Innovative Reactive Distillation Process for the Sustainable Purification of Lactic Acid

Abstract

Lactic acid is commonly used in a wide range of fields, such as cosmetics, pharmaceutical products, chemistry, and food. During recent years, its use for new applications, such as the production of biodegradable and biocompatible polymers, green solvents, and oxygenated chemicals, have received considerable attention. However, the relatively high production cost of lactic acid hinders many large-scale applications. It is necessary to develop more efficient methods of separation and purification to cheapen lactic acid production processes. The main objective of this study is to investigate the use of process intensification, particularly the reactive distillation process, for a sustainable purification of lactic acid. To do so, there have been proposed, on the one hand, four intensified alternatives in which synthesis and design are based on thermal couplings and, on the other hand, three alternatives looking for water mass integration. Design and optimization of those modified configurations are carried out employing a stochastic optimization method, using as objective functions some metrics associated with the concept of sustainability (economics, environmental, and inherent safety indexes). A study on the dynamic performance of the configurations through the use of singular value decomposition is carried out in a complementary way. The results in the first redesign stage show improvements in all performance indexes. However, a great difference between the implementation of a thermal coupling that substitutes a condenser instead of a reboiler has been identified. The best scheme, based on a sustainability framework, resulted in a modified process, including a dividing wall column-based scheme.