Detection Of Benzene Research Articles

Trace detection of benzene, toluene and xylene (BTX) by chemiresistive metal oxide-based gas sensors: Recent advances in heterojunction materials design

Trace detection of benzene, toluene and xylene (BTX) by chemiresistive metal oxide-based gas sensors: Recent advances in heterojunction materials design

The influence of Rh-doped SnO2 microspheres on the sensitivity of benzene detection

In this article, Rh-doped SnO2 microspheres were prepared by a convenient hydrothermal treatment. Compared with the non-doped SnO2 microspheres, the Rh-doped SnO2 microspheres had larger specific surface area, faster electron transfer rate and increased oxygen vacancies, which is beneficial to improve the gas sensitivity of the material. The optimal sensitivity was observed of Rh-0.1 at 250 °C, and the response-recovery time of Rh-0.1 were 46 and 25 s, respectively. Besides, the Rh-doped SnO2 microspheres exhibited excellent gas selectivity and stability to benzene vapor. The novel Rh-doped SnO2 microspheres are potential gas detection materials for accessing benzene vapor.

BODIPY-based fluorescent sensor material for airborne acetone and benzene with aggregation-driven selectivity

Paper highlights advances in design of fluorescent sensors for solvent vapors with boron-dipyrromethene (BODIPY) as a model active component. The present study demonstrates that BODIPY-based fluorescent materials could be successfully utilized for detection of benzene and acetone in gas phase. Concentration of luminophore was found to affect sensory response to benzene (up to 3-fold increase in adjusted conditions). At the same time, sensory response to acetone is concentration-independent, suggesting different underlying response mechanisms and allowing to tune selectivity with choice of concentration. Detection limits achieved for sensory materials are 1.2·104 mg/m3 for acetone and 0.94·104 mg/m3 for benzene. Ultimately, obtained sensor materials could be completely regenerated without need for inert gas purge.

Nano-sculptured vanadium oxide thin films for benzene detection

DC magnetron sputtering was used to prepare nano-sculptured vanadium oxide thin films and their gas sensing properties were investigated for the detection of benzene traces in the air. Oblique nano-structures showed excellent responses to benzene, as well as good repeatability and stability, which makes it a very reliable sensor for the detection of very low concentrations of benzene (a few ten ppbs) in air and under realistic conditions of humidity, as high as 60 % RH at 25 °C.

Visible light enhanced selective benzene response of hexagonal atomic structured CuS microcloves

We have reported CuS microcloves (MCs) for highly selective detection of benzene using scanning kelvin probe (SKP) technique. The electron microscopy investigations revealed the formation of clove shaped CuS with a size of about 1–2 µm at 180 °C and 6 h. The time of reaction significantly affected the crystallinity as well as the morphology of resulting CuS materials. The investigations on adsorption behavior of different types of common volatile organic compounds (VOCs) with varying charge and nature revealed an outstanding selectivity towards benzene when compared to other VOCs. The difference in work function between gold tip and sensor surface modified with CuS MCs was decreased under the exposure of light, most likely caused by transfer of electrons to conduction band of CuS under illumination of light. As a result, the CuS MCs showed enhanced photo response in visible light exposure in the presence of benzene. A chemiresistive type sensor device was fabricated using CuS MCs and exposed to benzene vapor in a concentration ranging from 2.8 to 11.2 ppm. The sensitivity was found to be 1.63 × 10-3 ppm−1. Notably, a rapid response time of ∼6 s and recovery time of ∼ 16 s was achieved for the sensor at a benzene concentration of 5.6 ppm at room temperature. Also, considerable and repeatable sensor response was observed for 560 ppb of benzene vapor at 70 °C. Hence, these results suggested that the CuS MCs have huge potential as novel material for selective benzene detection in gas phase towards breath analysis and other environmental monitoring.

Highly sensitive and selective laser-based BTEX sensor for occupational and environmental monitoring

A mid-infrared laser-based sensor is designed and demonstrated for trace detection of benzene, toluene, ethylbenzene, and xylene isomers at ambient conditions. The sensor is based on a distributed feedback inter-band cascade laser emitting near 3.29 µm and an off-axis cavity-enhanced absorption spectroscopy configuration with an optical gain of 2800. Wavelength tuning and a deep neural network (DNN) model were employed to enable simultaneous and selective BTEX measurements. The sensor performance was demonstrated by measuring BTEX mole fractions in various mixtures. At an integration time of 10 s, minimum detection limits of 11.4, 9.7, 9.1, 10, 15.6, and 12.9 ppb were achieved for benzene, toluene, ethylbenzene, m-xylene, o-xylene, and p-xylene, respectively. The sensor can be used to detect tiny BTEX leaks in petrochemical facilities and to monitor air quality in residential and industrial areas for workplace pollution.

