Break | AIChE


As the chemical market continues to expand, the concerns with regards to environmental sustainability have increased due to excessive disposal of chemical solvents. To date, there is no proper mitigation plan to handle such volume of chemical waste. Solvents are used in many industries for purposes such as reaction medium and as extraction, cleaning, and purification agents. These solvents can account for up to 90% of the process by mass and are often discarded after a single use. Incineration, the most widely used process for solvent disposal, is not a “green” method due to the potential detrimental effects to the environment. A systematic framework for solvent recovery has been developed which considers multiple alternative recovery and purification technologies to recover solvents simultaneously through a superstructure-based approach. These technologies are represented as mathematical models that are composed of material and energy balances, utility requirements, equipment design, and costs to assist in determining the most economical method for solvent recovery of any chemical waste stream. Two case studies involving simple binary solvent system and a more complex multi-component system were analyzed and formulated as mixed-integer non-linear programming problems. Selecting solvent recovery options required considerably lower cost in comparison to typical incineration. The solutions obtained from the case studies presented in this work demonstrated the capability of the solvent recovery framework to obtain environmentally friendly and economically viable solvent recovery pathways as an alternative to incineration.