Effect of residence time and different micro-mixers on supercritical CO2 extraction of vanillin from aqueous solution

IF 4.4 3区工程技术 Q2 CHEMISTRY, PHYSICAL

Journal of Supercritical Fluids Pub Date : 2025-09-05 DOI:10.1016/j.supflu.2025.106779

Tatsuya Fujii, Yuko Sakurai, Shin-ichiro Kawasaki, Takayuki Ishizaka

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Abstract

This study investigated the effect of mixer type and residence time on continuous supercritical carbon dioxide extraction of vanillin from an aqueous solution at 40 °C, 20 MPa. Average residence time was varied by changing the length of the extraction tubing downstream of a tee-type mixer with an inner diameter of 0.33 mm. In the short residence time region, the effect of different micro-mixer geometries on extraction efficiency was also examined. A two-film mass transfer model was applied to the experimental data to estimate the volumetric mass transfer coefficient. A modified version of the model that considers additional extraction in the separation zone after the extraction tube provided better agreement with the experimental results. The obtained volumetric mass transfer coefficient was on the order of 1 s⁻¹, which falls within the range of values reported for slug flow extraction of vanillin using toluene as the solvent. Extraction efficiencies were also compared across mixers with different internal geometries at fixed tubing residence time. The results showed that smaller internal diameters in the tee-type mixer lead to higher extraction efficiency. High-speed filming revealed that such conditions produced slug-like flows with dispersed droplets, contributing to a larger interfacial area between the CO₂ and aqueous phases. Furthermore, the swirl-type mixer exhibited higher extraction performance than that of the tee-type mixer with the same inner diameter (0.8 mm).

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停留时间及不同微混合器对超临界CO2萃取水溶液中香兰素的影响

本研究考察了混合器类型和停留时间对40℃，20 MPa连续超临界二氧化碳萃取水溶液中香兰素的影响。在内径为0.33 mm的三叉混合器下游，通过改变萃取管的长度来改变平均停留时间。在短停留时间内，考察了不同微混合器几何形状对萃取效率的影响。采用双膜传质模型对实验数据进行了体积传质系数的估计。考虑萃取管后分离区附加萃取的修正模型与实验结果吻合较好。得到的体积传质系数约为1 s−1，在以甲苯为溶剂的段塞流萃取香兰素的范围内。在固定的油管停留时间下，还比较了不同内部几何形状的混合器的萃取效率。结果表明，三字型混合器内径越小，萃取效率越高。高速拍摄显示，这种条件下会产生段塞状流动，液滴分散，导致二氧化碳和水相之间的界面面积更大。此外，在相同内径（0.8 mm）下，旋流混合器的萃取性能优于三字型混合器。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of Supercritical Fluids 工程技术-工程：化工

CiteScore

7.60

自引率

10.30%

发文量

236

审稿时长

56 days

期刊介绍： The Journal of Supercritical Fluids is an international journal devoted to the fundamental and applied aspects of supercritical fluids and processes. Its aim is to provide a focused platform for academic and industrial researchers to report their findings and to have ready access to the advances in this rapidly growing field. Its coverage is multidisciplinary and includes both basic and applied topics. Thermodynamics and phase equilibria, reaction kinetics and rate processes, thermal and transport properties, and all topics related to processing such as separations (extraction, fractionation, purification, chromatography) nucleation and impregnation are within the scope. Accounts of specific engineering applications such as those encountered in food, fuel, natural products, minerals, pharmaceuticals and polymer industries are included. Topics related to high pressure equipment design, analytical techniques, sensors, and process control methodologies are also within the scope of the journal.