Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Environ Sci Technol. 2012 Oct 16;46(20):11112-8. doi: 10.1021/es302414v. Epub 2012 Sep 25.
Heterogeneous uptake of methylamine (MA), dimethylamine (DMA), and trimethylamine (TMA) onto citric acid and humic acid was investigated using a Knudsen cell reactor coupled to a quadrupole mass spectrometer at 298 K. Acid-base reactions between amines and carboxylic acids were confirmed. The observed uptake coefficients of MA, DMA, and TMA on citric acid at 298 K were measured to be 7.31 ± 1.13 × 10(-3), 6.65 ± 0.49 × 10(-3), and 5.82 ± 0.68 × 10(-3), respectively, and showed independence of sample mass. The observed uptake coefficients of MA, DMA, and TMA on humic acid at 298 K increased linearly with sample mass, and the true uptake coefficients of MA, DMA, and TMA were measured to be 1.26 ± 0.07 × 10(-5), 7.33 ± 0.40 × 10(-6), and 4.75 ± 0.15 × 10(-6), respectively. Citric acid, having stronger acidity, showed a higher reactivity than humic acid for a given amine; while the steric effect of amines was found to govern the reactivity between amines and citric acid or humic acid.
在 298 K 下，使用带有四极质谱仪的 Knudsen 细胞反应器研究了柠檬酸和腐殖酸对甲胺（MA）、二甲胺（DMA）和三甲胺（TMA）的异质吸收。证实了胺与羧酸之间的酸碱反应。在 298 K 下，测量了柠檬酸上 MA、DMA 和 TMA 的观察到的吸收系数分别为 7.31 ± 1.13×10(-3)、6.65 ± 0.49×10(-3)和 5.82 ± 0.68×10(-3)，并且与样品质量无关。在 298 K 下，柠檬酸上 MA、DMA 和 TMA 的观察到的吸收系数随样品质量线性增加，并且 MA、DMA 和 TMA 的真实吸收系数分别测量为 1.26 ± 0.07×10(-5)、7.33 ± 0.40×10(-6)和 4.75 ± 0.15×10(-6)。具有更强酸度的柠檬酸对于给定的胺显示出比腐殖酸更高的反应性；而胺的空间效应被发现控制着胺与柠檬酸或腐殖酸之间的反应性。
