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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)/H 2 O 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/H 2 O 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/H 2 O 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).

A procedure was developed for the quantitative assessment of key performance indicators suitable for the sustainability analysis of alternative processes, mainly addressing the early stages of process design. The methodology was based on the calculation of a set of normalized impact indices allowing a direct comparison of the additional burden of each process alternative on a selected reference area. Innovative reference criteria were developed to compare and aggregate the impact indicators on the basis of the site-specific impact burden and sustainability policy. An aggregation procedure also allows the calculation of overall sustainability performance indicators and of an "impact fingerprint" of each process alternative. The final aim of the method is to support the decision making process during process development, providing a straightforward assessment of the expected sustainability performances. The application of the methodology to case studies concerning alternative waste disposal processes allowed a preliminary screening of the expected critical sustainability impacts of each process. The methodology was shown to provide useful results to address sustainability issues in the early stages of process design.