title: Heterogeneous reactions of SO2 with HOCl and HOBr on ice surfaces.
abstract: The heterogeneous reactions of SO2 + HOX (X = Cl or Br) --> products on ice surfaces at low temperature have been investigated in a flow reactor coupled with a differentially pumped quadrupole mass spectrometer. Pseudo-first-order loss of SO2 over the ice surfaces has been measured under the conditions of concurrent HOX flow. The initial uptake coefficient of SO2 reaction with HOX has been determined as a function of HOX surface coverage, theta(HOX), on the ice. The initial uptake coefficients increase as the HOX coverage increases. The uptake coefficient can be expressed as gamma(t) = k(h)theta(HOX), where k(h) is an overall rate constant of SO2 + HOCl, which was determined to be (2.3 +/- 0.6) x 10(-19) and (1.7 +/- 0.5) x 10(-19) molecules(-1) x cm2 at 190 and 210 K, and k(h) of SO2 + HOBr is (6.1 +/- 2.0) x 10(-18) molecules(-1) x cm2 at 190 K. theta( HOX) is in the range 8.1 x 10(13)-9.1 x 10(14) molecules x cm(-2). The kinetic results of the heterogeneous reaction of SO2 + HOX on ice surface are interpreted using the Eley-Rideal mechanism. The activation energy of the heterogeneous reaction of SO2 with HOCl on ice surface was determined to be about -37 +/- 10 kJ/mol in the 190-238 K range.
authors.affiliation: Wadsworth Center, New York State Health Department and Department of Environmental Health Sciences, State University of New York at Albany, P.O. Box 509, Albany, New York 12201-0509, USA.
authors.forename: Ronghua
authors.initials: R
authors.lastname: Jin
authors.forename: Liang T
authors.initials: LT
authors.lastname: Chu
mesh_terms: D001959:Bromates / Q000737:chemistry*; D006997:Hypochlorous Acid / Q000737:chemistry*; D007053:Ice; D007700:Kinetics; D008956:Models, Chemical; D010084:Oxidation-Reduction; D013458:Sulfur Dioxide / Q000737:chemistry*; D013499:Surface Properties; D013816:Thermodynamics
chemical_list: D001959:Bromates; D007053:Ice; D013458:Sulfur Dioxide; D006997:Hypochlorous Acid; C027664:hypobromous acid