4.5.1 How Green are ILs?

Complete life cycle assessments of ILs have been attempted to estimate the cumulative energy demand (for synthesis and disposal), the environmental impact and the economic viability (cost of chemicals, energy, disposal, personnel, equipment, and processing). Due to the complexity of the IL life cycle and the limited data available, life cycle assessments have remained a challenge. Previous attempts have instead focused on the optimization of single steps in the IL life cycle, such as the supply of materials and the IL synthesis [138, 139]. It was found that the IL synthesis is expensive [21], and requires large quantities of materials, solvents, energy, and also generates toxic emissions [138]. Therefore, their recy­cling and biodegradability are crucial not only for their economic viability but also to reduce their environmental impact [138].