Enhanced butanol production by Clostridium acetobutylicum fermentation using thermo‐responsive poly(N‐isopropylacrylamide)‐grafted PDMS sponge as adsorbent material

Abstract

AbstractBACKGROUNDButanol production through ABE (acetone, butanol, and ethanol) fermentation has attracted a great deal of attention because of its potential to replace petroleum‐based fuels. Low butanol production and productivity due to butanol inhibition are the main challenges to make ABE fermentation viable economically. In this work, polydimethylsiloxane (PDMS) sponge and thermos‐responsive poly(N‐isopropylacrylamide)‐grafted PDMS (PNIPAAm‐PDMS) sponges (with different mass fractions of PNIPAAm on the PDMS surface) were investigated as adsorbents for butanol.RESULTSThe butanol model solutions showed that the adsorption–desorption efficiency of different types of sponges for butanol is highly temperature‐dependent. Higher temperatures exhibited higher adsorption efficiency. In contrast, lower temperatures markedly increased the desorption efficiency for butanol. PNIPAAm‐PDMS with 8.0 wt% of PNIPAAm on the PDMS surface showed as the best adsorbent for butanol. It had adsorption efficiency of 14, 24 and 46% at 25, 37 and 50 °C, respectively. Moreover, 96% of butanol adsorbed was recovered at 25 °C. When it was coupled with a batch ABE fermentation by Clostridium acetobutylicum, butanol production increased by 102% compared to batch fermentation without adsorption. A semi‐continuous fermentation with the initial feeding time at the 60th hour exhibited as the optimum condition. However, it failed to enhance butanol productivity due to a high accumulation of butanol in the broth. Then, a semi‐continuous fermentation with adsorption was conducted, yielding total butanol production of 20 g/L.CONCLUSIONPNIPAAm‐PDMS sponge is proposed as an adsorbent to overcome butanol inhibition in ABE fermentation by temperature manipulation to recover butanol. © 2019 Society of Chemical Industry