Abstract:

The enrichment of formic acid in dilute solution was achieved by complex extraction method. An extraction system with high partition coefficient was determined. The continuum model was then applied for describing mass transfer process and predicting the mass transfer characteristics in O/W system. The rate-limiting step was determined to be mass transfer of formic acid in aqueous phase, by comparison of mass transfer rates between extractant in organic phase and solute in aqueous phase. The effect of dispersion size of organic droplets on mass transfer characteristics in O/W systems was determined, indicating inefficient extraction process with low mass transfer coefficients and surficial area in O/W systems. Inert gas was introduced into extraction system and a G/O/W system was developed. The calculation of mass transfer performance in G/O/W system indicates the addition of microbubbles effectively enhances the mass transfer process. Also, suitable volumetric fraction of inert gas was optimized. According to the calculation, a double-membrane-dispersion-device was designed, with which G/O/W double emulsion was prepared and effective enrichment of formic acid from its dilute solution was realized.

Key words: micro-chemical equipment, extraction, emulsions, process intensification, mass transfer

摘要：

以络合萃取法实现了稀溶液中甲酸的富集。确定了高分配系数的萃取体系。根据传质基本方程建立了传质模型，计算并分析了油/水体系中的传质过程，确定传质控制步骤为甲酸自水相至水/油界面的传质。计算了分散尺寸对体系传质性能的影响，结果表明，由于水/油相比高，体系的传质系数低，界面积小，以油/水微分散乳液实现萃取过程，传质效率仍不高。引入惰性气体，并构建气/油/水体系，计算并分析了气/油/水体系中的传质过程并优化了气相加入量，结果表明，气相的加入可以有效促进传质过程。设计了双重膜分散设备，制备了微米尺度的气/油/水双重乳液，并以此实现了稀溶液中甲酸的高效富集。

关键词: 微化工设备, 萃取, 乳液, 过程强化, 传质