Framework for Solvent Recovery, Reuse and Recycling in Industries

Solvents are commonly used in both fine chemicals and pharmaceutical industries in liquid reactions to aid reaction and purification steps to maintain the quality of the product. In pharmaceutical industries, active pharmaceutical ingredients (APIs) are often formulated in batch organic reactions that utilize solvents as a reaction medium. Solvent amounts and types vary widely depending on the process and physical properties of the system. Solvents can account for as much as 90% of the process by mass, but are often disposed after single use. Due to accidental toxic releases to the environment and occupational safety hazards, legislature has been enacted which support the environmental initiative.

Incineration is the most widely used process for solvent disposal, though it is not necessarily a “green” method. Incineration involves the burning of materials, which releases harmful chemicals such as acidic gases, particulates, and other substances into the atmosphere. Because of potential detrimental effects to the environment, recovery methods are being considered to improve the greenness and overall sustainability of processes in the pharmaceutical and fine chemical industries.

Potential solvent recovery technologies have been researched for the purpose of developing mathematical models in the General Algebraic Modeling System (GAMS) programming language. Some of these technologies include distillation, ultrafiltration, membranes, evaporation and extraction. The models consist of material and energy balances as well as utility requirements, equipment design, and costing to assist in determining the most feasible method for solvent recovery. This work is a part of the US EPA funded project where the goal is to consult with industries and perform typical case-by-case analysis to develop a roadmap for selecting the best pathway for solvent recovery that minimizes cost, reduces the environmental impact, limits waste, and maintains safe operation.