Developmental Study on a Liquid - Liquid Extractor with Supported Interface in a Porous Material

液-液萃取装置是一种新型的传质装置，在多孔材料中保持液-液界面，使每种液体都能容易地通过，本研究采用金属丝网制成的多孔管，进行了以下两种实验来考察这种装置的特性。一个是水-煤油体系的流体流动实验，考察多孔管中支撑液-液界面的稳定性;另一个是以醋酸为溶质的萃取实验.流体流动实验研究了几种不同目数的金属丝网管保持稳定界面的工作范围。在实验中，水在该管道中向下流动，煤油在外部环形空间中向上流动。其工作范围受各相静压差的影响，并随丝网目数的增加而变宽。日 ...更多信息 结果表明，界面张力引起毛细管压力起着重要作用。但定量的解释尚不能成功.萃取实验在水-煤油体系中加入醋酸后，界面张力急剧下降，操作范围变窄。因此，提取实验仅使用网眼数为400的金属丝网管进行，该金属丝网管是上述所用管中最细的一种。实验结果用总传质系数Kw与界面面积A的乘积进行评价。假设界面位于多孔管的外表面（亲水性）和内表面（疏水性），可以预测KwA值介于估计值之间。由K_wA的估算值可知，多孔壁内的传质阻力是控制性的，受水相和煤油相流速的影响较小。但KwA的实验结果与估算值相差甚远，且随水流量的增加而略有增加。根据这些结果，我们认为水相或煤油相的整体流动可能会影响多孔壁内的流体运动，从而促进传质速率。因此，我们计划澄清所使用的多孔材料，其孔径和壁厚对传质速率的影响。少

A liquid-liquid extraction equipment proposed here is a new type of mass transfer equipment keeping a liquid-liquid interface in a porous material through which each of the liquid can pass easily.In this reseach, using porous pipes made of wire netting the following two kinds of experiment were performed to examine the characteristics of this type of equipment. One is a fluid flow experiment for water-kerosene system to investigate on stability of the liquid-liquid interface supported in the porous pipe and the other is an extraction experiment using acetic acid as a solute.1. Fluid flow experiment The operating range keeping a stable interface was investigated for a few pipes made of wire netting of different mesh number. In the experiment, water flows downward in this pipe and kerosene flows upward in the outside annulus. The operating range was subjected to the difference between the static pressures of each phase and became wider with increase of mesh number of the wire netting. Th … More is result duggests that capillary pressure due to interfacial tension plays an important role. But the quantitative explanation can not yet been succeeded.2. Extraction experiment By adding acetic acid to water-kerosene system the interfacial tension decreased sharply and the operating range was found to become narrow. So the extraction experiment was conducted using only a wire netting pipe of mesh number-400, the finest one among the pipes used above. The experimental results were evaluated by the product of the overall mass transfer coefficient K_w and the interfacial area A. The K_wA value could be predicted to be between the estimated ones under assumption that the interface is at the outer face (hydrophilic) and the inner face (hydrophobic) of the porous pipe. From the estimated vakue of K_wA it was found that the mass transfer resistance in the porous wall is controlling and is less affected by the flow rate of water- and kerosene-phases. However, the experimental results of K_wA showed a few times the estimated ones, and increased slightly with increase of the water flow rate. On these results we consider that the bulk flow of water- or kerosene -phase may influence fluid movement within the porous wall and this promotes the mass transfer rate. Therefore we are planning to clarify the influence of the porous material used, its pore size and the wall thickness on the mass transfer rate. Less