Measurement of Volatile Compounds Released From Plastic Using Long-Optical-Path FTIR

In addition to degrading into microplastics in the natural environment, plastic products will pollute the environment, but also produce volatile organic compounds, which also cause huge pollution and harm to the environment. Therefore, the measurement of plastic volatiles is particularly important. At present, traditional volatile measurement methods, such as environmental mass spectrometry and chromatography, have disadvantages such as complex measurement processes, high cost, and inability to measure in real time. Therefore, there is a lack of a fast and effective measurement method for plastic volatiles. In this study, Fourier Transform Infrared Spectrometer (FTIR Spectrometer) combined with White Cell was used to measure plastic volatiles. However, due to the limited sensitivity of extractive Fourier Transform Infrared Spectrometer, it is not easy to measure plastic volatiles. Therefore, in response to this problem, we try to improve the sensitivity of conventional Fourier transform infrared spectrometers through a long optical path gas cell to measure different types of plastic volatiles. In this research, we studied 5 kinds of plastic products, namely low density polyethylene (LDPE) high density polyethylene (HDPE) polyethylene (PE) polyethylene terephthalate (PET), Polypropylene (PP) , through the White cell with an optical path length of 20 m combined with a Fourier transform infrared spectrometer to achieve the observation of some of the volatile spectral characteristics. It is observed from the experiment that all types of plastics have two spectral absorption bands. Obvious spectral characteristics at 800 similar to 850 and 1 050 similar to 1 150 cm(-1) respectively. In addition to polyethylene terephthalate (PET) , the other four plastic volatiles also have obvious spectral absorption bands at 2 800 similar to 3 000 cm(-1). We further studied the volatiles produced by plastics under different temperature conditions. By analyzing the infrared spectra of the volatiles produced by plastics under different temperature conditions, we found that, except for low-density polyethylene (LDPE) , the spectra differed significantly under the two temperature conditions. In addition, other types of plastic volatiles have relatively small differences in infrared spectra. This study proposes a new method for measuring plastic volatiles based on long optical path FTIR, which proves its effectiveness in measuring plastic volatiles. This method has the advantages of low measurement cost, continuous observation, real-time online, etc. Lays the foundation for continuous is online monitoring of plastic volatile emission flux.