensor shows its ability to work in different relative humidity and temperatures, which demonstrates the potential application in complex environment. We anticipate this general approach could offer solutions for high performance gas detection.

Improved Toluene Response of Mixed-Potential Type YSZ-Based Gas Sensors Using CeO2-Added Au Electrodes

YSZ-based potentiometric sensors employing thin CeO2-added Au sensing electrodes (SEs) were fabricated by using a spin-coating method, and effects of the CeO2 addition on their toluene sensing properties were examined. The sensor response (ΔE) to 50 ppm toluene of the sensors using 8 wt% CeO2-added Au SEs tended to decrease with an increase in the number of spin-coating cycles (x: 5, 10, 15; i.e., the thickness of SEs). However, ΔE of the sensors using 24 wt% CeO2-added Au SEs showed an opposite behavior to what was observed for 8 wt% CeO2-added Au SEs. The sensor using the thickest SE (x: 15) showed the largest ΔE (e.g., ca. 212 mV for 50 ppm toluene) at 450 °C among all the sensors examined and responded even to 0.5 ppm toluene. ΔE exponentially increased with an increase in logarithmic toluene concentration in the range higher than 10 ppm. These obtained results indicate that electrochemical toluene oxidation proceeds at triple-phase boundaries in SE with gas (Au/CeO2/gas) in addition to conventional TPBs (SE/YSZ/gas) in addition to the conventional interface at SE/YSZ/gas, because CeO2 is a mixed ionic and electronic conductor. The electrochemical reactions at TPBs of the sensor were also discussed on the basis of the I–E characteristics and the electrochemical impedance properties.

Activation or passivation: Influence of halogen dopant (F, Cl, Br) on photothermal activity of Mn2O3 in degrading toluene

Mn2O3 is an exceptional earth-abundant mineral that has been extensively applied in catalytic oxidation because of the strong redox couples like Mn3+/Mn2+ and Mn4+/Mn3+ exposed on Mn2O3 surface. Herein, the catalytic activity of Mn2O3 in photothermal degradation of toluene was regulated by halogens including F-, Cl-, and Br-. As the electronegativity ordered in F (3.98) > O (3.44) > Cl (3.16) > Br (2.96), F- doped Mn2O3 overperforms Cl- doped and Br- doped Mn2O3 in decomposing toluene. DFT theoretical calculation illustrates that F- attracts the shared electrons from Mn to itself, the deviated charge center stretches the adjacent Mn-O bonds and boosts the generation of abundant oxygen vacancies, helping to strengthen the catalytic activity of Mn2O3. Conversely, Mn-O bonds are shortened by Cl- and Br- that have lower electronegativity than O. The multiple electrons circling Cl- and Br- push Mn towards O and squeeze Mn-O bonds, resulting in the formation of passivated Mn2O3. In conjunction with Mn redox couples and oxygen vacancies, 99% of 400 ppm toluene can be eliminated by F- doped Mn2O3, corresponding mineralization rate is high up to 95.8%.

Construction of hollow NiO/ZnO p-n heterostructure for ultrahigh performance toluene gas sensor

In this work, NiO/ZnO hollow microspheres were successfully fabricated by a simple co-precipitation method. The structural and morphological properties of NiO/ZnO composites were studied by various characterization methods. Gas sensing results revealed that the sensor of NZ-2 and the working temperature was 300 °C showed highest response value (S = 240) and good selectivity to 100 ppm toluene. Compared with pure ZnO hollow microspheres, the sensitivity of NiO/ZnO hollow microspheres is significantly improved by about 20 times. The response/recovery time were 2/33 s respectively at the same time, the detection limit can be reduced to ppb level. The possible mechanism for improvement of gas sensing performance is detailly analyzed, which is mainly due to the unique hierarchical microstructure and the composition of p-n heterojunction at the contact surface between p-type NiO and n-type ZnO structures as well as the catalytic effect of NiO.

Performance of octadecylamine-functionalized graphene oxide nanosheets in polydimethylsiloxane mixed matrix membranes for removal of toluene from water by pervaporation

Functionalized and reduced graphene oxide nanosheets with octadecylamine (rGOODA) were incorporated in polydimethylsiloxane (PDMS) membranes to be used in pervaporation for removal of toluene from water. The properties of the functionalized nanosheets were characterized by FTIR, XRD, Raman, SEM, and TGA analyses. The prepared mixed matrix membranes (MMMs) were characterized using contact angle, AFM, SEM-EDX, TGA, solvent uptake tests. The membranes contained reduced graphene oxide (rGO) represented 111% increment in the enrichment factor compared to that of the bare-PDMS owing to Π-Π interaction of graphene nanosheets and the toluene's aromatic ring as well as high aspect ratio of rGO that causes more tortuous pathways for water permeation. By incorporating rGOODA in the MMMs, the separation factor was increased about 164% rather than that of rGO-contained membrane, which could be mainly attributed to closer Hansen solubility parameter of the functionalized nanosheets to that of toluene, water repelling of the membrane due to more hydrophobicity and steric hindrance of the functionalized nanosheets, their well dispersion which causes more compatibility with the polymeric matrix. The pervaporative performance of membranes with different filler contents were investigated as a function of operational temperatures and feed concentrations. The prepared MMM with 0.4 wt% rGOODA presented the best performance at 30 °C and 150 ppm toluene concentration.

