METHOD AND FOR SEPARATION AND COLLECTION OF PURIFIED ALKALI METAL SALT

摘要

The present invention relates to a method for separating and collecting a purified alkali metal salt from an aqueous alkali metal salt solution, which is characterized by involving a treatment step of removing any purification-disturbing substance by a separation membrane which fulfills both the glucose removal ratio and the isopropyl alcohol removal ratio respectively represented by formulae (I) and (II) when an aqueous glucose solution having a temperature of 25°C, a pH value of 6.5 and a concentration of 1000 ppm and an aqueous isopropyl alcohol solution having a temperature of 25°C, a pH value of 6.5 and a concentration of 1000 ppm are separately passed through the separation membrane at an operation pressure of 0.75 MPa: (I) glucose removal ratio = 90%; (II) (glucose removal ratio) - (isopropyl alcohol removal ratio) = 30%.