Benzene Vapor Research Articles

To the adsorbent obtained on the basis of local Angren coal analysis of adsorption energy properties of benzene vapors

This article provides information on ensuring safety at coal mines by analyzing existing coal mining facilities. Information on the Angren coal mine is also given. It is shown that there are no accurate methods for determining the location of fires in order to increase the efficiency of spontaneous combustion prevention by supplying liquid compositions such as water and clay pulp flowing down the formation soil. Measures have been proposed to suppress spontaneous combustion centers, nitrogen is being increasingly used, the supply of which ensures volumetric processing of the collapsed mass and allows reducing the oxygen concentration in the mined-out space.

Reticular chemistry for the rational design of mechanically robust mesoporous merged-net metal-organic frameworks

Reticular chemistry for the rational design of mechanically robust mesoporous merged-net metal-organic frameworks

Investigation of oxygen-enriched atmosphere combustion of oily sludge: Performance, mechanism, emission of the S/N-containing compound, and residue characteristics

It is an indispensable and important link to increasing the harmless treatment of oily sludge at the end of the petrochemical production stage to achieve the goal of clean production. This paper comprehensively investigates the thermal transformation behavior and the release of gaseous pollutants (VOCs, NOx, and S-containing gas) of petrochemical oily sludge. The results show that Petroleum hydrocarbons composed of C6–C35 can be effectively removed in the temperature range of 241–607 °C. It is worth noting that since low boiling point components such as benzene and toluene in the oily sludge may volatilize rapidly near the initial combustion temperature and generate toxic and harmful gases. For example, in this study, the toluene vapor signal could be observed before the initial combustion temperature and the toluene vapor signal appeared neatly around 350 °C and did not participate in the combustion reaction and the strong fluctuation of benzene vapor. Organic sulfur dominated by Sulfonate-S, Sulfoxide-S, and Aromatic-S could be released in the form of SO2 around 250 °C and 450 °C, while organic nitrogen dominated by Pyridinic-N, Protein-N, and Pyrrolic-N could be released in the form of NOx between 300 °C and 500 °C, which is mainly related to the thermal stability of sulfur-containing groups.

Study of programmed co-precipitation of aluminum doped zinc oxide for high precision design of gas analytical units

Developed high precision protocols of synthesis and printing of materials doped at a level of a few atomic percent serve as a prerequisite to addressing the problem of discreteness of electronic noses, i.e. multisensor arrays. Reproducible composition and microstructure of functional materials are needed to ensure low sensor-to-sensor variation, while high precision printing techniques help to mitigate non-uniformity of the deposited layers, to further ensure orthogonality of signals of a sensor array, especially when realized on a single chip.In this study, we evaluate two precise methods, programmed co-precipitation and aerosol jet printing, for making x%Al:ZnO layers, where x = 0.5, 1.0, 1.5, 2.5, and 5.0% over SiO2/Si substrate. We examined the phase and microstructure of the obtained powders depending on the Al content and the synthesis conditions. The obtained powders were utilized to prepare dispersions used as functional inks for aerosol jet printing of oxide microstructures on multielectroded chips to explore their sensing performance.We demonstrated the high influence of both the Al:Zn atomic ratio, and the synthesis conditions on the microstructure of the prepared materials composed of nanoparticles, micro- and nanorods with distinct synthesis-dependent characteristics. All inks based on x%Al:ZnO enabled achieving narrow, down to 50 µm, resolution and printing homogeneous structures, whereas using 0.5 %Al:ZnO nanoparticles ensured the best characteristics of the printed layers.The sensors made of 0.5 %Al:ZnO printed layer demonstrated a high mean sensing response towards 1 ppm of acetone, ethanol, and benzene vapors mixed with air, i.e. 0.75 ± 0.02, 0.51 ± 0.03, and 0.25 ± 0.017 at 250 °C, respectively, and both low detection limit and low sensor-to-sensor variation.