Power-modulated integrated path differential absorption lidar for probing benzene concentration.

Aimed at the regional open-path detection of benzene (C 6 H 6) in the atmosphere, a power-modulated integrated path differential absorption (PM-IPDA) lidar is introduced and demonstrated. Two tunable interband cascade lasers (ICLs) with about 3.2µm wavelength are utilized to generate the required PM optical signal. These two operation central wavelengths (CWs) of the PM-IPDA lidar are, respectively, 3236.6 and 3187.1nm, which can mitigate the influence of significant gases such as H 2 O, C H 4, and HCl on the detection performance. In this work, the fast Fourier transform algorithm is used to retrieve the measured values with the time resolution of 0.1s corresponding to 104 sampling bins at the sampling rate of 100kSps/s. The modulated frequency of the PM-IPDA lidar is selected as 10kHz by laboratory experiments. The slow fluctuation characteristic of the benzene absorption spectrum within the vicinity region of 3.2µm reduces the impact of small wavelength fluctuations on the performance of PM-IPDA lidar, although a scheme modulated only the driving current causes wavelength fluctuations of ∼±0.2n m. These laboratory experiments also indicate the PM-IPDA lidar can reduce the error resulting from 1/f noise. Open-path observation experiments show that the detection limit is about 0.60m g⋅m -3 and that the PM-IPDA lidar can be used for the regional open-path real-time detection of benzene.

Simultaneous voltammetric detection of benzene, naphthalene and anthracene from water using boron-doped diamond electrode

In this study, a simple, fast and sensitive voltammetric detection using boron-doped diamond (BDD) electrode was proposed for simultaneous quantification of benzene (BZ), naphthalene (NF) and anthracene (AC) from priority organic pollutants class in real tap water. The electrochemical behaviors of individual and simultaneous BZ, NF and AC studied by cyclic voltammetry (CV) on BDD electrode showed a large separation between their oxidation potential, which allowed the development of simple simultaneous detection method. Differential-pulse voltammetry (DPV) technique operated at step potential of 5 mV and modulation amplitude of 200 mV enabled to reach the lowest limits of detection of 0.40 μM for BZ, 0.04 μM for NF and 0.70 nM for AC, which is appropriate for water quality control related to their environmental quality standards. No significant influence of chloride ions was found and the method was validated in real tap water and surface water spiked with known concentrations of BZ, NF and AC, which proved the practical utility of the method for water quality control.

Miniature Optical Fiber Fabry-Perot Interferometer Based on a Single-Crystal Metal-Organic Framework for the Detection and Quantification of Benzene and Ethanol at Low Concentrations in Nitrogen Gas.

This study reports for the first time, to the best of our knowledge, a real-time detection of ultralow-concentration chemical gases using fiber-optic technology, combining a miniaturized Fabry-Perot interferometer (FPI) with metal-organic frameworks (MOFs). The sensor consists of a short and thick-walled silica capillary segment spliced to a lead-in single-mode fiber (SMF), housing a tiny single crystal of HKUST-1 MOF, imparting chemoselectivity features. Ethanol and benzene gases were tested, resulting in a shift in the FPI interference signal. The sensor demonstrated high sensitivity, detecting ethanol gas concentrations (EGCs) with a sensitivity of 0.428 nm/ppm between 24.9 and 40.11 ppm and benzene gas concentrations (BGCs) with a sensitivity of 0.15 nm/ppm between 99 and 124 ppm. The selectivity study involved a combination of three ultralow concentrations of ethanol, benzene, and toluene gases, revealing an enhancement factor of 436% for benzene and 140% for toluene, attributed to the improved miscibility of these conjugated ring molecules with the alkane chains of the ethanol-modified HKUST-1. Experimental tests confirmed the sensor's viability, demonstrating significantly improved response time and spectral characteristics through crystal polishing, indicating its potential for quantifying and detecting chemical gases at ultralow concentrations. This technology may prevent energy resource losses, and the sensor's small size and robust construction make it applicable in confined and hazardous locations.

