Detection Of Benzene Research Articles

Synthesis of polyacetone acrylamide and detection of amine benzene

A single homogeneous spherical polyacetone acrylamide particles was synthesized by inverse suspension polymerization. By adjusting the conditions of initiator, cross-linking agent, dispersant, water-oil ratio, reaction time and reaction temperature, the adsorbent material with large specific surface area and pore structure was obtained. Polyacetone acrylamide particles can effectively detect aniline by ultraviolet obsorption spectroscopy, the adsorption rate reaches 41.95% within 2 hours, and the adsorption reaches equilibrium within 5 hours, and the adsorption rate reaches 51.30%.

Occupational hazards and risk assessment of benzene-related enterprises in yangzhou city from 2014 to 2018

Objective: To investigate the benzene concentration in the workplace of benzene-related enterprises in Yangzhou City from 2014 to 2018, and the abnormal blood routine of workers exposed to benzene, and to assess their occupational hazards. Methods: The environmental monitoring data of benzene-related enterprises and the health examination data of benzene exposed workers were collected in March 2019. The inhalation risk assessment model of the National Environmental Protection Agency (EPA) was used to assess the carcinogenic and non-carcinogenic risks of benzene workers. Results: The qualified rate of benzene detection in the workplace was 100% from 2014 to 2018, the highest concentration was 1.42 mg/m(3) in five years. The abnormal rates of blood routine detection in benzene exposed workers in five years was 7.10% (213/2 998) 、5.17% (218/4 214) 、5.61% (196/3 493) 、7.65% (288/3 767) 、7.83% (280/3 574) and 7.83%. respectively. The results of risk assessment showed that the minimum carcinogenic risk value was 7.56×10(-6) and the maximum carcinogenic risk value was 31.33×10(-6) in 2014-2018. The hazard quotient values were than 1. Conclusion: Benzene monitoring concentration in benzene-related enterprises in Yangzhou City from 2014 to 2018 was low, which meets the occupational exposure limit in China. However, the abnormal rate of blood routine in five years is still high, and there are both carcinogenic and non-carcinogenic risks. We should pay more attention to the health risk of workers exposed to low concentrat in benzene.

Factors Affecting Urinary tt-Muconic Acid Detection among Benzene Exposed Workers at Gasoline Stations.

Trans, trans-muconic acid (tt-MA) is a metabolite that is widely used as a biomarker to identify low exposure to benzene, a human carcinogen. This study aimed to investigate occupational factors related to the urinary tt-MA detection of benzene exposed workers in gasoline stations. Spot urine samples were collected and analyzed for tt-MA using a high performance liquid chromatography. Additional data were collected via subject interviews using a structured questionnaire. The personal benzene concentration was measured and analyzed by gas chromatography with a flame ionization detector. Results showed that, among the 170 workers, tt-MA was detected in 24.7% of workers and the concentration ranged from 23.0 to 1127.8 µg/g creatinine. Over 25% of those detections possessing tt-MA exceeding the recommended 500 µg/g creatinine was safe. A multiple logistic regression analysis identified that factors significantly associated with the detectable tt-MA were having no other part-time jobs (ORadj = 4.2), personal benzene concentrations of 0.05 ppm or higher (ORadj = 10.3), close to fuel nozzle during refuelling (ORadj = 93.7), and no job training (ORadj = 2.74). Safety training is recommended for those tt-MA detected workers or under a reference benzene concentration of 0.05 ppm or higher. The proposed reference of occupational action level to benzene exposure is 0.05 ppm and compliance could be assessed tt-MA for biomonitoring of those benzene exposed workers.

A novel photochromic metal organic framework based on viologen exhibiting benzene detection and photocontrolled luminescence properties in solid state

A new photochromic and porous Cd (II) metal–organic framework (MOF) has been synthesized by using a robust viologen ligand, named 1-(3-carboxybenzyl)-4,4′-bipyridinium chloride (m-Hbcbpy·Cl) and CdBr2·2H2O. This MOF (Cd–viologen) exhibits fast response and reversible photochromism by electron-transfer (ET) progress due to the viologen radicals formation. Cd–viologen exhibits to select and detect benzenes in solid state due to the electron – deficient properties of m-Hbcbpy·Cl. The benzene detections have been confirmed by visual color changing phenomenon and luminescence quenching experiment. In addition, photo-controlled luminescence properties of this MOF, during the coloration–decoloration process, has been researched.

