From azeotropes to dehydrated alcohols: dual‐stage salt separation of isobutanol and ethanol for green biorefining

Abstract BACKGROUND The efficient separation of isobutanol–ethanol–water azeotropes remains a critical bottleneck in the advancement of sustainable isobutanol production, where conventional distillation is both energy‐intensive and inefficient. Here, we report a low‐energy, salt‐assisted separation strategy employing alkaline potassium salts, with K 2 CO 3 demonstrating exceptional dewatering capability. RESULTS Under near‐saturation conditions, a single‐step salting‐out process enables the recovery of over 99.8 wt% of isobutanol and ethanol from aqueous mixtures. However, due to the inherent limitations of the salting‐out equilibrium, a one‐step process cannot fully eliminate residual water. To address this, we introduce a sequential two‐step salting‐out strategy, which reduces the water content in the organic‐rich phase to 3.44 wt%, effectively surpassing the dehydration performance of conventional methods. CONCLUSION Through this method, a traditional distillation can be replaced by a scalable, energy‐efficient, and industrially feasible purification method, which can lead to a paradigm change in the recovery of alcohols from azeotropic mixtures. © 2025 Society of Chemical Industry (SCI).