Light-Excited Ag-Doped TiO2−CoFe2O4 Heterojunction Applied to Toluene Gas Detection

(1) Background: Toluene gas is widely used in indoor decoration and industrial production, and it not only pollutes the environment but also poses serious health risks. (2) Methods: In this work, TiO2−CoFe2O4−Ag quaternary composite gas-sensing material was prepared using a hydrothermal method to detect toluene. (3) Results: The recombination of electron–hole pairs was suppressed, and the light absorption range was expanded after constructing a heterojunction and doping with Ag, according to ultraviolet–visible (UV–vis) diffuse reflectance spectra and photoluminescence spectroscopy. Moreover, in the detection range of toluene gas (3 ppm–50 ppm), the response value of TiO2−CoFe2O4−Ag increased from 2 to 15, which was much higher than that of TiO2−Ag (1.7) and CoFe2O4−Ag (1.7). In addition, the working temperature was reduced from 360 °C to 263 °C. Furthermore, its response/recovery time was 40 s/51 s, its limit of detection was as low as 10 ppb, and its response value to toluene gas was 3–7 times greater than that of other interfering gases under the same test conditions. In addition, the response value to 5 ppm toluene was increased from 3 to 5.5 with the UV wavelength of 395 nm–405 nm. (4) Conclusions: This is primarily due to charge flow caused by heterojunction construction, as well as metal sensitization and chemical sensitization of novel metal doping. This work is a good starting point for improving gas-sensing capabilities for the detection of toluene gas.

Porous Mn-doped Co3O4 nanosheets: Gas sensing performance and interfacial mechanism investigation with In situ DRIFTS

Unraveling the gas-solid interfacial sensing mechanism during gas sensing is very essential for the development of high-performance gas sensors. In this work, the Mn-doped Co3O4 porous nanosheets with 5.6 times higher response than pristine Co3O4 and short response/recovery time (55/30 s) for 100 ppm toluene gas is synthesized. More importantly, in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) is conducted to investigate the gas-solid interfacial sensing mechanism over 3-Mn-Co3O4. The interfacial reaction species have been monitored, such as methylbenzene, benzyl alcohol, benzaldehyde, benzoic acid, carbon monoxide, and water molecule. These species originate from the elementary and overall reactions during toluene gas sensing. The dynamic evolution of surface species could be divided into three stages of adsorption reaction, reaction balance, and desorption reaction. Furthermore, combined with the density function theory simulation calculation, the gas-solid interfacial sensing mechanism over 3-Mn-Co3O4 is proposed. Toluene molecule reacts with the surface active oxygen species resulting in the occurrence of a series of elementary reactions and the generation of intermediates. The products of overall reaction are CO2 and H2O during gas sensing. Our work implements a meaningful exploration of in situ DRIFTS in gas-sensing field and provides a distinctive view to understand the gas-soild interfacial gas-sensing mechanism.

Co-exposure to Toluene and Noise Made Synergistic and Antagonistic Effects on Some Neurotoxic Parameters in New Zealand White Rabbits.

Numerous physical and chemical agents can induce destructive effects on the brain tissue. Noise and toluene, which are some of these harmful agents, have significant adverse effects on the brain tissue. This work aimed to investigate the neurotoxic changes induced by co-exposure to toluene and noise. A total of 24 male white New Zealand rabbits were randomly segregated into four groups, including toluene exposure, noise exposure, co-exposure to noise and toluene, and control. This in vivo study tested the neurotoxic effects of exposure to 1000 ppm toluene and 100 dB noise during two weeks (8 h/day). The serum levels of brain-derived neurotrophic factor-α (BDNF-α), malondialdehyde (MDA), glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase and total antioxidant capacity (TAC) values in the brain tissue were measured. Moreover, hematoxylin and eosin (H&E) staining was utilized for brain pathological analysis. Exposure to noise increased TAC values in the cerebral cortex. Co-exposure to toluene and noise increased the serum levels of BDNF-α. Nevertheless, exposure to noise decreased the levels of BDNF-α in serum. On the other hand, histopathological examinations using H&E staining exhibited that different signs of inflammation, such as lymphocyte infiltration, pyknosis, vacuolization, and chromatolysis were induced by exposure to noise and toluene in the cerebellum, hippocampus, and frontal section in the brain tissue. In addition, simultaneous exposure to toluene and noise induced antagonistic and synergistic changes in some neurotoxic parameters. Exposure to noise and toluene, which caused inflammation in the brain tissue cells, could be a noticeable risk factor for the neurological system. Exposure to noise increased total antioxidant capacity.Exposure to toluene decreased brain-derived neurotrophic factor-α.Exposure to noise decreased brain-derived neurotrophic factor-α.Co-exposure to noise and toluene increased brain-derived neurotrophic factor-α.Noise and toluene induced some histopathological effects on the brain tissue. The brain tissue can be adversely affected by various agents, including noise and toluene. This study aimed to examine the effects of simultaneous exposure to noise and toluene on the nervous system. Twenty-four healthy male white New Zealand rabbits were randomly divided into four groups: control, noise, toluene, and simultaneous exposure to noise and toluene. The study involved a two-week in-vivo experiment, subjecting the rabbits to 100 dB noise and 1000 ppm toluene for eight hours per day. This study showed that exposure to noise and toluene changed different parameters relating to the neurological system. Furthermore, noise and toluene induced some adverse effects on the brain tissue. This study suggested that exposure to noise and toluene can lead to harmful effects on the brain tissue, posing a significant risk to the neurological system.

