amorphous protein
; bovine serum albumin
; organic compound
; ozone
; protein
; unclassified drug
; aerosol
; article
; atmosphere
; diffusion
; humidity
; oxidation
; priority journal
; temperature sensitive clone
; wettability
; Aerosols
; Air Pollutants
; Animals
; Atmosphere
; Cattle
; Diffusion
; Gases
; Humans
; Humidity
; Models, Chemical
; Ozone
; Particulate Matter
; Public Health
; Serum Albumin, Bovine
; Viscosity
英文摘要:
Organic substances can adopt an amorphous solid or semisolid state, influencing the rate of heterogeneous reactions and multi-phase processes in atmospheric aerosols. Here we demonstrate how molecular diffusion in the condensed phase affects the gas uptake and chemical transformation of semisolid organic particles. Flow tube experiments show that the ozone uptake and oxidative aging of amorphous protein is kinetically limited by bulk diffusion. The reactive gas uptake exhibits a pronounced increase with relative humidity, which can be explained by a decrease of viscosity and increase of diffusivity due to hygroscopic water uptake transforming the amorphous organic matrix from a glassy to a semisolid state (moisture-induced phase transition). The reaction rate depends on the condensed phase diffusion coefficients of both the oxidant and the organic reactant molecules, which can be described by a kinetic multilayer flux model but not by the traditional resistor model approach of multiphase chemistry. The chemical lifetime of reactive compounds in atmospheric particles can increase from seconds to days as the rate of diffusion in semisolid phases can decrease by multiple orders of magnitude in response to low temperature or low relative humidity. The findings demonstrate that the occurrence and properties of amorphous semisolid phases challenge traditional views and require advanced formalisms for the description of organic particle formation and transformation in atmospheric models of aerosol effects on air quality, public health, and climate.
Shiraiwa, M., Biogeochemistry Department, Max Planck Institute for Chemistry, P.O. Box 3060, 55128 Mainz, Germany; Ammann, M., Laboratory of Radiochemistry and Environmental Chemistry, Paul Scherrer Institut, CH-5232 Villigen, Switzerland; Koop, T., Faculty of Chemistry, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany; Pöschl, U., Biogeochemistry Department, Max Planck Institute for Chemistry, P.O. Box 3060, 55128 Mainz, Germany
Recommended Citation:
Shiraiwa M.,Ammann M.,Koop T.,et al. Gas uptake and chemical aging of semisolid organic aerosol particles[J]. Proceedings of the National Academy of Sciences of the United States of America,2011-01-01,108(27)