逆浸透膜による低分子量有機物水溶液の分離特性の研究 その１ ＮＳ‐１００および酢酸セルロース非対称膜

Abstract

Reverse osmotic rejections of some organic acids (acetic acid, propionic acid, butyric acid, valeric acid, succinic acid) and aldehydes (acetaldehyde, propionaldehyde, butyraldehyde) in aqueous solution have been studied using two composite membranes (NS-100 (P3500), NS-100 (P1700)) and cellulose acetate membrane. Separation of solute and permeation through the membrane were measured under the following condition : concentration of solute in most cases is in the range of 50-500 ppm. operating pressure 0.98-2.94 MPa. An analysis of data with Spiegler-Kedem's transport model was carried out to obtain membrane constants such as reflection coefficient σ, solute and hydraulic permeabilities ω and Lp.The result showed that NS-100 membrane gave the superior solute rejection and superior permeation flux. Its rejection was in the range of 40-90%. CA membrane gave the higher salt rejection, but had lower organic solute rejection and permeation flux. In the case of the concentration of solution bellow the 1000 ppm, the rejection does not depend on concentration. But beyond the 1000 ppm, the rejection decreases with the increase of concentration. For organic compounds having the same functional group, the rejection of a solute increases with the increase of molecular weight. Using NS-100 membrane, for organic solute of acids and aldehydes having the same carbon atom numbers, the rejection for acids is lower. This might be attributed to the electrostatic attraction force acting between the solute molecular and skin layer of the NS-100 membrane.