Studies On Distribution and Reverse Osmosis Properties of Cellulose Acetate Derivatives for Alcohols.

Abstract

The particles of cyanoethyl cellulose acetate (CACN), hydroxypropyl cellulose acetate (CAHP) and cellulose acetate have been prepared from the solutions containing the same components as reverse osmosis (RO) membrane casting solutions. The pore sizes in particles obtained have been measured by means of gel chromatography. The distribution properties for alcohols have been studied by liquid chromatography. It was found that alcohols were attracted to the surfaces of these membrane materials. The Kd values increased with the increase of carbon numbers of n-alkyl alcohols and followed the order of n->iso->sec->tert-alcohols with different structure. The separation properties of RO membranes casted from these materials for alcohols have also been investigated. It was found that the solute rejection for n-alkyl alcohols reached a maximum when the alcohol molecule containing three carbon atoms and the order of solute rejection of tert->sec--iso-> n-alcohols with different structure existed. The experimental results from liquid chromatography and reverse osmosis have been discussed according to the polar effect (Taft number σ*), nonpolar effect (Small number s*) and steric effect (Steric parameter Es) of the substituent groups in alcohols. Some relations have been found.