Tunable laser-based detection of benzene using spectrally narrow absorption features

A mid-infrared laser-based sensor for the detection of gas-phase benzene (C6H6) in ambient air is presented. It is based on the principle of tunable laser absorption spectroscopy utilizing unique fine spectral features of benzene near 3.4 µm, along with the robust design of an optical multi-pass cell. The sensor is capable of providing real-time measurement of benzene as low as 200 ppb (12 ppm m) at 2 Hz, while still being portable enough to fit in the trunk of a small car. A demonstration measurement in a moving vehicle is presented based on the data collected along Highway 101, El Camino Real, and around Stanford University campus in California, showing elevated benzene emission in several spatial regions.

Simultaneous Detection of Hydroquinone, Catechol and Resorcinol by an Electrochemical Sensor Based on Ammoniated-Phosphate Buffer Solution Activated Glassy Carbon Electrode

Abstract An electrochemical sensor was successfully fabricated by coupled ammoniated modification with PBS activation on glassy carbon electrodes (CA-GCE) and characterized by electrochemical impedance spectra. The CA-GCE showed outstanding electrochemical performance, and was applied to simultaneous detection of resorcinol (RC), catechol (CC) and hydroquinone (HQ), which could be ascribed to new active sites by the introduction of amino and oxygen-containing groups and H-bonds formed between hydroxyl groups of RC, CC, and HQ with amine, hydroxyl and carboxyl groups of CA-GCE. The reaction kinetics of RC, CC, and HQ and their reaction on CA-GCE were studied. Experimental results showed that the electrochemical reaction was adsorption controlled. Under the optimal conditions, the linear detection ranges for RC, CC, and HQ were 5–200 μM, 10–300 μM, and 1–300 μM, respectively, with their detection limits of 0.47, 0.23 and 0.46 μM, respectively. Interference and repeatability was further investigated. This strategy opened a new horizon for qualitative and quantitative detection of dihydroxy benzene.

Hydrothermal synthesis of Bi-doped SnO2/rGO nanocomposites and the enhanced gas sensing performance to benzene

In this work, we report on a novel one-pot hydrothermal synthesis of bismuth (Bi)-doped SnO2/rGO nanocomposites. The composite structures, surface morphologies, chemical compositions, optical properties and crystal defects were characterized by XRD, SEM, TEM, BET, FTIR, Raman, XPS, EPR, PL and UV–vis techniques, and the gas sensing properties to benzene (C6H6) were investigated thoroughly by the temperature-controlled CGS-1TP gas sensing test system. Compared with that of the pure SnO2 and rGO/SnO2, the Bi-doped SnO2/rGO presented largely enhanced gas sensing properties to benzene. Its high gas response, fast response-recovery characteristic, good stability and selectivity made Bi-doped SnO2/rGO an ideal sensing material to detect benzene. However, the as-prepared Bi-doped SnO2/rGO based sensor also showed degenerative gas sensing performance at high humidity. The enhanced gas sensing performances of Bi-doped SnO2/rGO could be attributed to the large specific surface area of the composite structure, the unique rGO-SnO2 heterojunctions, the narrowed band gap, and enormous oxygen vacancies. This novel Bi-doped SnO2/rGO composite promises to provide an essential gas sensing material for the detection of benzene.

Surface-enhanced infrared detection of benzene in air using a porous metal-organic-frameworks film

Infrared (IR) spectroscopy is a powerful technique for observing organic molecules, as it combines sensitive vibrational excitations with a non-destructive probe. However, gaseous volatile compounds in the air are challenging to detect, as they are not easy to immobilize in a sensing device and give enough signal by themselves. In this study, we fabricated a thin nanocrystalline metal-organic framework (nMOF) film on a surface plasmon resonance (SPR) substrate to enhance the IR vibration signal of the gaseous volatile compounds captured within the nMOF pores. Specifically, we synthesized nanocrystalline HKUST-1 (nHKUST-1) particles of ca. 80 nm diameter and used a colloidal dispersion of these particles to fabricate nHKUST-1 films by a spin-coating process. After finding that benzene was readily adsorbed onto nHKUST-1, an nHKUST-1 film deposited on a plasmonic Au substrate was successfully applied to the IR detection of gaseous benzene in air using surface-enhanced IR spectroscopy.

Correction to: Surface-enhanced infrared detection of benzene in air using a porous metal-organic-frameworks film

The article Surface-enhanced infrared detection of benzene in air using a porous metal-organic-frameworks film, written by Raekyung Kim*,‡, Seohyeon Jee*,‡, Unjin Ryu*, Hyeon Shin Lee*, Se Yun Kim**,†, and Kyung Min Choi*,†, was originally published on the publisher’s internet portal (currently SPringerLink) on 18 February 2019 with misprinted DOI number, 10.1007/s11814-018-0231-0, due to the technical error from converting manuscript file from Microsoft Word to PDF. The correct DOI number for the article is 10.1007/s11814-019-0315-x.

