Study On Airborne Heavy Metals Sampling System For Atomic Fluorescence Spectrometry

Air pollution is one of the common concerns in the world.Some of the heavy metals carried by small particles in the atmosphere have a very serious impact on human health.At present,the detection and analysis of airborne heavy metals are still in the laboratory stage.It is necessary to design an enrichment sampling and pretreatment system that can be used for online monitoring of airborne heavy metals.Compared with other common atomic analysis instruments,atomic fluorescence spectrometer has the advantages of simple structure,high sensitivity,wide linear range and simultaneous detection of many kinds of elements.Therefore,on the basis of the self-built atomic fluorescence spectrometer,a rotating type airborne heavy metal enrichment sampling and pretreatment system was designed.The main feature of the system lies in its high degree of automation and high integration,which can be used in conjunction with atomic fluorescence spectrometer to realize on-line monitoring of heavy metals in the atmosphere.The main contents of this thesis are as follows:(1)We introduced the main sources,existing forms and biological hazards of heavy metals in the atmosphere.We compared commonly used methods for detecting heavy metals,the means and methods for measuring airborne heavy metals both at home and abroad.An atomic fluorescence instrument with high sensitivity,wide linear range and low cost was selected as a measuring instrument for metal elements.According to the principle and structure characteristics of the atomic fluorescence spectrometer,we put forward some requirements on the structure and function of airborne heavy metal concentration sampling and pretreatment system,so as to realize online monitoring for airborne heavy metals.(2)We designed a kind of airborne heavy metal sampling system for automatic enrichment sampling and digestion of atmospheric samples for seven consecutive days.We estimated and verified the possible deviations in the system,and designed algorithm which would decrease the deviations.In order to realize full automation of online monitoring system for airborne heavy metals,we also designed the sample transmission interface and the communication interface between airborne heavy metal sampling device and atomic fluorescence spectrometer.(3)We debugged the airborne heavy metal online monitoring system,and evaluated performance of the instrument.We produced standard solutions of different concentrations of arsenic,cadmium,mercury,and lead,which instead of the digestion solution in the digestion module.Then,the standard liquid concentration of the corresponding specific element was measured several times by airborne heavy metal analyzer.Based on the measured data,we evaluated the performance of the instrument.By calculating and analyzing the error of airborne heavy metal analyzer,the main source of error is obtained.