High Sensitivity Continuous Monitoring of Chloroform Gas by Using Wavelength Modulation Photoacoustic Spectroscopy in the Near-Infrared Range

Zhang, Tie; Xing, Yanpeng; Wang, Gaoxuan; He, Sailing

doi:10.3390/app11156992

Cited by 11 publications

(3 citation statements)

References 36 publications

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“…As for PAS, it generates acoustic signals from the sample being detected through the photoacoustic effect and analyzes these acoustic signals to determine the composition and concentration of samples. Benefiting from this, PAS has found extensive applications in environmental monitoring, industrial process control and monitoring, medical diagnostics, and national defense hazardous material detection [66,67]. Laser spectroscopy techniques exploit the unique infrared absorption peaks of various target gases for measurements.…”

Section: Voc In Situ Monitoring Technologymentioning

confidence: 99%

Volatile Organic Compounds (VOCs) in Soil: Transport Mechanisms, Monitoring, and Removal by Biochar-Modified Capping Layer

Wang,

Song,

et al. 2024

Coatings

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Volatile organic compounds (VOCs), as a primary pollutant in industrial-contaminated sites or polluted soils, cause severe damage to the soil. Therefore, a comprehensive understanding of the transport of VOCs in soil is imperative to develop effective detection means and removal methods. Among them, biochar possesses potential advantages in the adsorption of VOCs, serving as an effective method for removing VOCs from soil. This review provides an overview of the VOCs within soil, their transport mechanisms, monitoring technology, and removal approach. Firstly, the historical development of the VOC migration mechanism within the capping layer is described in detail. Secondly, the in situ monitoring techniques for VOCs are systematically summarized. Subsequently, one of the effective removal technologies, a capping layer for polluted sites, is simply introduced. Following this, the potential application of a biochar-modified capping layer for the removal of VOCs is comprehensively discussed. Finally, the major challenges in the field and present prospects are outlined. The objective of this study is to furnish researchers with a foundational understanding of VOCs, their relevant information, and their removal approach, inspiring environmental protection and soil pollution control.

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Section: Voc In Situ Monitoring Technologymentioning

confidence: 99%

Volatile Organic Compounds (VOCs) in Soil: Transport Mechanisms, Monitoring, and Removal by Biochar-Modified Capping Layer

Wang,

Song,

et al. 2024

Coatings

View full text Add to dashboard Cite

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“…16) based on electret microphones for simultaneous detection of trichloromethane (CHCl3) and dichloromethane (CH2Cl2) by employing a low-cost distributed feedback (DFB) laser emitting at 1684 nm. Continuous monitoring of Chloroform Gas with a high detection sensitivity of 280 ppbv was achieved [73,74].…”

Section: Different Structure Of Pa Spectrometer For Detection Of Vocsmentioning

confidence: 99%

Voc Detections With Optical Spectroscopy

Xing¹,

Wang²,

Zhang³

et al. 2022

PIER

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Volatile organic compounds (VOCs or VOC) have received increasing attention recently. They are important Parameter index for air quality monitoring, and biomarkers for diseases diagnosis. For the gas sensor community, various detection technologies were explored not only to detect total VOCs, but also aim for sensor selectivity. Commercially available VOC sensors, such as metal oxide based or photoionization detectors, are suitable for total VOCs but lack of selectivity. With the advancement of optical spectroscopy, it provides a good solution for specific VOC detections. In this review, various spectroscopy techniques are summarised focusing on increasing sensor selectivity and sensitivity. The techniques considered in the paper are, non-dispersive infrared, multi-pass cell spectroscopy, cavity enhanced absorption spectroscopy, photoacoustic spectroscopy and Fourier transform infrared spectroscopy. Each technique has its advantages and disadvantages, which are also discussed.

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“…There are various physical approaches for developing chloroform sensors. They are based on field-effect transistors [ 4 ], resistivity elements [ 5 ], photoacoustic spectroscopy [ 6 ], optical fibers [ 7 ], etc. An alternative approach is the use of acoustic wave propagation in crystal substrates coated with appropriate sorbent films.…”

Section: Introductionmentioning

confidence: 99%

Langmuir-Blodgett Films of Arachidic and Stearic Acids as Sensitive Coatings for Chloroform HF SAW Sensors

Gorbachev

Smirnov

Ivanov

et al. 2022

Sensors

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Properties of the Langmuir-Blodgett (LB) films of arachidic and stearic acids, versus the amount of the films’ monolayers were studied and applied for chloroform vapor detection with acoustoelectric high-frequency SAW sensors, based on an AT quartz two-port Rayleigh type SAW resonator (414 MHz) and ST-X quartz SAW delay line (157.5 MHz). Using both devices, it was confirmed that the film with 17 monolayers of stearic acid deposited on the surface of the SAW delay line at a surface pressure of 30 mN/m in the solid phase has the best sensitivity towards chloroform vapors, compared with the same films with other numbers of monolayers. For the SAW resonator sensing using slightly longer arachidic acid molecules, the optimum performance was reached with 17 LB film layers due to a sharper decrease in the Q-factor with mass loading. To understand the background of the result, Atomic Force Microscopy (AFM) in intermittent contact mode was used to study the morphology of the films, depending on the number of monolayers. The presence of the advanced morphology of the film surface with a maximal average roughness (9.3 nm) and surface area (29.7 µm2) was found only for 17-monolayer film. The effects of the chloroform vapors on the amplitude and the phase of the acoustic signal for both SAW devices at 20 °C were measured and compared with those for toluene and ethanol vapors; the largest responses were detected for chloroform vapor. For the film with an optimal number of monolayers, the largest amplitude response was measured for the resonator-based device. Conversely, the largest change in the acoustic phase produced by chloroform adsorption was measured for delay-line configuration. Finally, it was established that the gas responses for both devices coated with the LB films are completely restored 60 s after chamber cleaning with dry air.

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High Sensitivity Continuous Monitoring of Chloroform Gas by Using Wavelength Modulation Photoacoustic Spectroscopy in the Near-Infrared Range

Cited by 11 publications

References 36 publications

Volatile Organic Compounds (VOCs) in Soil: Transport Mechanisms, Monitoring, and Removal by Biochar-Modified Capping Layer

Volatile Organic Compounds (VOCs) in Soil: Transport Mechanisms, Monitoring, and Removal by Biochar-Modified Capping Layer

Voc Detections With Optical Spectroscopy

Langmuir-Blodgett Films of Arachidic and Stearic Acids as Sensitive Coatings for Chloroform HF SAW Sensors

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