Изучение процесса адсорбции паров бензола активированными углями марок АР-А, АР-Б и углями компании Baojun Activated Carbon

We presented the results of a study of the adsorption capacity of domestic activated carbon grades AR-A and AR-B, and a coal from Baojun Activated Carbon (China) with respect to benzene vapor. All used adsorbents are designed to purify air from vapors of volatile organic compounds, but differ in production technology and physicochemical characteristics. It has been established that the efficiency of Baojun Activated Carbon’s activated carbon in the adsorption of benzene vapor is higher than that of domestic samples of AR-A and AR-B grades. At the same time, among foreign-made coal, the most effective sample was Baojun 4.0/90, which has a high adsorption capacity, declared in relation to carbon tetrachloride vapor. It has been experimentally shown that in all cases the kinetics of the adsorption process is well described by the Ho and MacKay pseudo-second order equation. Similar results were obtained using the Morris --- Weber model, which takes into account the role of diffusion processes in the adsorption of benzene vapor by activated carbons. The use of the Lagergren equation and the simplified Elovich model for processing experimental data showed less significant results

Research and manufacture toxic gas filter materials on the basis of activated carbon impregnated with additives used in the manufacture of fire escape masks

This paper presents the results of research and fabrication of a layer of material that adsorbs some toxic gases that stimulate acidic respiration and the smoke and dust generated by the fire. Methods used: SEM- EDS; determining the BET surface area; the protection time with benzene and HCl vapor on the dynamic adsorption device DPC5... The results showed that the additively impregnated activated carbon cloth filter material has a specific surface area in BET of 697 m2 /g, has a protection time against benzene vapor of 34 minutes; protection time with HCl acid vapor is 33 minutes and the ability to filter smoke particles reached 94%. The filter material made from coconut shell activated carbon has a surface area calculated according to BET being 664 m2/g, has a protection time with benzene vapor (L= 5 cm, Co = 18 mg/L) of 56 minutes; protection time with HCl acid vapor (L= 5 cm, Co= 1.1 mg/L) is 280 minutes. Construction of Xylop curve determines the ability to filter benzene vapor and the ability to filter HCl acid vapor shows. This material has potential for the use in the manufacture of personal respiratory protection and environmental remediation.

Research and fabrication of toxic filter materials from Tra Bac coconut shell activated carbon applied in the manufacture of personal respiratory protection devices

This paper presents the results of research on making materials to adsorb toxic acidic gases, organic substances from Tra Bac coconut shell activated carbon, and combined with chemical treatment on the laboratory scale. Methods were used for this study consisting of SEM, EDS; BET, and DPC5 (kinetic adsorbent). The results showed that the fabricated filter material has a surface area of 664 m2/g, calculated according to BET, has a protection time with benzene vapor (L= 5 cm, Co(vapor) = 18 mg/L) of 56 minutes; protection time with HCl acid vapor (L= 5 cm, Co (vapor) = 1.1 mg/L) is 280 minutes. The results of the study have exhibited a good ability to filter benzene vapor and HCl vapor. This material has the potential for use in the manufacture of personal respiratory protective equipment.

High-efficiency removal of benzene vapor using activated carbon from Althaea officinalis L. biomass as a lignocellulosic precursor.

Benzene is a primary air pollutant commonly found widespread in the indoor environment. It has always been a research focus on the environment due to the causes of significant human health concerns. It has been widely utilized in the synthesis of solvent production, which can rarely be found in high concentrations in outdoor air or high amounts in indoor air, depending on its sources. It is aimed to remove different initial benzene concentrations (from 5 to 1500ppm) with the production of activated carbon as an excellent adsorbent with a high surface area to be used in these situations. Lignocellulosic wastes have great potential for activated carbon for their advantages (abundant, recycled, and low-cost materials, etc.). This study aimed to evaluate biowaste material for activated carbon production from Althaea officinalis L. biomass by chemical activation (H2SO4, LiOH, and ZnCl2) at temperatures between 500 and 900°C. Newly developed powdered activated carbons (Ao-ACs) are also tabulated as Ao-AC1-45 for easy reference. Benzene vapor was collected into Tenax TA® tubes by automatic thermal desorption in conjunction with a capillary gas chromatography-mass spectrometry (TD-GC/MS). The significant surface area and production yield of Ao-ACs were obtained at 1424 m2/g (Ao-AC43) and up to 40.32%, respectively. The maximum gas-phase benzene adsorption capacity was 140mg/g at 270min. This research has focused on adsorption gas-phase benzene removal onto Ao-ACs as a low-cost adsorbent from the Althaea officinalis L. biomass. Conspicuously, more study is needed to perform the enhanced adsorption of airborne pollutants capacity with inexpensive activated carbon from waste biomass materials.

