A background review on falling film distillation in wetted -wall columns: From fundamentals towards intensified technologies

In response to the worldwide need for more sustainable chemical processes, distillation became target of major efforts for efficiency improvement. Leveraged by process intensification, several technologies have been pro- posed to reach a more compact, safer, and less energy -intensive equipment. Falling film columns were in- tensively used for heat and mass transfer research in last century. Noteworthy, studies proposing the falling film technology in distillation condition highlighted numerous advantages, such as low residence time and simple constructive structure when compared to conventional distillation, as well as high transfer rates due to the small thickness that flows in longitudinal direction of the distillation wall. Therefore, this review brings a historical perspective of theoretical and experimental works as well as deposited patents on falling film distillation from the beginning of 20th Century to present. Theoretical background and conceptual aspects related to efficiency improvement and process intensification were deeply discussed, aiming to guideline future perspectives in chemical separations.