民用燃煤排放颗粒物中金属元素组成及单颗粒分析

借助稀释通道采样系统,采集了5种民用煤(3种块煤、1种蜂窝煤和1种煤球)燃烧排放的PM2.5和单颗粒样品.利用ICP-MS分析了PM2.5中16种金属元素(Mg、Al和K 3种轻金属;V、Cr、Mn、Fe、Co、Ni、Cu、As、Rb、Sr、Cd、Ba和Bi共13种重金属)的含量,并运用TEM和SEM-EDX研究了燃煤...

Emission characteristics of metals in particles emitted from residential coal burning and individual particle analysis

A dilution sampling system was used to collect PM_2.5 samples and individual particles emitted from the combustion of five typical residential coals(three raw coals,one honeycomb coal,and one coal ball).The concentrations of 16 metals(3 light metals as Mg,Al,and K;and 13 heavy metals including V,Cr,Mn,Fe,Co,Ni,Cu,As,Rb,Sr,Cd,Ba,and Bi)in PM_2.5 were measured by an inductively coupled plasma mass spectrometry(ICP-MS).Individual particles were observed by transmission electron microscopy(TEM)and scanning electron microscopy with energy-dispersive X-ray spectrometry(SEM-EDX).Results showed that the concentration of metals in PM2.5 emitted from honeycomb coal(29.7%)and coal ball(33.0%)burning were higher than those from raw coal(8.9%-23.7%)burning.Al dominated among the three light metals,accounting for 45.0% to 57.8%.Fe,Ba,and As were the dominant heavy metals,accounting for 69.5%to 78.4% of the 13 heavy metals.Single particle analysis showed that the typical particle morphologies of raw coal combustion were soot aggregates,spherical particles,and particles with irregular shapes.Spherical particles dominated the particles from honeycomb coal and coal ball combustion.The mean particle sizes of honeycomb coal combustion were 0.26,0.17,and 0.28μm in different combustion stages(the early stage,the mid stage,and the later stage),and the average particle sizes of coal ball combustion were 0.11,0.47,and 0.06μm,respectively.Compared with honeycomb coal and coal ball,the average particle size of raw coal in smaller fire combustion was higher,and the average particle sizes of the three combustion stages were 0.38,0.45,and 0.36μm.The results showed that the aspect ratio of particles emitted from raw coal combustion was higher,and the circularity factor was lower than those of the particles emitted from honeycomb coal and coal ball.The aspect ratio of 90% of the particles emitted from raw coal combustion was mainly between 1.0 and 2.0,and 95% of the particles emitted from honeycomb coal and coal ball mainly had an aspect ratio ranging from 1.0 to 1.5.The average circularity factors of particles in different stages of raw coal combustion were 0.60,0.65,and 0.75.The values were around 0.90 and 0.80,respectively for honeycomb coal and coal ball during the three different combustion stages.According to EDX analysis results,the dominant elements in soot aggregates were C,O,and Si.The contents of Al were also obvious in the particles with other morphologies,which was consistent with the results of bulk analysis.