Atomic layer deposited Pt/TiO2-SiO2 and Pt/ZrO2-SiO2 for sequential adsorption and oxidation of VOCs

In this work, Pt nanoparticles were loaded on SiO2, TiO2-thin-film-modified SiO2 (TiO2-SiO2), or ZrO2-thin-film-modified SiO2 (ZrO2-SiO2) particles and the composites were investigated for sequential adsorption and desorption/catalytic oxidation of benzene. The SiO2 was prepared via sol–gel method, while TiO2-SiO2 and ZrO2-SiO2 were synthesized via atomic layer deposition (ALD) thin film coating of TiO2 or ZrO2 on SiO2 particles substrate. In the sequential capture-reaction tests, the materials were first exposed to ca. 500 ppmv benzene gas at 25 °C and 1 atm until 5% breakthrough was attained, followed by tandem desorption and catalytic oxidation while raising bed temperature to 200 °C. The benzene vapor adsorption isotherms followed type-IV isotherm classification, revealing a combination of monolayer, multilayer and capillary condensation adsorption mechanisms in sequence. The xPt/ZrO2-SiO2 materials exhibited superior capture-conversion capabilities relative to their xPt/TiO2-SiO2. In particular, 3Pt/ZrO2-SiO2, prepared with 3 cycles of Pt ALD, exhibited the maximum in-situ conversion at ∼ 100% and turnover frequency of 17.1 mmolC6H6/molPt/s with a dynamic adsorption capacity of 0.45 mmol/g, indicating synergistic effects of Pt nanoparticles and ZrO2 in the ALD-based dual-function materials.

Multipass Raman gas analyzer for monitoring of atmospheric air composition

An improved gas analyzer based on Raman spectroscopy is presented. The device can measure the content of all molecular species of atmospheric air, whose concentration exceeds the sensitivity threshold. To obtain a high signal-to-noise ratio, a multi-pass optical system for scattering excitation was used together with the compression of the analyzed gas sample to a pressure of 20 atm. A technique for deriving concentrations from Raman spectra of atmospheric air based on the contour fit method is described. At the working pressure, a good agreement between the measurements of the daily air concentration of the carbon dioxide (CO2) and methane (CH4), and the data obtained with a high-sensitive CRDS gas analyzer was obtained. The standard deviation of the measured CH4 concentration values was ∼ 20 ppb. Estimates are given for the detection limits of the most common gas impurities in air, as well as for the Raman scattering cross sections for formaldehyde (CH2O), benzene (C6H6), and toluene (C7H8) vapor.

Rational design of imine‐linked three‐dimensional mesoporous covalent organic frameworks with bor topology

AbstractThree‐dimensional (3D) covalent organic frameworks (COFs) possess great potential applications in various fields. Constructing 3D COFs with large pore sizes is extremely challenging due to the interpenetration and collapse. Herein, we report a series of crystalline imine‐linked 3D COFs (3D‐bor‐COF‐1, 3D‐bor‐COF‐2, 3D‐bor‐COF‐3) with mesoporous channels through rationally designing the topology configuration. These 3D‐bor‐COFs display permanent porosity and Brunauer–Emmett–Teller (BET) surfaces of 3205.5, 1752.7, and 2077.3 m2 g−1 (SLangmuir = 4277.7, 2480.3, and 2698.0 m2 g−1), respectively. The pore sizes of 3D‐bor‐COFs were confirmed by the lattice fringes from high‐resolution transmission electron microscopy, as well as structural simulation and nitrogen adsorption isotherm analysis. 3D‐bor‐COFs display large pore sizes (3.8 nm for 3D‐bor‐COF‐3), which is among the highest record of 3D COFs. Owing to the unstacked‐aromatic pore environment and high specific surface area, 3D‐bor‐COFs display excellent adsorption capacity for benzene vapor (1203.9 mg g−1 for 3D‐bor‐COF‐3) under 298 K, which is three times higher than that of the best‐reported 2D COF. This work not only provides inspiration for designing 3D mesoporous imine‐COFs, but also demonstrates a strategy for constructing aromatics adsorption materials.

