Comparative Study On The Extraction Methods Of Metal Elements In PM_2.5

Airborne fine particulate matte can directly affect the climate and environment byscattering and absorbing solar radiation. Among them, the fine particulate matter (PM2.5)can easily float and spread in atmospheric over a long period of time because of its smallsize, light weight and large quantity. Metal elements As an important part of PM2.5canenter into human body and result in functional disorder irreversible damage throughrespiration. PM2.5is greatly harmful to human health, therefore, it has become one of thehot research topic in recent years.The extraction rate of each extraction methods cannot be obtained because eachcomponent contents of PM2.5in the atmospheric environment are extremely unstable.Therefore it is difficult to measure the applicability, the advantages and disadvantages ofthe extraction methods of metal elements. In this paper, the national standard soil samplesof known metal content are resuspended through PM2.5suspension box and collected byTeflon membrane and QFF, and then six kinds of methods are used to extract Ca、Mg、Na、K in PM2.5on filter membrane and its extraction rate is calculated. The results showthat the metal elements in PM2.5on QFF are easier to be extracted than on Teflonmembrane filter; the extraction effects of various kinds of acid extraction are better thanwater extraction; HClO4method is a method that has highest extraction rate of metalelements in PM2.5on Teflon membrane; In addition to the literature method to extract Ca,HF method has the best extraction effect on extracting metal elements in PM2.5on QFF.Based on above conclusions, this paper studies extraction effects of Mg、Na、K、Zn、Cu、Pb on Teflon filter membrane by means of six different combinations of the five kindsof acid currently used to the digestion of metal elements in PM2.5, in order to get the bestdigestion method of PM2.5metal elements. Then this study explores further optimizationof the method by using H2O2combined with the nature of the hydrolytic acid, whichmakes the extraction of the heavy metal more efficient, in order to test the applicability ofthe optimal extraction method obtained in laboratory by applying to the atmospheric environment.Results show that the total order of six kinds of metal extraction effect extracted bysix kinds of atmospheric particulate matter digestion method is: HF+HClO4method>HCl+HClO4method>HF method>HClO4method> H2O2method> HCl method.Among these methods, HF+HClO4method is the best method to extract Mg、Na、K、Zn、Cu、Pb on Teflon filter membrane; Extraction effects of each metal element aredifferent by combined use of different acid and HNO3. HClO4makes the most significantcontribution to the extraction of the three metal elements, HF takes the second place, HClis the worst; H2O2only has a good effect on the extraction of Zn; The increase of typesand quantity of acid can improve the effect of the extraction of metal elements, the mixeduse of acid of different mechanism is more favorable to extraction of metal elements inPM2.5.The optimization method obtained by adding H2O2, especially HF+HClO4method,to a certain extent, can eliminate the interference of detection instrument caused by otheracid at the same time of improving the efficiency of the metal extraction, therefore, it isthe best method to extract metal element in indoor PM2.5. This method also applies to theatmospheric environment tested by the outdoor sampling experiment. Therefore, it canalso be used for total analysis on metal element in PM2.5in the future.