title: Internal structure, hygroscopic and reactive properties of mixed sodium methanesulfonate-sodium chloride particles.
abstract: Internal structures, hygroscopic properties and heterogeneous reactivity of mixed CH(3)SO(3)Na/NaCl particles were investigated using a combination of computer modeling and experimental approaches. Surfactant properties of CH(3)SO(3)(-) ions and their surface accumulation in wet, deliquesced particles were assessed using molecular dynamics (MD) simulations and surface tension measurements. Internal structures of dry CH(3)SO(3)Na/NaCl particles were investigated using scanning electron microscopy (SEM) assisted with X-ray microanalysis mapping, and time-of-flight secondary ion mass spectrometry (TOF-SIMS). The combination of these techniques shows that dry CH(3)SO(3)Na/NaCl particles are composed of a NaCl core surrounded by a CH(3)SO(3)Na shell. Hygroscopic growth, deliquescence and efflorescence phase transitions of mixed CH(3)SO(3)Na/NaCl particles were determined and compared to those of pure NaCl particles. These results indicate that particles undergo a two step deliquescence transition: first at ∼69% relative humidity (RH) the CH(3)SO(3)Na shell takes up water, and then at ∼75% RH the NaCl core deliquesces. Reactive uptake coefficients for the particle-HNO(3) heterogeneous reaction were determined at different CH(3)SO(3)Na/NaCl mixing ratios and RH. The net reaction probability decreased notably with increasing CH(3)SO(3)Na and at lower RH.
authors.affiliation: William R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P. O. Box 999, MSIN K8-88, Richland, WA 99352, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
authors.forename: B
authors.initials: B
authors.lastname: Minofar
authors.forename: Y
authors.initials: Y
authors.lastname: Desyaterik
authors.forename: E
authors.initials: E
authors.lastname: Dames
authors.forename: Z
authors.initials: Z
authors.lastname: Zhu
authors.forename: J P
authors.initials: JP
authors.lastname: Cain
authors.forename: R J
authors.initials: RJ
authors.lastname: Hopkins
authors.forename: M K
authors.initials: MK
authors.lastname: Gilles
authors.forename: H
authors.initials: H
authors.lastname: Wang
authors.forename: P
authors.initials: P
authors.lastname: Jungwirth
authors.forename: A
authors.initials: A
authors.lastname: Laskin
mesh_terms: D007700:Kinetics; D008698:Mesylates / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D017942:Nitric Acid / Q000737:chemistry; D012965:Sodium Chloride / Q000737:chemistry*; D013500:Surface Tension
chemical_list: D008698:Mesylates; C045880:methanesulfonic acid; D017942:Nitric Acid; D012965:Sodium Chloride