Biobutanol separation from ABE model solutions and fermentation broths using a combined adsorption–gas stripping process

BACKGROUND Butanol is considered a promising sustainable biofuel to partly replace petroleum‐based fuels. However, to become an economically viable biofuel, some challenges need to be overcome in the biobutanol production process such as the low final product concentration caused by product toxicity to the microorganism. Few separation techniques have been proposed to extract biobutanol in situ or ex situ from dilute fermentation broths. In this investigation, the combination of gas stripping and adsorption has been studied experimentally as a process to effectively separate butanol from dilute model solutions and fermentation broths using the advantages of both separation techniques. RESULTS Results showed that the butanol adsorption capacity of activated carbon F‐400 was 261 mg g −1 , for a stripped gas stream from butanol–water binary solution with an initial liquid phase composition of 15 g L −1 butanol, which ended up having a vapour phase composition of 5.8 mg L −1 after gas stripping. This capacity is relatively high compared with the values reported in the literature. Butanol adsorption capacities for a stripped gas stream in equilibrium with ABE model solutions (5.1 mg L −1 ) and fermentation broths (2.3 mg L −1 ) for this adsorbent (211.6 and 219.8 mg g −1 , respectively), were also higher than the capacities reported in the literature. CONCLUSION Combined gas stripping and adsorption could be considered an effective technique for biobutanol separation processes. © 2016 Society of Chemical Industry