Design and Performance Evaluation of Machine Learning-based Terahertz Metasurface Chemical Sensor.

This paper presents a terahertz metasurface based sensor design incorporating graphene and other plasmonic materials for highly sensitive detection of different chemicals. The proposed sensor employs the combination of multiple resonator designs - including circular and square ring resonators - to attain enhanced sensitivity among other performance parameters. Machine learning techniques like Random Forest regression, are employed to enhance the sensor design and predict its performance. The optimized sensor demonstrates excellent sensitivity of 417 GHzRIU-1 and a low detection limit of 0.264 RIU for ethanol and benzene detection. Furthermore, the integration of machine learning cuts down the simulation time and computational requirements by approximately 90% without compromising accuracy. The sensor's unique design and performance characteristics, including its high-quality factor of 14.476, position it as a promising candidate for environmental monitoring and chemical sensing applications. Moreover, it also demonstrates potential for 2-bit encoding applications through strategic modulation of graphene chemical potential values. On the other hand, it also shows prospects of 2-bit encoding applications via the modulation of graphene chemical. This work provides a major advancement to the terahertz sensing application by proposing new materials, structures, and methods in computation in order to develop a high-performance chemical sensor.

Scandia-doped zirconia for the electrochemical detection of hazardous dihydroxybenzene (DHB) isomers in water.

In this paper, modified yttria- and scandia-doped zirconium oxide were exploited for the development of an effective electrochemical sensor for the simultaneous detection of dihydroxy benzene (DHB) isomers, i.e. hydroquinone...

Identification and Limit of Detection of Benzene, Chlorobenzene, Benzoic Acid, Phthalic Acid, and Mellitic Acid in Water Solutions Using Excitation, Emission, and Single-band Synchronous Fluorescence Spectroscopy

Introduction: This paper first introduces the use of computer-simulated single-band synchronous fluorescence (SF) obtained from experimental excitation and emission fluorescence spectra of a pure compound in solution. The simulation produces a single narrow band with a peak wavelength that identifies the compound. Methods: The method is used to show single peak identification of benzene, chlorobenzene, benzoic acid, phthalic acid, and mellitic acid in water solutions. Synchronous fluorescence spectroscopy (SFS) is a variant of fluorescence technique in which excitation and emission scans are simultaneously acquired and multiplied with a predetermined wavelength difference (Δλ) between the two. Commercial instruments have this option to get the SFS signals. Results: In response to the Δλ selected, the result will be an SFS signal producing a series of peaks that could be assigned to compounds. Instead of running the same experiment with different Δλ values to identify the compounds, our simulation program determines a specific Δλ value that generates a narrow SF band with a distinctive peak wavelength for identification purposes. Conclusion: Finally, binary mixtures of chlorobenzene with each compound in water are prepared. The SFS of the solution is acquired and compared with the SFS bands of the components for identification purposes. With the commercial lamp fluorimeter employed, the limits of detection are obtained at the ng/g concentration level with fluorescence emission. Possible limits of detection at lower concentrations are discussed using a laser source. The presence of these molecules in astrochemical studies is discussed.

Application of Sonotriboluminescence to Determine Arene Molecules in Hydrocarbons

The sonotriboluminescence of suspensions of terbium(III) and europium(III) sulfates in decane without and in the presence of benzene, toluene and p-xylene was studied. The choice of crystals of these lanthanides is due to the fact that they have intense luminescence during mechanical action, and also do not dissolve in hydrocarbon solvents. During ultrasonic exposure to suspensions in pure alkanes, bands of Ln3+ ions and N2 in the UV region are recorded in the luminescence spectrum. When aromatic hydrocarbon molecules are added, bands of benzene, toluene and p-xylene molecules, coinciding with their photoluminescence spectra, are recorded in the sonotriboluminescence spectra in the UV region. The high sensitivity of the luminescence of suspensions to arene additives made it possible to obtain the dependence of the characteristic fluorescence of arene molecules in the sonotriboluminescence spectra on their concentration in suspensions. The limits of detection of benzene, toluene and p-xylene in the composition of this suspension were established. The lower limits of detection from the sonotriboluminescence spectra for xylene, toluene and benzene are 0.1, 3 and 50 ppmv, respectively. Fluorescence bands of these molecules were also recorded in the sonotriboluminescence spectra of suspensions in commercial dodecane and heptane with additives of commercial gasoline (up to 1%). The results obtained can be used for luminescent detection of aromatic compounds in saturated hydrocarbons.

