Abstract:

The finite element analysis of the two-phase laminar flow in the microchannel with cross-shaped and cylindrical auxiliary structures was carried out by Comsol software. Meanwhile, liquid-liquid extraction experiments were carried out with three cases including the smooth microchannel. Copper sulfate was used as the aqueous phase, and DZ988N extractent diluted to 30% by 260^# solvent oil was used as the organic phase. The cylindrical auxiliary structure promotes the diffusion of Cu²⁺ in the aqueous phase, and the extraction efficiency was the highest, which can reach more than 90%. The cross-type auxiliary structure sometimes promotes and inhibits of Cu²⁺ diffusion in the aqueous phase, and the extraction efficiency was unstable, with the highest being 89.8% and the lowest being 74.6% when the given flow rate was in the range of (0.5×10^-3) ~(5×10^-3) m/s. If chemical reaction was not considered and the two phases in the microchannel were laminar in the experiments, the diffusion of Cu²⁺ depended only on the concentration gradient , and the diffusion efficiency could characterize the extraction efficiency. The diffusion efficiency obtained by the finite element method agreed well with the experimentally obtained extraction efficiency values, and the flow characteristics such as the two-phase flow field distribution was further obtained, and the difference of diffusion efficiency under different auxiliary structures was explained.

Key words: micro-fluidic chip, multiphase laminar flow, liquid-liquid extraction, auxiliary structure

摘要：

运用Comsol软件对带有十字形和圆柱形辅助结构的微通道内两相层流进行了有限元分析。同时，以硫酸铜溶液为水相，被260^#溶剂油稀释30%的DZ988N萃取剂为有机相，并以光滑微通道为参照，开展了相关的液-液萃取实验。当给定流速在(0.5×10^-3) ~(5×10^-3) m/s范围内，圆柱形辅助结构能够促进水相中Cu²⁺的扩散，萃取效率最高，均能达到90%以上；而十字形辅助结构时而促进时而抑制水相中Cu²⁺的扩散，萃取效率不稳定，最高89.8%，最低74.6%。实验中，微通道内的两相为层流，如不考虑化学反应，Cu²⁺的扩散则仅依靠其浓度梯度差，扩散效率可表征萃取效率。有限元计算得到的扩散效率与实验获取的萃取效率值吻合良好，进一步得出了两相流场分布等流动特征，以解释不同辅助结构下的扩散效率差异。

关键词: 微流控芯片, 多相层流, 液-液萃取, 辅助结构