Adsorptive separation and recovery of biobutanol from ABE model solutions

Abstract

Adsorption is one of the most energy efficient techniques for butanol separation from dilute fermentation broths. To develop an efficient butanol adsorption process, adsorption and desorption are equally important since it is paramount to be able to desorb the adsorbed butanol to produce a high concentration butanol product. Although there are a good number of investigations done to find suitable adsorbents for this process, only few studies considered the desorption process. In this study, activated carbon F-400 was used as the butanol adsorbent since it has a high adsorption rate and capacity and is selective to butanol in the presence of other fermentation broth components. The thermal desorption process was performed in adsorption–desorption cycles both for butanol–water and acetone–butanol–ethanol (ABE) model solutions. The results for 1.5 wt% feed butanol–water binary solutions showed that the butanol adsorption capacity and the recovery of butanol were fairly constant (around 302 mg/g and 84 %, respectively) in subsequent adsorption–desorption cycles confirming that all the amount of adsorbed butanol is desorbed and the adsorption column could preserve its initial adsorption capacity in different cycles. Similar performance was obtained for butanol separation from the ABE model solution containing 1.2, 0.5, 0.2, 0.5, 0.5, 0.4 and 0.4 wt% butanol, acetone, ethanol, butyric acid, acetic acid, glucose and xylose, respectively. The adsorption capacity and recovery for butanol were 170 mg/g and 80 %, respectively.