Tailor-made photonic crystal fiber sensor for the selective detection of formaldehyde and benzene

Abstract Designability and adaptability are of paramount importance in the production and use of photonic crystal fiber (PCF) sensors. It is still challenging to distinguish different gases in fabricating opto-devices and gas sensors for the detection of toxic gases at low concentrations. Here, we explore a tailor-made PCF sensor based on Bragg diffraction. The silicon fiber array acts as the optical fiber cladding, and the air hole serves as the core. The coating materials are carbon nanotubes (CNT) and CdO-CNT composites, which can respectively serve as the selective “turn-on” detectors for perceiving the benzene and formaldehyde by the preferential adsorption. The CNT has a more pronounced response to benzene (0.8 nm/10 ppm) than other gases, while CdO-CNT has strong selectivity to formaldehyde (1.2 nm/10 ppm). The two sensors show strong selectivity, linear sensitivity, and good response recovery capability. The CNT and CdO-CNT coating PCF sensors can play the part of a sensor array to identify benzene and formaldehyde, which have the advantages of easily assembly and excellent selectivity, showing potential for the detection of harmful gases at low concentrations.

Assessing Space, Time, and Remediation Contribution to Soil Pollutant Variation near the Detection Limit Using Hurdle Models to Account for a Large Proportion of Nondetectable Results.

Many emerging, and some legacy, pollutants pose risks to humans and ecosystems near the detection limits (DL) of existing analytical systems. As a result, site assessments and management options are often presented with data sets that are sparse, highly skewed, and left-censored. Existing analysis methods are unable to differentiate effects of treatment from covariates, such as space, obscuring influences of site management. As a case study, we computed the mean and variance of censored soil benzene data across four sites over a three year period by gamma distribution with a maximum likelihood. Further, a combined hurdle model to accommodate left-censored concentrations was applied to analyze factors affecting benzene variation. This approach allowed us to assess the success and spatial dependency of a biostimulatory solution in reducing benzene concentrations at very low concentrations. Benzene concentrations decreased due to the addition of biostimulatory solution and spatial effects, but the detection of soil benzene after biostimulation was highly spatially dependent. By combining computed values for censored observations estimated by the hurdle-gamma model and uncensored observations, we can get the pseudocomplete data sets. The combined model is ideally suited to evaluate existing and emerging pollutants, that pose risks to humans and ecosystems but are typically at or near analytical detection limits.

Polyvinyl Acetate Film-Based Quartz Crystal Microbalance for the Detection of Benzene, Toluene, and Xylene Vapors in Air

Vapors of volatile organic compounds such as benzene, toluene, and xylene (BTX) may cause health concerns. The sensitive detection of these compounds in air remains challenging. In this study, we reported on modification of the Quartz Crystal Microbalance (QCM) sensing chip using polyvinyl acetate (PVAc) film as active coating for the analysis of BTX vapors. The PVAc film was deposited on the QCM sensing chip surface by a spin coating technique. The morphology of the PVAc films was confirmed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The sensitivities of PVAc based QCM system for benzene, toluene, and xylene analyses were 0.018, 0.041, and 0.081 Hz/ppm, respectively. The high sensitivity of the proposed QCM system for analysis of BTX vapors is believed to be due to the effective interaction between the PVAc film and BTX molecules. The analyte vapor pressure appears to also affect the sensitivity. These data show that the prepared QCM sensor has a low time constant, good reproducibility, and excellent stability. It offers an alternative to the developed methods for detection of BTX and possibly other aromatic hydrocarbons in the air.

In-situ photochemical synthesis of Au nanoparticles in polymer matrix with one-component thioxanthone disulfide for detection of benzene, toluene and xylene vapours

Thioxanthonation of diphenyl units of diphenyl disulfide was achieved successfully. The photoreduction and photostabilization ability of 2, 2′-disulfanediylbis (9H-thioxanthen-9-one) was used for in-situ preparation of Au nanoparticles either in solution or in poly(ethylene glycol) methyl ether acrylate / poly(ethylene glycol) diacrylate polymer matrix. SPR(Surface Plasmon Resonance) absorption band of formed Au NPs were recorded at 550 nm by UV–vis spectroscopy. Indeed, formation of elliptical shaped nanoparticles (4–8 μm) as well as spherical ones (11–14 nm) in nanocomposite films were obtained depending on UV irradiation time. DLS (Dynamic Light Scattering) measurements also changed from 440 nm to about 200 nm as a function of irradiation time. The potential of Au NPs/ polymer nanocomposite film as a sensing element for benzene, toluene, xylene (BTX) sensing was studied at different temperatures. An overall evaluation of the experimental results showed that Au NPs/ polymer nanocomposite film has good potential as a sensing element for the detection of BTX vapours.

