Infoscience

Journal article

Heterogeneous kinetics of the uptake of HOBr on solid alkali metal halides at ambient temperature

Bromine contg. compds. are thought to play an important role in the O3 destruction in various regions of the atm. Recent studies of atm. Br chem. suggest that HOBr is one of the important Br compds. The rapid photolysis of HOBr in daytime releases Br atoms and OH radicals, which causes ozone destruction. In this study, the reactivity of HOBr with solid alkali metal halides is reported which affords insights into the importance of heterogeneous reactions of HOBr with salt, which in the atm. act as substrate particles for the reactions. The heterogeneous reactions of HOBr with solid cryst. NaCl [HOBr(g) + NaCl(s) -> BrCl(g) + NaOH(s)] and KBr [HOBr(g) + KBr(s) -> Br2(g) + KOH(s)] substrates at ambient temp. have been investigated using a Teflon coated Knudsen cell reactor. Powder, grain, and spray-deposited salt substrates were used for the measurement of the HOBr reactivity. The obsd. uptake probability depends on the total external surface area of the salt substrates. For NaCl substrates, Br2 and BrCl are obsd. as products; for KBr substrates, Br2 is obsd. as the sole product. In both cases, a dependence of the initial uptake probability g0 on HOBr flow rate has been obsd. The initial uptake is large at low flow rate and 10 times smaller at high flow rate. Values of g0 ? (6.5 +- 2.5) * 10-3 for NaCl and g0 ? 0.18 +- 0.04 for KBr are obtained under our exptl. conditions of limiting low flow rates akin to atm. conditions. The prodn. of Br2 is obsd. even for HOBr interacting on solid NaNO3, a non-halogen contg. substrate. The yield measurements imply that a HOBr self-reaction occurs on salt surfaces according to 2HOBr -> Br2 + H2O + 1/2O2. The decrease in Br2 yield with increasing HOBr flow rate from 100 to 50% indicates that a competition between the heterogeneous reaction of HOBr with NaCl or KBr and the self-reaction of HOBr takes place on the solid salt surface under lab. exptl. conditions. The decrease of g0 with time indicates that approx. 5-10% of the Br atoms on a KBr surface interact with HOBr.

    Keywords: 7726-95-6 (Bromine) Role: FMU (Formation ; unclassified) ; FORM (Formation ; nonpreparative) (heterogeneous kinetics of the uptake of HOBr on solid alkali metal halides at ambient temp. to simulate reactions on salt substrate particles in the atm. which co ; hypobromous acid reaction salt ozone atm

    Note:

    Copyright 2003 ACS

    CAPLUS

    AN 1998:338722

    CAN 129:125051

    53-10

    Mineralogical and Geological Chemistry

    59

    Research Center for Advanced Science and Technology,University of Tokyo,Tokyo,Japan. FIELD URL:

    Journal

    JPCAFH

    written in English.

    Atmosphere (heterogeneous kinetics of the uptake of HOBr on solid alkali metal halides at ambient temp. to simulate reactions on salt substrate particles in the atm. which contribute to ozone destruction); Stratosphere (volcanic aerosol; heterogeneous kinetics of the uptake of HOBr on solid alkali metal halides at ambient temp. to simulate reactions on salt substrate particles in the atm. which contribute to ozone destruction)

    1) Barrie, L; Nature 1988, 334, 138|2) Bottenheim, J; J Geophys Res 1988, 95, 18555|3) Hausmann, M; J Geophys Res 1994, 99, 25399|4) Li, S; J Geophys Res 1994, 99, 25415|5) Solberg, S; J Atmos Chem 1996, 23, 301|6) Impey, G; J Geophys Res 1997, 102, 16005|7) Schroeder, W; En iron Sci Technol 1974, 8, 756|8) Finlayson-Pitts, B; Nature 1983, 306, 676|9) George, C; J Phys Chem 1994, 98, 8780|10) Vogt, R; J Phys Chem 1994, 98, 3747|11) Fenter, F; J Phys Chem 1994, 98, 9801|12) Timonen, R; J Phys Chem 1995, 99, 9509|13) Leu, M; J Phys Chem 1995, 99, 13203|14) Fenter, F; J Phys Chem 1996, 100, 1008|15) Allen, H; J Phys Chem 1996, 100, 6371|16) Caloz, F; J Phys Chem 1996, 100, 7494|17) Peters, S; J Phys Chem 1996, 100, 14093|18) Beichert, P; J Phys Chem 1996, 100, 15218|19) Laux, J; J Phys Chem 1996, 100, 19891|20) Behnke, W; J Geophys Res 1997, 102, 3795|21) Seisel, S; J Geophys Res Lett 1997, 24, 2757|22) Fan, S; Nature 1992, 359, 522|23) Sander, R; J Geophys Res 1995, 101, 9121|24) Vogt, R; Nature 1996, 383, 327|25) Tang, T; Geophys Res Lett 1996, 23, 2633|26) McGrath, M; J Phys Chem 1994, 98, 4773|27) Orlando, J; J Phys Chem 1995, 99, 1143|28) Lock, M; J Phys Chem 1996, 100, 7972|29) Francisco, J; J Phys Chem 1996, 100, 9250|30) Abbatt, J; Geophys Res Lett 1994, 21, 665|31) Allanic, A; J Geophys Res 1997, 102, 23529|32) Abbatt, J; J Geophys Res 1995, 100, 14009|33) Kirchner, U; Ber Bunsen-Ges Phys Chem 1997, 101, 975|34) Woods, D; Science 1985, 230, 170|35) Cahill, T; J Geophys Res 1992, 97, 14513|36) Parungo, F; J Geophys Res 1992, 97, 15867|37) Lowenthal, D; Geophys Res Lett 1993, 20, 693|38) Shaw, G; J Geophys Res 1991, 96, 22369|39) Caloz, F; Re Sci Instrum 1997, 68, 3172|40) Fenter, F; Re Sci Instrum 1997, 68, 3180|41) Keyser, L; J Phys Chem 1991, 95, 5496|42) Chu, L; J Phys Chem 1993, 97, 12798|43) Chu, L; J Phys Chem 1993, 97, 7779|44) Keyser, L; J Phys Chem 1993, 97, 2800|45) Keyser, L; J Colloid Interface Sci 1993, 155, 137|46) Wheeler, A; Ad Catal 1951, 3, 249|47) Aris, R; The Mathematical Theory of Diffusion and Reaction in Permeable Catalysis 1975, I|48) Dahneke, B; Theory of Dispersed Multiphase Flow 1983, 97|49) Fitzgerald, J; Atmos En iron 1991, 25A, 533|50) Hanson, D; J Geophys Res 1996, 101, 9063|51) Folsh, S; Surf Sci 1992, 264, 65|52) Tepper, P; J Vac Sci Technol 1989, B7, 1212|53) Folsh, S; Surf Sci 1991, 247, 269|55) Michelangeli, D; Geophys Res Lett 1991, 18, 673|56) Demore, W; Chemical Kinetics and Photochemical Data for Use in Stratospheric Modeling 1997

    Reference

    Record created on 2011-02-01, modified on 2016-08-09

Fulltext

Related material