Screen-Printing of Functionalized MWCNT-PEDOT:PSS Based Solutions on Bendable Substrate for Ammonia Gas Sensing.

Multi-walled carbon nanotubes (MWCNTs) were grown on a stainless-steel foil by thermal chemical vapor deposition (CVD) process. The MWCNTs were functionalized with carboxylic groups (COOH) on their surfaces by using oxidation and acid (3:1 H2SO4/HNO3) treatments for improving the solubility property of them in the solvent. The functionalized MWCNTs (f-MWCNTs) were conducted to prepare the solution by continuous stir in poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), dimethyl sulfoxide (DMSO), ethylene glycol (EG) and Triton X-100. The solution was deposited onto a bendable substrate such as polyethylene terephthalate (PET) with a fabricated silver interdigitated electrode for application in a room-temperature gas sensor. A homemade-doctor blade coater, an UNO R3 Arduino board and a L298N motor driver are presented as a suitable system for screen printing the solution onto the gas-sensing substrates. The different contents of f-MWCNTs embedded in PEDOT:PSS were compared in the gas response to ammonia (NH3), ethanol (C2H5OH), benzene (C6H6), and acetone (C3H6O) vapors. The results demonstrate that the 3.0% v/v of f-MWCNT solution dissolved in 87.8% v/v of PEDOT:PSS, 5.4% v/v of DMSO, 3.6% v/v of EG and 0.2% v/v of Triton X-100 shows the highest response to 80 ppm NH3. Finally, the reduction in the NH3 response under heavy substrate-bending is also discussed.

Dynamic adsorption behavior of benzene, toluene, and xylene VOCs in single- and multi-component systems by activated carbon derived from defatted black cumin (Nigella sativa L.) biowaste

In the current study, activated carbon (AC) was produced from defatted black cumin (Nigella sativa L.) biowaste (DBCB) with ZnCl2 activation by means of the response surface methodology. The optimum process conditions for the production of DBCB-AC with a high iodine number of 1055.02 mg/g were predicted as an activation time of 57 min, activation temperature of 550 °C, and impregnation ratio of 105%. The surface and textural properties of the optimal DBCB-AC were characterized by SEM, FTIR, and BET analysis techniques. The DBCB-AC exhibited a highly porous structure with a specific surface area of 1213.32 m2/g, total pore volume of 0.89 cm3/g, and micropore surface area of 787.65 m2/g. Exploring the comparative and competitive adsorption behavior of volatile organic compounds (VOCs) is of both practical and scientific interest. Therefore, the competitive adsorption of multi-component benzene, toluene, and xylene (BTX) vapors by the DBCB-AC was elucidated. In the single-component system, the adsorption capacities of the BTX vapors at inlet concentrations of 20 mg/L were determined as 495, 580, and 674 mg/g, respectively. In contrast, in the binary-component system, the adsorption capacity of the B-vapor at 20 mg/L B + 10 mg/L T and 20 mg/L B + 10 mg/L X decreased by approximately 42% and 56%, respectively. Similarly, the adsorption capacity of the T-vapor at 20 mg/L T + 10 mg/L X decreased by approximately 47%. In the ternary-component system, the adsorption capacity of the X-vapor remained consistent. The adsorption mechanism of the BTX was explained by adsorption kinetic and isotherm models. The reuse efficiency of the DBCB-AC for the BTX was assessed through five cycles of adsorption-desorption tests and was found to be 89.45%, 88.02%, and 87.25%, respectively. The DBCB-AC, which had high-performance in terms of both reuse efficiency and adsorption capacity, can be recommended as a promising adsorbent for removal of VOC pollutants.

