共焦拉曼光谱对疏水基底上Mg(CH3COO)2液滴与CO2非均相反应动力学过程的观测

本文利用共焦拉曼光谱在球形液滴的表面和中心可聚焦两次的特性, 观测了不同RH(relative humidity, 相对湿度)下疏水基底上Mg(CH3COO)2液滴与CO2在液滴表面和中心的反应情况。结果表明, 反应生成的产物为碱式碳酸镁。当RH约73%时, 液滴表面和中心生成的产物的量差别不大; 当RH约65%时, 表面和中心的差别较RH约73%时明显; 而当RH降至约58%时, 表面和中心的差别则变得非常明显。由于Mg(CH3COO)2液滴在较低相对湿度下会形成胶态结构, 引起传质受阻, 从而使得CO2由液滴表面扩散到内部变得越来越困难, 最终导致液滴表面生成的产物比中心多。

Confocal Raman Observation on the Heterogeneous Reaction Kinetics of Magnesium Acetate Droplet on a Hydrophobic Substrate and Carbon Dioxide

Confocal Raman spectroscopy could focus on the surface and in the center of a spherical droplet respectively.Taking advantage of this property,the heterogeneous reaction of spherical Mg(CH3COO)2 droplets on a hydrophobic substrate and CO2 on the surface and in the center of the droplet were observed at different RH(relative humidity) by confocal Raman spectroscopy.The results showed that the reaction product is magnesium carbonate.When RH was ~73%,the amounts of the reaction product on the surface and in the center of the droplet were almost the same.While RH was ~65%,the amount of the product on the surface was apparently larger than that in the center.As the RH decreased to ~58%,the difference between surface and center became very obvious.Since Mg(CH3COO)2 droplet would form gel structure at low RH,the mass transfer in the droplet was depressed,and the diffusion of CO2 from the surface to the interior of the droplet would become more and more difficult with RH decrease,resulting in the amount of the reaction product on the surface larger than that in the center of the droplet.