Heterogeneous microchemistry between CdSO<sub>4</sub> and CaCO<sub>3</sub> particles under humidity and liquid water - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Journal of Hazardous Materials Année : 2013

Heterogeneous microchemistry between CdSO4 and CaCO3 particles under humidity and liquid water

Résumé

Laboratory experiments using in situ Raman imaging combined with ex situ TOF-S-SIMS demonstrate the behavior of CdSO4*8/3H2O microparticles in contact with { 1014 } CaCO3 (calcite) surface under three different experimental conditions representative of unpolluted atmosphere. The contact of CdSO4*8/3H2O particles with CaCO3 surface in humid air (RH ∼ 40-80%) does not induce any chemical reaction. In contrast, the condensation of a water drop on CdSO4*8/3H2O/CaCO3 interface causes the free dissolution of CdSO4*8/3H2O particle in the drop. A CdSO4*8/3H2O microcrystal is reformed after gentle drying with a CdSO4*H2O coating of the CaCO3 surface. The TOF-S-SIMS image of the CaCO3 surface provides evidence of a thin layer corresponding probably to insoluble coating of CdCO3 (otavite) or CdxCa1xCO3 solid solution at the liquid-solid interface. This layer armours the CaCO3 from further dissolution and stops the reaction. The deposition of CdSO4*8/3H2O particle in water drop previously in contact with CaCO3 for a long time generates CdCO3 small rhombohedral crystals while gentle drying provokes the crystallization of bar shape crystals of CaSO4*2H2O (gypsum). These laboratory results provide valuable chemical prediction for a possible fate of cadmium rich particles emitted in the atmosphere and thus, can contribute to realistic assessment of human exposure to Cd hazard.

Dates et versions

hal-00796842 , version 1 (05-03-2013)

Identifiants

Citer

G. Falgayrac, S. Sobanska, C. Brémard. Heterogeneous microchemistry between CdSO4 and CaCO3 particles under humidity and liquid water. Journal of Hazardous Materials, 2013, 248-249, pp.415 - 423. ⟨10.1016/j.jhazmat.2013.01.029⟩. ⟨hal-00796842⟩
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