First Evidence of Solvent Spillage under Subcritical Conditions in Aerogel Production
First Evidence of Solvent Spillage under Subcritical Conditions in Aerogel Production
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DOI：
10.1021/acs.iecr.8b00855
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发表时间：
2018-07-04
影响因子：
4.2
通讯作者：
Smimova, Irina
中科院分区：
文献类型：
--
作者：
Bueno, Alberto;Selmer, Ilka;Smimova, Irina
第一个证据的溶剂溢出在亚临界条件下气凝胶生产过程中。主要目的是了解高压釜加压过程中控制溶剂萃取动力学的基本现象。海藻酸盐，二氧化硅，和聚氨酯作为凝胶和乙醇，甲基乙基酮，和乙醇/水作为溶剂进行了研究。当CO2在凝胶溶剂中扩散时，存在液体溶剂的体积膨胀。这种膨胀的液体混合物从凝胶中溢出，并在高压釜底部作为单独的液相积聚。在高压釜加压开始和液体开始在高压釜中积聚的时刻之间观察到滞后时间。溶剂开始在高压釜底部积聚所需的时间由毛细管力和CO2-气相的饱和度控制，温度对其有重要影响。低的操作温度，从而在气相中的溶剂的低溶解度被认为是提高在亚临界条件下的溶剂去除的动力学的因素。
The first evidence of solvent spillage under subcritical conditions during aerogel production is presented. The main objective was to understand the underlying phenomena controlling the solvent extraction kinetics during autoclave pressurization. Alginate, silica, and polyurethane as gels and ethanol, methyl ethyl ketone, and ethanol/water as solvents were investigated. When CO2 diffuses in the gel solvent, there is a volume expansion of the liquid solvent. This expanded liquid mixture spills out of the gel and accumulates as a separate liquid phase at the bottom of the autoclave. A lag time was observed between the start of the autoclave pressurization and the moment in which liquid starts to accumulate in the autoclave. The time needed for the solvent to start accumulating at the bottom of the autoclave is controlled by capillary forces and the saturation of the CO2-gas phase, on which temperature has an important effect. Low operating temperature and thereby low solubility of the solvent in the gas phase is suggested as the factor that enhances the kinetics of solvent removal at subcritical conditions.