Separation and Concentration of Isobutanol from Dilute Aqueous Solutions by Pervaporation Process

Isobutanol produced from the fermentation process has a low concentration and needs to be concentrated and purified for use in different applications. There are many separation processes for isobutanol recovery from the fermentation broth. A hydrophobic pervaporation process was employed to separate isobutanol from its dilute aqueous solutions. For this purpose, composite poly dimethyl siloxane (PDMS) membranes with various active layer thicknesses were used for the recovery of isobutanol and the effect of some operating parameters such as membrane thickness, feed concentration and feed temperature on the separation performance of pervaporation was investigated. The results indicated that the permeation flux and isobutanol selectivity increased by an enhancement in the feed concentration. For example, by increasing the isobutanol feed concentration from 2 to 5%wt., the total flux and membrane selectivity enhanced by more than 50%. When the membrane thickness varied from 2.3 to 12.9 μm, the permeation flux was reduced by about half, but the selectivity increased more than 2 times. Also, higher temperature led to higher permeation flux, while the selectivity decreased with an enhancement in the feed temperature.