Comparative cradle-to-gate life cycle assessments of cellulose dissolution with 1-butyl-3-methylimidazolium chloride and N-methyl-morpholine-N-oxide

Abstract

In this paper the expected environmental impacts of the industrial cellulose dissolution with the ionic liquid 1-butyl-3-methylimidazolium chloride (Bmim Cl) were analyzed through a “cradle to gate” Life Cycle Assessment (LCA). In order to weigh up the “greenness” of the process, the analysis was performed through a comparison with the well established environmental friendly N-methyl-morpholine-N-oxide (NMMO)/H₂O process. Although dissolution of cellulose in Bmim Cl has not been used for industrial production of cellulose fibers to date, results from LCA suggest that it could be interesting from an environmental point of view since its impacts are similar to those of the NMMO/H₂O process. Specifically, the process with Bmim Cl generates a higher environmental load on abiotic resource depletion, emissions of volatile organic compounds and ecotoxicity than the NMMO/H₂O process. Conversely it has some environmental advantages with regards to human toxicity. In both cellulose dissolution processes, the major contributions to the environmental impacts come from precursor syntheses. In addition to the comparative analysis of the two cellulose dissolution processes, the paper reports the complete life cycle inventory (LCI) of the two solvents, Bmim Cl and NMMO, and their life cycle impact assessment (LCIA).