Selective Separation of Aromatics by Pervaporation of Azeotropic Toluene/Methanol Mixture Using Polymer Membranes with 2-Pyridyl-Quinoline Groups

Abstract

Copolyamide coPA and its metal–polymer complex coPA–Cu²⁺ (MPC)—new polyheteroarylenes—have been synthesized and used to obtain dense nonporous membranes. Some physical properties of the membranes have been determined: density and glass transition temperature, as well as the water contact angle, which showed increased hydrophobicity in the MPC membrane. Thermogravimetric and differential thermal analyses have been used to assess the thermal stability of the membranes. Transport properties have been studied during pervaporation of a toluene/methanol mixture. The coPA and MPC membranes are predominantly permeable to toluene for all feed mixture compositions. In separation of the azeotropic toluene/methanol = 31 : 69 (w/w) mixture, the coPA membrane showed the best separation factor equal to 64, while the MPC membrane had a higher permeability of 26.7 g/(m² h) than the coPA membrane. Based on the sorption studies of membrane samples in toluene and methanol, the degree of equilibrium sorption has been determined. New membranes will be most cost-effective in separating toluene/methanol mixtures with a low toluene content.