Impact of toluene contamination on the oxygen reduction at polycrystalline platinum electrode: Poisoning and mitigation

Cyclic and hydrodynamic voltammetric measurements have been used to examine mechanistically the oxygen reduction reaction (ORR) at toluene-poisoned polycrystalline platinum (poly-Pt) electrode to explore the effect of poisoning with toluene, as a hydrocarbon model, on the electrochemical behavior of ORR at poly-Pt electrode. For this purpose, ORR is used as a marker reaction for the poisoning extent and for the ease of the in-situ mitigation of the poly-Pt electrode activity. The in-situ recovery at various scenarios is examined as it is crucial for the development of proton-exchange membrane fuel cells (PEMFs). Rotating ring-disk electrode voltammetry proved that the toluene-poisoning of poly-Pt electrode results in the change in ORR mechanism from the direct reduction of O2 to H2O to the reduction of O2 to H2O2 followed by further reduction to H2O. Voltammetric studies shows a preferential adsorption of toluene on the various facets of poly-Pt electrode. Recovery scenario in which the potential of the electrode was scanned in the range −0.2 to 1.3 V was found to be remedial in complete recovery of the poisoned electrode. Using RRDE, it has been shown that the limiting current in 100 ppm toluene contaminated H2SO4 at the previously reduced and oxidized electrodes to decrease to 60% and 20% of the value obtained in the absence of toluene.

Self-assembled Co3O4@WO3 hollow microspheres with oxygen vacancy defects for fast and selective detection of toluene

As the demand for detecting harmful gases becomes more and more urgent, a potential gas-sensing material with high response and good selectivity based on Co3O4-functionalized WO3 hollow microspheres was successfully synthesized in this study. A variety of techniques were employed to analyze the chemical and structural properties of the samples, involving X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive Spectrometer (EDS) and X-ray Photoelectron Spectroscopy (XPS). The gas-sensing properties of WO3, Co3O4 and Co3O4-functionalized WO3 hollow spheres towards toluene were investigated to determine the effects of functionalization. In comparison with pure WO3 hollow microspheres, the sensing properties of the complex modified by Co3O4 nanoparticles to toluene were significantly enhanced. The response value of the composite to 100 ppm toluene could reach 55.8, which was nearly three times higher than that of pure WO3 hollow microspheres. The enhancement of gas sensitivity could be mainly attributed to the catalytic activity of Co3O4 in the process of toluene oxidation, the increase in chemisorbed oxygen species and oxygen vacancies, and the widening in conductive channel as a result of the existence of Co3O4 nanoparticles in the Co3O4-functionalized WO3 composite.

An ultra-sensitive room temperature toluene sensor based on molten-salts modified carbon nitride

In this work, two-dimensional crystalline C3N4 (CCN) was obtained by promoting the self-condensation reaction of dicyandiamide in an air atmosphere via the molten salt method. Studies show that compared with polymer-C3N4 (PCN) ((9.8 m2/g)), CCN has a larger specific surface area (77.1 m2/g)) and better crystallinity. Additionally, the resistance of CCN in the air is 40 MΩ, 1250 times lower than that of polymer-C3N4 (PCN) (∼50000 MΩ). Secondly, when 50 ppm toluene gas analysis flows into the CCN based gas sensor at room temperature, the gas response value is 350. The CCN based gas sensor works for 60 days, or after 25 cycles continuously, the gas response value remains at about 350 (Rg/Ra), which is due to the excellent crystallinity, optimized π conjugate system, and enhanced interlayer van der Waals of CCN. Additionally, the critical effect of crystallinity on the gas sensitivity of carbon nitride is also discussed in detail.