FUNDAMENTAL STUDY ON PURIFICATION OF ORGANIC COMPOUNDS BY CRYSTALLIZATION WITH APPLYING ELECTRIC FIELD

电场结晶纯化有机化合物的基础研究

• 批准号: 07805070
• 负责人: IWAI Yoshio
• 金额: $ 1.47万
• 依托单位: KYUSHU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07805070/
• 关键词: ELECTRIC FIELD; CRYSTALLIZATION; ORGANIC COMPOUND; PURIFICATION; ZONE MELTING; NORMAL FREEZING; NAPHTHALENE; XYLENOL

Zone melting is one of the most efficient methods to get ultrapure organic compounds. However, it has not yet been applied to separation and purification processes in industrial scale, because the rate of separation is slow. In this work, the effect of an electric field on normal freezing was investigated experimentally, in order to examine whether an electric field can improve the separation efficiency or not. In this work, purification of 3,5-xylenol+naphthalene system was attempted by normal freezing. This is a simple eutectic-forming mixture. The effect of an electric field on the separation efficiency was experimentally examined by applying an electric field in parallel with the solid-liquid interface during solidification at 6,000 V/cm or 10,000 V/cm. The initial impurity concentration was 5wt%. After the solidification, The concentration of the impurity for the solid sample was analyzed by a gas chromatography. Furthermore, the solidification front and the flow pattern in the liquid phase were also observed by using a microscope with a video camera. When 3,5-xylenol was the main component, the concentration of the impurity (naphthalene) was decreased by an electric field. This may due to the convection in the liquid phase induced by the electric field, which was clearly observed through the microscope. On the other hand, when naphthalene was the main component, the concentration of the impurity (3,5-xylenol) was increased by an electric field. It was increased with increasing the strength of electric field. In this case, a lot of small crystals were observed through the microscope when the electric field was applied, so that 3,5-xylenol (impurity) may be adsorbed much more on grain boundaries.

区域熔化是获得超纯有机化合物的最有效方法之一。但是，由于分离速率很慢，因此尚未应用于工业规模的分离和纯化过程。在这项工作中，通过实验研究了电场对正常冷冻的影响，以检查电场是否可以提高分离效率。在这项工作中，通过正常冷冻尝试了3,5-二甲醇+萘系统的纯化。这是一种简单的共晶形成混合物。通过在6,000 v/cm或10,000 v/cm的固体化过程中并行施加电场，通过与固定液体界面并联应用电场，对电场对分离效率的影响进行了实验检查。最初的杂质浓度为5wt％。固化后，通过气相色谱法分析了固体样品的杂质浓度。此外，还通过使用摄像机使用显微镜观察了液相的固化前端和流动模式。当3,5-二甲醇是主要成分时，杂质（萘）的浓度通过电场降低。这可能是由于电场引起的液相的对流，这是通过显微镜明确观察到的。另一方面，当萘是主要成分时，电场增加了杂质（3,5-二甲醇）的浓度。随着电场强度的增加而增加。在这种情况下，当应用电场时，通过显微镜观察了许多小晶体，因此3,5-二甲醇（杂质）可能会在晶界吸附得更多。