LAUSR

Abstract Studies with extractive fermentation using non-ionic surfactant L62 have relieved butanol toxicity and enhanced butanol production. Subsequently, L62 was used for extraction of butanol from a fermentation system using cloud point extraction (CPE). However, the back-extraction of butanol and recovery of surfactant from coacervate phase and reuse of surfactant remains a major challenge. This work presents the CPE of butanol using tri-block copolymer L62 and back-extraction of butanol from coacervate phase in a model system and fermentation broth using Winsor-III microemulsion. Hexane formed Winsor-III microemulsion, which was used for stripping of butanol from coacervate phase and recovery of L62. Butanol partitioned into three phases; 38.24%(w/w) in Om, 0% in BC and 61.4% in Wm. L62 distribution in all three phases was; 0% in Om, 56.57% in BC and 43.35% in Wm. In a model system, 94.6%(w/v) and 99.9% (wt%) of butanol and L62 was back-extracted whereas, in a fermentation broth, it was 99.7%(w/v) and 97.9% (wt%), respectively. Surfactant was successfully reused for 3 runs without affecting its performance i.e. butanol capturing capacity (0.43 g/g of surfactant) which remain unaltered in all the reuse studies. Energy required for butanol separation using surfactant is significantly less than the conventional distillation process.