BACKGROUND Isopropanol, n-butanol and ethanol (IBE) could be used as a clean and renewable biofuel. However, the separation and purification of IBE requires more energy due to the low concentration of IBE in fermentation broth and the existence of azeotropes. Here, we investigate in detail the separation ability of IBE from two typical model solutions by salting-out with potassium pyrophosphate (K4P2O7) as the salting-out agent. RESULTS Increasing the salt content could effectively increase the distribution coefficient and selectivity coefficient of IBE. The recovery of IBE was over 95 wt%, and the dehydration ratio could reach above 99.8 wt%. A higher total organic compound content could increase the recovery of IBE but could decrease the dehydration ratio. The logarithm of solubility of IBE in the aqueous phase or water content in the organic phase has a good linear relationship with the molality of K4P2O7. CONCLUSION This study demonstrated the ability of K4P2O7 to recover IBE from IBE model solutions during the separation process. The results showed that the salting-out method has the potential to save energy in recovering IBE from a real fermentation broth. (c) 2019 Society of Chemical Industry