The Green Engineering Implications of the Replacement and Recovery of Dipolar Aprotic Solvents in Industrial Manufacturing

A case study has been conducted on the use of solvent substitutes and/or solvent recovery in a resin precursor manufacturing process. The current process uses the dipolar aprotic solvent N-methyl-2-pyrrolidone (NMP) as a synthesis reaction medium. NMP is associated with harmful environmental a health effects. Dimethylsulfoxide (DMSO) and sulfolane are also dipolar aprotic solvents with similar physical properties of NMP but are less harmful. With the substitution of NMP for DMSO or sulfolane in the resin precursor process, total life cycle emissions were reduced by 52% and 61%, respectively. Distillation processes were designed to evaluate the environmental impacts of recovering solvent from the waste. Total life cycle emissions were reduced by 63% when comparing the current operation using NMP with the case of the current operation with solvent recovery. There was no additional significant reduction on life cycle emissions for the cases with solvent recovery for DMSO or sulfolane. Thus, the importance of evaluating all green engineering options through a life cycle assessment is important to fully understand the environmental impact reduction each option possesses.