Removal of gaseous benzene by a fixed-bed system packed with a highly porous metal-organic framework (MOF-199) coated glass beads

The utility of nanomaterial adsorbents is often limited by their physical features, especially fine particle size. For example, a large bed-pressure drop is accompnied inevitably, if fine-particle sorbents are used in a packed bed system. To learn more about the effect of adsorbent morphology on uptake performance, we examined the adsorption efficiency of metal-organic framework 199 (MOF-199) in the pristine (fine powder) form and after its binding on to glass beads as an inert support. Most importantly, we investigated the effect of such coatings on adsorption of gaseous benzene (0.1–10 Pa) in a dry N2 stream, particularly as a function of the amount of MOF-199 loaded on glass beads (MOF-199@GB) (i.e., 0,% 1%, 3%, 10%, and 20%, w/w) at near-ambient conditions (298 K and 1 atm). A 1% MOF-199 load gave optimal performance against a 0.1 Pa benzene vapor stream in 1 atm of N2, with a two-to five-fold improvement (e.g., in terms of 10% breakthrough volume [BTV] (46 L atm [g.MOF-199)−1], partition coefficient at 100% BTV (3 mol [kg.MOF-199]−1 Pa-1), and adsorption capacity at 100% BTV (20 mg [g.MOF-199]−1 (areal capacity: 8.8 × 10−7 mol m−2) compared with those of 3%, 10%, and 20% loading. The relative performance of benzene adsorption was closely associated with the content of MOF-199@GB (e.g., 1% > 3% > 10% > 20%) and the surface availability (m2 [g.MOF-199]−1) such as 291 > 221 > 198 > 181, respectively. This study offers new insights into the strategies needed to expand the utility of finely powdered MOFs in various environmental applications.

A UiO-66 3D photonic crystal optical sensor for highly efficient chlorobenzene vapor detection.

Chlorobenzene (C6H5Cl) is a flammable liquid with high vapor activity, which is a severe threat to the environment and human health. Therefore, it is essential to develop a highly efficient sensor to detect C6H5Cl vapor. Herein, we developed a UiO-66 three-dimensional photonic crystal (3D PC) optical sensor and investigated its sensing properties toward the C6H5Cl vapor. The UiO-66 3D PCs optical sensor shows a high sensitivity of C6H5Cl vapor, in the concentrations range of 0-500 ppm, the reflectance intensity response to be 0.06% ppm with a good linear relationship, detection limit can reach 1.64 ppm and the quality factor is 10.8. Additionally, the UiO-66 3D PC optical sensor demonstrated great selectivity with the values of selectivity (S) varying from 2.24 to 10.65 for the C6H5Cl vapor as compared with carbon tetrachloride (CCl4), dichloromethane (CH2Cl2), 1,1,2-trichloroethane (C2H3Cl3), benzene (C6H6), deionized water (H2O), ethanol (C2H5OH) and methyl alcohol (CH3OH) vapors. Moreover, the UiO-66 3D PC optical sensor shows an ultrafast optical response time and recovery times of 0.5 s and 0.45 s with exceptional stability and repeatability to 500 ppm C6H5Cl vapor. These excellent sensing properties are attributed to the efficacy of signal transduction, increased porosity and gas adsorption sites, which are intrinsically endowed by the design of the 3D optical structure. The design and fabrication of this UiO-66 3D PC optical sensor might open up potential applications for the detection of the C6H5Cl vapor.

Cagearenes: synthesis, characterization, and application for programmed vapour release.

Here, we announce the establishment of a new family of organic molecular cages, named cagearenes, by taking advantage of a versatile strategy. These cagearenes were prepared via the Friedel–Crafts reaction by condensing two equivalents of a precursor bearing three 1,4-dimethoxybenzene groups and three equivalents of formaldehyde. Two cages, namely cagearene-1 and cagearene-2, are obtained and well characterized. The cagearene-1 solid exhibits the ability to adsorb benzene vapour from an equimolar benzene/cyclohexane mixture with a purity of 91.1%. Then, the adsorbed benzene molecules can be released from the cage at a relatively lower temperature, namely 70 °C, as a consequence of which, cyclohexane with a high purity was left within the cage solid. Heating the cage solid further at 130 °C led to the production of cyclohexane with a purity up to 98.7%. As inferred from the single crystal structures and theoretical calculations, the ability of the cage in programmed release of benzene and cyclohexane results from the different binding modes of these two guests.

