Methanol-selective membranes for the pervaporative separation of methanol–toluene mixtures

Pervaporative separation of methanol–toluene mixtures over the entire range of 0–100% is studied at 30°C using cellulose acetate, cellulose diacetate, cellulose triacetate, three blends of cellulose acetate and cellulose acetate butyrate (CBA), co-polymer of acrylonitrile and hydroxy ethyl methacrylate with three different compositions and polyimide membrane. All the membranes studied showed methanol selectivity. Cellulose acetate showed high selectivity with reasonable flux. Cellulose diacetate showed low selectivity and low flux. Cellulose triacetate showed high flux but low selectivity. Of the three blends considered, the blend with 20% (w/w) CAB showed good results with high flux and high selectivity. Co-polymers of acrylonitrile showed the highest methanol selectivity that was comparable to that of the polyimide membrane but with much better flux.