Fabrication of metal-organic frameworks derived Co3O4 loaded on TiO2: Influence of Fe loading on the Co3O4/TiO2 heterostructure for low-ppm benzene detection

We report the low-concentration detection of benzene using a metal–organic framework (MOF) derived Co3O4/TiO2 heterostructures loaded with 0.5–2 wt.% Fe synthesized using the co-precipitation method. The intrinsic properties of the heterostructures, such as their surface crystal structures, adsorption states, and chemical states, were examined. The sensing properties of the sensors were tested for nine (9) gases, including benzene, toluene, ethylbenzene (BTE), ethanol, acetone, carbon monoxide (CO), methane (CH4), carbon dioxide (CO2), and nitrogen dioxide (NO2) at various temperatures. The 1.0 wt.% Fe/Co3O4/TiO2 heterostructure-based sensor disclosed higher responses of ∼ 3 toward 2 ppm benzene at 175 °C. Furthermore, the sensor was able to experimentally detect benzene as low as 0.35 ppm and exhibited a low theoretical limit of detection (∼4.17 ppb) toward benzene at 175 °C, which increased at higher temperatures. The sensors were very stable in dry air and 20 % RH for 25 days. We infer that the excellent benzene detection could be associated with the loading of Fe3+ on the surface of the Co3O4/TiO2, which increased the specific surface area, narrowed the band gap, and provided numerous oxygen vacancies. Finally, the sensing mechanism linked with the loading of Fe3+ on the surface of Co3O4/TiO2 is discussed in detail.

Detection of Aromatic Hydrocarbons in Aqueous Solutions Using Quartz Tuning Fork Sensors Modified with Calix[4]arene Methoxy Ester Self-Assembled Monolayers: Experimental and Density Functional Theory Study.

Quartz tuning forks (QTFs), which were coated with gold and with self-assembled monolayers (SAM) of a lower-rim functionalized calix[4]arene methoxy ester (CME), were used for the detection of benzene, toluene, and ethylbenzene in water samples. The QTF device was tested by measuring the respective frequency shifts obtained using small (100 µL) samples of aqueous benzene, toluene, and ethylbenzene at four different concentrations (10-12, 10-10, 10-8, and 10-6 M). The QTFs had lower limits of detection for all three aromatic hydrocarbons in the 10-14 M range, with the highest resonance frequency shifts (±5%) being shown for the corresponding 10-6 M solutions in the following order: benzene (199 Hz) > toluene (191 Hz) > ethylbenzene (149 Hz). The frequency shifts measured with the QTFs relative to that in deionized water were inversely proportional to the concentration/mass of the analytes. Insights into the effects of the alkyl groups of the aromatic hydrocarbons on the electronic interaction energies for their hypothetical 1:1 supramolecular host-guest binding with the CME sensing layer were obtained through density functional theory (DFT) calculations of the electronic interaction energies (ΔIEs) using B3LYP-D3/GenECP with a mixed basis set: LANL2DZ and 6-311++g(d,p), CAM-B3LYP/LANL2DZ, and PBE/LANL2DZ. The magnitudes of the ΔIEs were in the following order: [Au4-CME⊃[benzene] > [Au4-CME]⊃[toluene] > [Au4-CME]⊃[ethylbenzene]. The gas-phase BSSE-uncorrected ΔIE values for these complexes were higher, with values of -96.86, -87.80, and -79.33 kJ mol-1, respectively, and -86.39, -77.23, and -67.63 kJ mol-1, respectively, for the corresponding BSSE-corrected values using B3LYP-D3/GenECP with LANL2dZ and 6-311++g(d,p). The computational findings strongly support the experimental results, revealing the same trend in the ΔIEs for the proposed hypothetical binding modes between the tested analytes with the CME SAMs on the Au-QTF sensing surfaces.