A vapochromic dye/graphene coated long-period fiber grating for benzene vapor sensing

A vapochromic dye was synthesized and coated on a long-period fiber grating sensor for specific benzene vapor sensing with an ultra-large dynamic range.

Removal of benzene vapor from the air based on novel tantalum metal-organic framework (Ta-MOF) adsorbent by gas flow solid-phase interaction before determination by gas chromatography

‌Benzene has a carcinogenic effect on the human body and adsorption from the air is the best way to control it. By this research, benzene vapor was removed from the air based on a tantalum metal-organic framework (Ta-MOF) by gas flow solid-phase interaction (GF-SPI). Benzene adsorption with Ta-MOF was studied in the static and dynamic systems at room temperature. The benzene concentration was analyzed by gas chromatography equipped with an FID detector (GC-FID). The factors affecting benzene removal efficiency like initial concentration of benzene, amount of adsorbent, exposure time, flow rate, and temperature were studied and optimized. The results showed us, the adsorption capacities range of Ta-MOF for benzene in the static and dynamic system were obtained between 90-160 mg g-1 and 65-135 mg g-1, respectively. Also, the high removal efficiency was achieved by more than 95% at 45°C, 67.5 mg L-1 benzene concentration, 0.5 g of Ta-MOF, and the flow rate of 250 mL min-1 for a dynamic system. By dynamic system, the benzene is generated in the chamber, stored in a bag, and then moved on the surface of Ta-MOF. The GF-SPI method was validated by GC-MS and spiking real samples.

Generation of Phenol and Molecular Hydrogen through Catalyst-Free C-H Activation of Benzene by Water Radical Cations.

Here, we report on the abundant formation of phenol and molecular hydrogen when benzene vapor was exposed to gas plasma generated by +5.5 kV corona discharge of water vapor in argon in the absence of oxygen. Systematic analysis using a series of isotopic standards (d6-benzene, D2O, and H218O) and benzene derivatives (mono-, di-, trichlorobenzene, and N,N-dimethylaniline) indicated that the formation of phenol occurred through the reaction between neutral benzene and the radical cation of water dimer, (H2O)2+•. A two-step reaction mechanism was proposed based on the results of experiments and DFT calculations: (1) the formation of (C6H6...H2O)+• intermediate through electrophilic addition; (2) the formation of C6H5OH+• through the release of H2 from the (C6H6...H2O)+• intermediate. Our findings offer a novel catalyst-free method to prepare phenol from benzene with phenol selectivity >90%.

Macrocycle-Functionalized RGO for Gas Sensors for BTX Detection Using a Double Transduction Mode

To fabricate mass and resistive sensors based on reduced graphene oxide (RGO), we investigated the functionalization of RGO by tetra tert-butyl phthalocyanine (PcH2tBu), which possesses a macroring and tert-butyl peripheral groups. Herein, we present the gas sensor responses of the functionalized RGO toward benzene, toluene, and xylene (BTX) vapors. The RGO was obtained by the reduction of graphene oxide (GO) using citrate as a reducing agent, while the functionalization was achieved non-covalently by simply using ultrasonic and heating treatment. The sensor devices based on both QCM (quartz crystal microbalance) and resistive transducers were used simultaneously to understand the reactivity. Both the GO and the RGO showed less sensitivity to BTX vapors, while the RGO/PcH2tBu presented enhanced sensor responses. These results show that the p-network plays a very important role in targeting BTX vapors. The resistive response analysis allowed us to state that the RGO is a p-type semiconductor and that the interaction is governed by charge transfer, while the QCM response profiles allowed use to determine the differences between the BTX vapors. Among BTX, benzene shows the weakest sensitivity and a reactivity in the higher concentration range (>600 ppm). The toluene and xylene showed linear responses in the range of 100–600 ppm.