Direct Emission of I2 Molecule and IO Radical from the Heterogeneous Reactions of Gaseous Ozone with Aqueous Potassium Iodide Solution

详细信息    查看全文

• 作者：Yosuke Sakamoto ; Akihiro Yabushita ; Masahiro Kawasaki ; Shinichi Enami
• 刊名：Journal of Physical Chemistry A
• 出版年：2009
• 出版时间：July 9, 2009
• 年：2009
• 卷：113
• 期：27
• 页码：7707-7713
• 全文大小：173K
• 年卷期：v.113,no.27(July 9, 2009)
• ISSN：1520-5215

文摘

Recent studies indicated that gaseous halogens mediate key tropospheric chemical processes. The inclusion of halogen-ozone chemistry in atmospheric box models actually closes the 50% gap between estimated and measured ozone losses in the marine boundary layer. The additional source of gaseous halogens is deemed to involve previously unaccounted for reactions of O₃(g) with sea surface water and marine aerosols. Here, we report that molecular iodine, I₂(g), and iodine monoxide radical, IO(g), are released ([I₂(g)] > 100[IO(g)]) during the heterogeneous reaction of gaseous ozone, O₃(g), with aqueous potassium iodide, KI(aq). It was found that (1) the amounts of I₂(g) and IO(g) produced are directly proportional to [KI(aq)] up to 5 mM and (2) IO(g) yields are independent of bulk pH between 2 and 11, whereas I₂(g) production is markedly enhanced at pH < 4. We propose that O₃(g) reacts with I⁻ at the air/water interface to produce I₂(g) and IO(g) via HOI and IOOO⁻ intermediates, respectively.