Detection Method Of Volatile Organic Compounds Based On Quartz Tuning Fork Photodetector

As chemical industries highly developed,volatile organic compounds have played a key role in the industrial production process as the raw materials.However,most of them are poisonous,flammable,explosive and they are easy to form organic pollutants,which maybe produce disastrous impact on the production security and social stability.Therefore,it is of vital realistic significance to execute an accurate real-time online monitoring to VOCs,identify and intelligently warn the ingredients of dangerous goods.Mid-infrared laser absorption spectroscopy is widely used in gas detection and analysis in the fields of atmospheric environment and industrial process control due to its nondestructive detection,quick responsiveness and enhanced sensitivity.Currently,the main photoelectric detectors used in this technology are mercury cadmium tellurium(MCT)detector and quantum trap detector,but the overall costs of them are relatively expensive.In addition,the wavelengths or responsive bandwidths of frequencies are limited by the characteristics of the dielectric material employed in the detector,which usually does not meet the full band response in the entire electromagnetic wave ranges.Based on the piezoelectric effect and resonance characteristics of quartz tuning fork(QCTF),a photodetector with low cost and no wavelength response bandwidth limitation is developed in this thesis.The dependence characteristics are studied in depth and compared with commercial photodetectors,the validity and reliability of the quartz tuning fork photodetector were examined.By combining QCTF detector with new external cavity quantum cascade laser,a set of volatile organic detection system is built.In this paper,the infrared absorption spectra of volatile organic compounds in gasoline samples at different sites are detected.By combining the standard reference spectra with self-established interpolation algorithms and multiple linear regression algorithms,the relative content analysis and component assignment of major volatile organic compounds in different types of gasoline samples were realized,and the results were in good agreement with the results reported by other testing methods.In addition,the system is extended to the remote sensing detection of volatile organic compounds,and the fixed-wavelength detection mode is used to effectively suppress the turbulence effect of the atmosphere and volatile plumes.The effective identification and analysis of the mixed plumes of three volatile organic compounds,ether,acetone and ethanol,were achieved at wavelengths of 1150 cm-1,1217 cm-1 and 1250 cm-1,respectively.And the detection range is up to 40 meters,which lays a good foundation for applications such as hazardous chemical leakage monitoring and intelligent early warning in the fields of industrial process control and public safety maintenance.