Thermopervaporation concept for biobutanol recovery: The effect of process parameters

Abstract

This work addresses the development of energy-saving (low-cost) pervaporation approach for the recovery of biobutanol from the ABE fermentation broth. To achieve this goal, thermopervaporation (TPV) separation of dilute aqueous solutions of 1-butanol through the hydrophobic poly(1-trimethylsilyl-1-propyne) (PTMSP) membranes in the plate-and-frame module with an air gap was investigated. The TPV approach allows separation at atmospheric pressure and in the presence of noncondensing gases of ABE fermentation (carbon dioxide and hydrogen). Different process parameters such as the air gap width, the temperature of the feed mixture, the permeate condensation temperature, and the membrane thickness were studied. The width of the air gap between the membrane and the condensation surface (the cooling plate) should not be lower than 2.5mm. The TPV mode of separation of water/butanol mixture using self-supported PTMSP dense membranes makes it possible to achieve the following process performance: the permeate flux exceeds 0.5kg/(m2h) (membrane thickness is 16μm) and the separation factor for the butanol/water mixture is about 120 (membrane thickness is 115μm) at the atmospheric pressure and at a condensation temperature of 10°С.