Countercurrent laminar microflow for highly efficient solvent extraction
Countercurrent laminar microflow for highly efficient solvent extraction
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DOI：
10.1002/anie.200600122
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发表时间：
2007-01-01
影响因子：
16.6
通讯作者：
Kitamori, Takehiko
中科院分区：
文献类型：
--
作者：
Aota, Arata;Nonaka, Masaki;Kitamori, Takehiko
逆流通常用于各种化学领域。在传统的宏观装置中，由于界面处的高剪切应力而破裂的液滴伴随着逆流流动。从允许更好地设计和控制微通道中的化学过程的角度来看，平行逆流层流是更可取的。本文报道了微通道中低雷诺数Re （Re< 2.3）条件下的逆流层流微流动。为了产生水相和有机相的逆流，我们选择性地用疏水性基团修饰微通道壁的下半部分，而上半部分保持亲水性。研究了两相的流量比，并验证了逆流流的宽工作范围。将逆流法应用于溶剂萃取工艺。传统的采用共流多相流或液滴的微尺度萃取可以达到仅为1的理论板数，而采用逆流微流的萃取可以达到更高的理论板数。我们发现在水-甲苯逆流微流中提取钴络合物的理论板数为4.6。基于压力驱动微流的微尺度技术研究进展迅速。[1-7]利用微空间的特性，可以通过压力驱动流动形成非混相并联共流微流。由于微空间内的流动具有低Re的特征，共流微流动可以看作层流。同时微流网络是集成微化学过程的有效工具，因为在层流状态下，不混相的顺序接触和分离可以自由地设计。通过这种方式，我们可以将各种微操作（MUO）组合在一起
Countercurrent flows are commonly used in various chemical fields. In conventional macroscale devices, countercurrent flows are accompanied by droplets from breakup due to high shear stress at the interface. Parallel countercurrent laminar flows are more desirable from the viewpoint of allowing better design and control of chemical processes in a microchannel. Herein, we report countercurrent laminar microflow under conditions that give a low Reynolds number Re (Re< 2.3) in a microchannel. To produce the countercurrent flow of aqueous and organic phases, we selectively modified the lower half of a microchannel wall with a hydrophobic group while the upper half was kept hydrophilic. The flow-rate ratio between the two phases was investigated and a wide operational range for the countercurrent flow was verified. The countercurrent flow was applied to a solvent-extraction process. While conventional microscale extractions with cocurrent multiphase flow or droplets can reach a theoretical plate number of only unity, a higher theoretical plate number is expected in an extraction that uses countercurrent microflow. We found a theoretical plate number of 4.6 for the extraction of a cobalt complex in an aqueous–toluene countercurrent microflow.Investigations on microscale techniques based on pressure-driven microflows have been advancing rapidly.[1–7] By using the characteristics of a microspace, parallel cocurrent microflow of immiscible phases can be formed by a pressuredriven flow. As flows in a microspace are characterized by a low Re, the cocurrent microflow can be considered as laminar flow. A network based on cocurrent microflow is an effective tool for integrating microchemical processes because sequential contact and separation of immiscible phases can be freely designed in a laminar-flow regime. In this way, we can combine various microunit operations (MUO) under contin-