Elucidation of HEPES Affinity to and Structure on Gold Nanostars.

The zwitterion, N-2-hydroxyethylpiperazine- N'-2-ethanesulfonic acid (HEPES), facilitates the formation and stability of gold nanostars; however, little is known about how this molecule interacts with the metal postsynthesis. Herein, restructuring of gold nanostar morphology is induced upon acidification, an effect that depends on both pH and acid composition as well as on the protonation state of HEPES. Changes in molecular protonation are measured using zeta potential and modeled using DFT. The surface-sensitive technique, surface-enhanced Raman scattering (SERS), reveals that pH variations induce reversible activation of the amine and sulfonate groups in HEPES and that electron redistribution weakens its affinity to the metal thus promoting the adsorption and SERS detection of benzene. By selecting a molecule that does not induce significant desorption of the stabilizing agent, binding energies of benzene to gold are measured even though only weak London dispersion and π-π interactions promote adsorption. All in all, this molecular-level insight is expected to facilitate new applications of these nanostructures in ways that have not been possible to date.

Detection of Benzene and Volatile Aromatic Compounds by Molecularly Imprinted Polymer-Coated Quartz Crystal Microbalance Sensor

The detection of benzene and its analogues are extremely important but difficult without using expensive analytical instruments. The present work reports the detection of aromatic hydrocarbons, such as benzene, toluene, and isomers of xylene, using quartz crystal microbalance sensor. The surface of a silver-coated quartz crystal was coated with a simple solution drop coating method and thermally polymerized in an inert atmosphere for the formation of the sensing film. The polymer was synthesized by copolymerization of the optimum ratio of styrene, divinylbenzene, and tung oil at 90 °C with template. 1, 2, 3 trimethoxybenzene as template performed most efficiently for all the hydrocarbons. Linear calibration curves were observed for all the vapors in the concentration range between 5 and 250 ppm and sensitivities were obtained approximately as 1.645-2.605 Hz/ppm. For benzene, the sensitivity is 2.605 Hz/ppm, which is the highest amongst the reported literature. Thus, minimum concentration of benzene that can be detected is 0.98 ppm. The molecularly imprinted polymer structure and surface morphology were analyzed by FTIR spectroscopy, FESEM, and AFM. The sensitivity of detection of aromatic molecule in this paper by the molecularly imprinted polymer film is found to be the best amongst the reported literature.

Fluorescence-Based Detection of Benzene, Toluene, Ethylbenzene, Xylene, and Cumene (BTEXC) Compounds in Fuel-Contaminated Snow Environments

Reported herein is the sensitive and selective cyclodextrin-promoted fluorescence detection of benzene, toluene, ethylbenzene, xylene, and cumene (BTEXC) fuel components in contaminated snow samples collected from several locations in the state of Rhode Island. This detection method uses cyclodextrin as a supramolecular scaffold to promote analyte-specific, proximity-induced fluorescence modulation of a high-quantum-yield fluorophore, which leads to unique fluorescence responses for each cyclodextrin-analyte-fluorophore combination investigated and enables unique pattern identifiers for each analyte using linear discriminant analysis (LDA). This detection method operates with high levels of sensitivity (sub-micromolar detection limits), selectivity (100% differentiation between structurally similar compounds, such as ortho-, meta-, and para-xylene isomers), and broad applicability (for different snow samples with varying chemical composition, pH, and electrical conductivity). The high selectivity, sensitivity, and broad applicability of this method indicate significant potential in the development of practical detection devices for aromatic toxicants in complex environments.

Highly Selective Detection of Benzene, Toluene, and Xylene Hydrocarbons Using Coassembled Microsheets with Förster Resonance Energy Transfer-Enhanced Photostability.

In this work, highly photostable and fluorescent coassembled microsheets were fabricated from molecules 1 and 2 for sensitive and selective detection of BTX. We demonstrate that Förster resonance energy transfer (FRET) from nonphotostable 1 to photostable 2 gives rise to the high photostability of 1-2 coassembled microsheets. Furthermore, the combined properties of 1 and 2 components in coassembled microsheets allow distinct responses to BTX and other VOC vapors and thereby yield highly sensitive and selective detection of BTX hydrocarbons via FRET. These findings provide a new approach for the development of photostable fluorescence sensors for hazardous chemicals.

