School of Environmental Science and Engineering, Shandong University, Qingdao 266237, China.
Atmospheric Chemistry Department (ACD), Leibniz-Institute for Tropospheric Research (TROPOS), Permoserstraße 15, Leipzig 04318, Germany.
J Phys Chem A. 2022 Sep 15;126(36):6244-6252. doi: 10.1021/acs.jpca.2c03044. Epub 2022 Sep 4.
Tartaric acid and mucic acid are dicarboxylic acids (DCAs), a substance class often found in atmospheric aerosols and cloud droplets. The hydroxyl radical (OH)-induced oxidation in the aqueous phase is known to be an important loss process of organic compounds such as DCAs. However, the study of OH kinetics of DCAs in the aqueous phase is still incomplete. In the present study, the rate constants of the OH reactions of tartaric acid and mucic acid in the aqueous phase were determined by the thiocyanate competition kinetics method as a function of temperature and pH. The following T-dependent Arrhenius expressions (in units of L mol s) were first derived for the OH reactions with tartaric acid─(T, HA) = (3.3 ± 0.1) × 10 exp[(-1350 ± 110 K)/T], (T, HA) = (3.6 ± 0.1) × 10 exp[(-580 ± 110 K)/T], and (T, A) = (3.3 ± 0.1) × 10 exp[(-1190 ± 170 K)/T]─as well as mucic acid─(T, HA) = (2.2 ± 0.1) × 10 exp[(-1140 ± 150 K)/T], (T, HA) = (4.8 ± 0.1) × 10 exp[(-1280 ± 170 K)/T], and (T, A) = (2.1 ± 0.1) × 10 exp[(-970 ± 70 K)/T]. A general trend of the OH rate constant is found as . The pH- and temperature-dependent rate constants of the OH radical reactions allow an accurate description of the source and sink processes in the tropospheric aqueous phase.
酒石酸和粘酸是二羧酸（DCAs），是大气气溶胶和云滴中常见的物质类别。已知羟基自由基（OH）在水相中的诱导氧化是 DCA 等有机化合物的重要损失过程。然而，水相中二羧酸的 OH 动力学研究仍不完善。在本研究中，通过硫氰酸盐竞争动力学方法，确定了水相中亚酒石酸和粘酸与 OH 反应的速率常数随温度和 pH 的变化。首先，导出了以下与酒石酸的 T 依赖性 Arrhenius 表达式（单位为 L mol s）：（T，HA）=（3.3±0.1）×10 exp[（-1350±110 K）/T]，（T，HA）=（3.6±0.1）×10 exp[（-580±110 K）/T]，和（T，A）=（3.3±0.1）×10 exp[（-1190±170 K）/T]，以及粘酸：（T，HA）=（2.2±0.1）×10 exp[（-1140±150 K）/T]，（T，HA）=（4.8±0.1）×10 exp[（-1280±170 K）/T]，和（T，A）=（2.1±0.1）×10 exp[（-970±70 K）/T]。发现 OH 速率常数的一般趋势为。OH 自由基反应的 pH 和温度依赖性速率常数可以准确描述对流层水相中的源汇过程。
