塑料挥发物长光程FTIR测量方法

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

塑料产品除了在自然环境中可降解为微塑料污染环境之外,还会产生挥发性有机物,同样对环境造成巨大的污染和危害,因此对塑料挥发物的测量就显得尤为重要。目前传统挥发物的测量方法,如环境质谱法和色谱法等,存在测量过程复杂,成本高,无法实时测量等缺点,因而需要一种快速有效的针对塑料挥发物的测量方法。采用傅里叶变换红外光谱仪(Fourier transform infrared spectrometer,FTIR Spectrometer)结合怀特池对塑料挥发物进行测量,但是由于抽取式傅里叶变换红外光谱仪本身灵敏度有限,很难实现微量的塑料挥发物的测量,所以针对这一问题,尝试通过长光程气体池提高常规傅里叶变换红外光谱仪的灵敏度从而实现不同种类塑料挥发物的测量。选取了5种塑料产品,分别是低密度聚乙烯(LDPE),高密度聚乙烯(HDPE),聚乙烯(PE),聚对苯二甲酸乙二醇酯(PET),聚丙烯(PP),利用光程长为20 m的怀特池结合傅里叶变换红外光谱仪实现了其中一些挥发物的光谱特征观测,实验观察到所有种类的塑料在2个光谱波数段具有明显的光谱特征,分别为800~850和1050~1150 cm^(-1)。除聚对苯二甲酸乙二醇酯(PET)外,其余4种塑料挥发物在2800~3000 cm^(-1)还存在明显的光谱吸收波段。进一步又研究了不同温度条件下塑料产生的挥发物,通过分析不同温度条件下的塑料产生的挥发物的红外光谱,发现除低密度聚乙烯(LDPE)在两种温度条件下光谱差异较大外,其他种类的塑料挥发物红外光谱差异较小。该研究提出了一种新型的基于长光程FTIR的塑料挥发物的测量方法,证实了其在塑料挥发物测量方面的有效性,这种方法具有测量成本低,可连续观测,实时在线等优点,为实现连续在线的塑料挥发物排放通量监测奠定了基础。

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 800~850 and 1050~1150 cm^(-1) respectively.In addition to polyethylene terephthalate(PET),the other four plastic volatiles also have obvious spectral absorption bands at 2800~3000 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.