Phase inversion enabled energy scavenger: A multifunctional triboelectric nanogenerator as benzene monitoring system

Mechanical energy harvesting using Triboelectric nanogenerator (TENG) based on the coupling of electrostatic induction and contact electrification is a cost-effective and straightforward process. TENG is well known for harnessing the waste energy at a large scale. Here, we demonstrated the fabrication of enhanced-performance TENG in contact-separation mode by utilizing the facile phase inversion process for only one triboactive layer. The phase inversion is a straightforward technique to achieve films with a porous structure and high crystallinity. The non-piezoelectric, semiconducting TiO2 microparticle acts as charge trapping sites attributed to their high dielectric constant. The PVDF-10-TiO2/CA TENG showed 7 times and 10 times enhancement for voltage and short circuit current compared to the PVDF-TiO2/CA TENG prepared without phase inversion process. Furthermore, the device is a multifunctional energy harvester i.e. it can harvest biomechanical as well as wind energy. Finally, we demonstrated the use of TENG device for volatile organic compounds (VOCs) sensing. The device exhibits good response with the change in concentration as well as total flow rate. The voltage decreases with the increase in the benzene concentration. The sensitivity of as fabricated sensor is 0.0035 V/ppm concerning concentration and 0.29176 V/sccm concerning total flow rate. The sensor was integrated with the Arduino Uno for automatic detection of benzene giving the alarm warning for the presence of benzene in the environment. This work extended the application of TENG in the field of VOCs sensing, design and concept which can be applied in the future for the detection of other VOCs in the environment.

Enhanced sensing performance to toluene and xylene by constructing NiGa2O4-NiO heterostructures

The selective detection of methyl benzene (e.g. toluene and xylene) using oxide semiconductor-based gas/vapor sensors is highly desirable but limited by the low chemical reactivity of the benzene compounds. Exploiting p-type semiconductor oxides (e.g., NiO) which provide distinctive catalytic activities for methyl benzene detection is an essential approach. However, the intrinsic responses of p-type semiconductor oxides are often low. In this paper, high-performance toluene and xylene detection has been realized by a sensor based on novel p-p heterojunction NiGa2O4-NiO nanospheres. Construction of optimized p-p heterojunctions, which resulting from the rationally controlling of the NiGa2O4 content in NiGa2O4-NiO, leads to significantly promoted sensing properties for toluene and xylene detection. It is found that the sensor based on 50% NiGa2O4-NiO exhibits the best sensing performances. Its highest response (Rg/Ra = 12.7 to toluene; Rg/Ra = 16.3 to xylene) is almost 10 times higher than that of the pure NiO (Rg/Ra < 2) to 100 ppm toluene and xylene at 230 °C. More importantly, the sensor exhibits superior selectively for detection of the methyl benzene even against more reactive interfering gases/vapors, such as formaldehyde and ethanol. The p-p oxide heterojunction suggests a promising sensing material for toluene and xylene detection with high response, excellent selectivity, good stability and rapid response/recover time.

Low-temperature formation of polycyclic aromatic hydrocarbons in Titan’s atmosphere

The detection of benzene in Titan’s atmosphere led to the emergence of polycyclic aromatic hydrocarbons (PAHs) as potential nucleation agents triggering the growth of Titan’s orange-brownish haze layers. However, the fundamental mechanisms leading to the formation of PAHs in Titan’s low-temperature atmosphere have remained elusive. We provide persuasive evidence through laboratory experiments and computations that prototype PAHs like anthracene and phenanthrene (C14H10) are synthesized via barrierless reactions involving naphthyl radicals (C10H7•) with vinylacetylene (CH2=CH–C≡CH) in low-temperature environments. These elementary reactions are rapid, have no entrance barriers, and synthesize anthracene and phenanthrene via van der Waals complexes and submerged barriers. This facile route to anthracene and phenanthrene—potential building blocks to complex PAHs and aerosols in Titan—signifies a critical shift in the perception that PAHs can only be formed under high-temperature conditions, providing a detailed understanding of the chemistry of Titan’s atmosphere by untangling elementary reactions on the most fundamental level. Small polycyclic aromatic hydrocarbons (PAHs) are thought to be nucleation sites for the growth of Titan’s haze layers. Using laboratory experiments and electronic structure calculations, Zhao et al. show that small PAHs can by synthesized by rapid, barrierless reactions in Titan’s low-temperature environments.