Path concentration distribution of toluene using remote sensing FTIR and one-dimensional reconstruction method

Area of Science:

• Environmental Science
• Analytical Chemistry
• Spectroscopy

Background:

• Accurate monitoring of air toxic volatile organic compounds (VOCs) like toluene is crucial for environmental and industrial hygiene.
• Traditional methods may lack the spatial resolution or speed required for real-time monitoring.
• Open-Path Fourier-Transform Infrared (FTIR) spectroscopy offers remote sensing capabilities for gas analysis.

Purpose of the Study:

• To develop and validate a one-dimensional mapping technique for reconstructing the spatial concentration distribution of toluene.
• To assess the effectiveness of polynomial fitting and Gaussian modeling for path concentration reconstruction.
• To establish a rapid and intuitive method for monitoring VOCs pollution.

Main Methods:

• Utilized Open-Path remote sensing FTIR coupled with a one-dimensional mapping technique.
• Applied polynomial fitting (degrees 3-7) to Path Integrated Concentrations (PICs) of toluene.
• Developed reconstruction methods using a Gaussian model and the derivative of a 6th-degree polynomial fit.

Main Results:

• The 6th-degree polynomial fitting provided the best fit for toluene PICs.
• Reconstructed toluene concentration distributions using Gaussian modeling and polynomial fitting showed close experimental agreement.
• Identified concentration peaks at approximately 1-2.5 meters with maximum concentrations ranging from 0.78 to 3.19 ppm.

Conclusions:

• The developed one-dimensional mapping technique accurately reconstructs toluene concentration distributions.
• This approach offers fast calculations, precise peak location, and concentration flow mapping capabilities.
• The method is suitable for real-world environmental and industrial hygiene monitoring as a VOCs pollution alert system.