Release of gas-phase halogens from sodium halide substrates: heterogeneous oxidation of frozen solutions and desiccated salts by hydroxyl radicals
Release of gas-phase halogens from sodium halide substrates: heterogeneous oxidation of frozen solutions and desiccated salts by hydroxyl radicals
复制标题
从卤化钠基质中释放气相卤素：羟基自由基对冷冻溶液和干燥盐的非均相氧化
DOI：
10.1088/1748-9326/3/4/045007
复制
发表时间：
2008
影响因子：
6.7
通讯作者：
J. Abbatt
中科院分区：
文献类型：
--
作者：
S. Sjostedt;J. Abbatt
由于需要确定卤素从海冰和海洋气溶胶基质中初始释放的机制，在涂覆壁流动管中利用化学电离质谱仪进行了气相分析，研究了OH自由基与各种含卤化物表面的相互作用。所研究的盐分别是杂质含量分别为0.01%和0.002%的溴-−和碘-−的氯化钠，以及氯-−/溴-−海水比的氯化钠/溴化钠混合物。表面是干燥的盐、暴露在较高相对湿度下的干燥盐和冷冻溶液。在所有情况下，都形成了气相Br2和BrCl2，Br2产率(定义为产生的卤素与损失的OH的摩尔比)大于0.2，BrCl产率约为0.01。首次观察到含碘卤素(特别是IBR)的异相释放，其产率与BrCL相当。我们注意到，pH中性的冷冻溶液表现出卤素的释放，尽管酸性冷冻溶液的产率更高。
Motivated by the need to determine the mechanism of the initial release of halogens from sea ice and marine aerosol substrates, a study of the interactions of OH radicals with a variety of halide-containing surfaces has been performed in a coated-wall flow tube using chemical ionization mass spectrometry for gas-phase analysis. The salts studied were NaCl with 0.01% and 0.002% impurities of Br− and I− respectively, and NaCl/NaBr mixtures with Cl−/Br− seawater ratios. The surfaces were desiccated salts, desiccated salts exposed to elevated relative humidity, and frozen solutions. In all cases, gas-phase Br2 and BrCl were formed, with the Br2 yield (defined as a molar ratio of halogen produced to OH lost) larger than 0.2 and the BrCl yield as roughly 0.01. For the first time, an observation of heterogeneous release of iodine-containing halogens (in particular IBr) was made with yields comparable to those of BrCl. We note that pH neutral frozen solutions demonstrated halogen release, although the yields were higher for acidic frozen solutions.