Heterogeneous chemistry between PbSO4 and calcite microparticles using Raman microimaging.
Currently, the smelting activities of lead and zinc are the loudest sources of local pollution by emission in the troposphere of dust of micrometer size containing PbSO(4). As the particles evolve in the troposphere, their chemical and physical properties - and hence their characteristics such as toxicity - change by accumulation of atmospheric heterogeneous reactions. Calcite (CaCO(3)) represents a large part of the mineral fraction in tropospheric aerosols with aerodynamic diameters less than 10 microm. The calcite particles are expected to react with PbSO(4) particles. In an effort to model the chemical behaviour of PbSO(4) individual particles in the troposphere, we present the in situ Raman imaging results during the course of the reactions in a water droplet of PbSO(4) particles with a calcite microcrystal surface. The computer-microcontrolled XY scanning and Z focusing of confocal Raman imaging combined with multivariate curve resolution (MCR) of Raman images have resolved the severe spectral overlaps of the Raman spectra which are not resolved by the spatial resolution of the instrument ( approximately 1 microm(3)). The results pointed out the identification and the mapping of Pb(3)(CO(3))(2)(OH)(2), PbCO(3) and CaSO(4).2H(2)O (gypsum) on the calcite surface.
Falgayrac
Guillaume
G
Laboratoire de Spectrochimie IR et Raman, UMR-CNRS 8516, CERLA FR-CNRS 2416, Université de Lille I, F-59655 Villeneuve d'Ascq, Cedex, France.
Sobanska
Sobanska
S
Laureyns
Jacky
J
Brémard
Claude
C
D000393:Air Pollutants / Q000737:chemistry*; D002119:Calcium Carbonate / Q000737:chemistry*; D003952:Diagnostic Imaging / Q000379:methods; D004391:Dust / Q000032:analysis*; D007854:Lead / Q000737:chemistry*; D008956:Models, Chemical; D010316:Particle Size
D000393:Air Pollutants; D004391:Dust; D007854:Lead; C032722:lead sulfate; D002119:Calcium Carbonate