Design of a Continuous Solvent Recovery System for End-to-End Integrated Continuous Manufacturing of Pharmaceuticals

Disadvantages of the traditional batch process have encouraged the pharmaceutical industry to explore continuous manufacturing, including end-to-end approaches, such as integrated continuous manufacturing (ICM). As the pharmaceutical industry is relatively solvent-intensive, solvent recovery is necessary to achieve the goal of sustainable manufacturing. A simple vapor–liquid equilibrium (VLE) setup was designed, and its reliability was assessed, from which the VLE data for a two-solvent system were obtained and, accordingly, the distillation columns were designed. The recovered solvent purities were >99.9 wt % for the first solvent (Solvent 1) and >99.8 wt % for the second solvent (Solvent 2), and the recovery yields were 94.9% and 98.3%, respectively. From the E-factor analysis, approximately 30% less waste was generated in the ICM process compared with a corresponding batch process. After integration of the solvent recovery system, the E-factors for both the batch and ICM processes decreased significantly, from 1.63 to 0.29 and from 0.77 to 0.21, respectively.