Azeotropic Distillation for the Recovery of IPA

Waunakee, WI

A leading global supplier of high quality active pharmaceutical ingredients came to Koch Modular for a complete modular distillation system that recovers isopropanol (IPA) from aqueous process streams.

Though IPA is used in the manufacture of several pharmaceutical products, including medicinal tablets, waste solvent disposal costs make up one of the primary concerns in the pharmaceutical industry.

Furthermore, because IPA forms an azeotropic mixture with water, solvent recovery of IPA by conventional distillation is not possible. Instead, azeotropic distillation can be used, tackling waste solvent disposal cost concerns and offering cost-saving and environmental benefits.


Each project presents a unique set of challenges that Koch Modular engineers are well-equipped to take on. For example, the separation of an IPA/water azeotropic mixture is difficult and cannot be achieved by conventional distillation methods. Also, this IPA recovery system requires operating flexibility, first operating as a batch process to approach the desired azeotropic composition, followed by a continuous process to introduce the appropriate entrainer into the mixture. There were additional specifications, such that the system is multipurpose, can perform different separations, and has automated start-up and shutdown. Acknowledging that the client harvests pharmaceutical components from pig intestines, Koch Modular engineers also paid special attention to proper solids handling to avoid any fouling and accounted for inconsistencies inherently present in natural materials.


Koch Modular provided two modules as part of a system designed to perform an azeotropic distillation on an IPA/water azeotropic mixture. The system first operates in a batch mode to recover IPA, near it’s azeotropic concentration.

The system is then operated in a continuous mode to dry the IPA using azeotropic distillation with IPE as the entrainer, producing a product stream of 96 wt% IPA, 4 wt% water and trace DIPE. An IPE/water heterogeneous azeotrope is also formed and subsequently separated by decanting.


The recovery and reuse of IPA provide an opportunity to reduce waste solvent disposal costs and meet increasing environmental and commercial pressures imposed on the pharmaceutical industry.

The system provided successfully operates in both batch and continuous processes, achieving the difficult separation of an azeotrope, appropriately handling pig pancreas solids, and mitigating any fouling during the solvent recovery.