Environmental Assessment of Soil and Groundwater Pollution by BTEX Leaching in Valencia Region (Spain)

The impact of hydrocarbon spills in the unsaturated zone is a significant environmental concern, particularly in locations where contamination arises from leaks in underground fuel storage tanks (USTs). This paper presents the outcomes achieved through the utilization of VLEACH, a finite-difference numerical model, to assess the concentrations of organic contaminants in the solid, liquid, and gas phases within the vadose zone. Additionally, it evaluates the mass transfer of pollutants to the aquifer as part of an environmental assessment for the placement of a forthcoming service station. The study encompasses an analysis of 18 scenarios under realistic conditions based on actual field data. These scenarios were constructed, taking into account various factors, including the nature of the leak (one-time or permanent), the depth of the phreatic level, and the soil conditions and properties. The results highlight the potential environmental consequences of a permanent leak as compared to those resulting from a specific accident. The findings further emphasize the substantial influence of soil moisture on transport phenomena within the vadose zone. Variations in soil moisture significantly alter hydraulic conductivity, impact magnitudes, transport velocities, and even the predominant transport mechanism. Consequently, precise delineation of soil moisture becomes a crucial parameter in such simulations. Additionally, it has been observed that each component of BTEX (benzene, toluene, ethylbenzene, and xylene) experiences varying transport velocities through the vadose zone. Benzene, having a greater propensity to concentrate in the liquid and gas phases, exhibits the swiftest movement through the vadose zone. The detection of benzene in aquifers can serve as an indicator of the potential future arrival of the remaining BTEX compounds.

A laser-based sensor for selective detection of benzene, acetylene, and carbon dioxide in the fingerprint region

A laser-based sensor for selective detection of benzene, acetylene, and carbon dioxide in the fingerprint region

Design of an Intelligent Sensor System Based on Fluorescence Analysis

In response to the current problems of serious pollution of typical organic substances in groundwater systems at petrochemical production sites, high cost of detection equipment, non-portability, low accuracy, and poor stability, a smart sensor for benzene and PAHs was proposed based on the fluorescence analysis method. The relationship curve between concentration and absorbance was derived using Lambert’s law from the different wavelengths and peaks of the absorbed light of different substances and was used to detect the concentration of organic substances. The experimental results showed that the online organic detection sensor based on fluorescence analysis had good stability for the detection of benzene and benzo(b)fluoranthene in groundwater systems at petrochemical production sites and could detect organic concentrations accurately and efficiently, providing data support for environmental protection and wastewater treatment. The method was low cost, simple in structure, high in detection accuracy, and good in interference immunity to meet analytical testing requirements.

Highly sensitive and selective detection of benzene, toluene, xylene, and formaldehyde using Au-coated SnO2 nanorod arrays for indoor air quality monitoring

We report the high performance of Au-coated SnO2 nanorod gas sensors for the detection of hazardous indoor volatile organic compounds (VOCs), such as benzene, toluene, xylene, and formaldehyde (BTXF) gases. Densely ordered SnO2 nanorod arrays were prepared via glancing angle deposition with an electron beam evaporator. The Au layer coating was used as a heterogeneous catalyst to promote the oxidation of VOCs, such as hydrocarbons. After optimizing the Au thickness, the sensor exhibited an excellent sensing response and a rapid response time of < 2.5 s for 10 ppm of BTXF gases. The maximum response was ∼662 for formaldehyde at 400 °C, ∼328 for toluene at 450 °C, ∼170 for xylene at 400 °C, and ∼139 for benzene at 500 °C, which are significantly higher than those of previously reported metal-oxide-semiconductor-based sensors. Each gas was selectively detected by integrating the sensor into a miniaturized gas chromatography (GC) system. The sensors detected ppb-level gas concentrations. Significantly, GC analysis revealed that four types of gases could be separately detected in a mixed gas within 5 min. Our study shows that Au-coated SnO2 nanorod gas sensors integrated with GC can be used as a facile indoor pollutant monitoring system.

SAW Sensor with Langmuir-Blodgett Layer for Detection of Benzene and its Derivatives

Vapors of benzene and its derivatives are harmful and toxic for human beings and natural environment. Their detection has fundamental importance. For this purpose authors propose surface acoustic wave (SAW) sensor with skeletonized layer deposited by Langmuir-Blodgett (L-B) method. This layer was obtained by depositing a binary equimolar mixture of 5-[[1,3-dioxo-3-[4-(1-oxooctadecyl) phenyl]propyl]amino]–1,3–benzenedicarboxylic acid with cetylamine. The skeletonized sensor layer has been obtained by removing cetylamine. Response of this sensor depends mainly of the electrical dipole momentum of molecule. Among the tested compounds, benzene has a zero dipole moment and gives the smallest sensor response, and nitrobenzene has the largest dipole moment and the sensor reacts most strongly to its vapor.