Life Cycle Assessment of Bio-Based Ethers and Esters: Synthesis from Waste Biomass and Application in Extraction Processes

Bio-based solvents are often claimed to make the processes in which they are used more sustainable from an environmental point of view; such claims usually come from their bio-based origin or their safety profile, which is sometimes better than that of fossil-based solvents. Herein, we intended to deepen the environmental sustainability of the synthesis of two bio-based esters (gamma-valerolactone and ethyl lactate) and two bio-based ethers (2-methyl tetrahydrofuran and cyclopentyl methyl ether) from a life cycle perspective. To this purpose, a Life Cycle Assessment (LCA) was first carried out to compare the environmental impacts of the four bio-based solvent syntheses with those of six fossil-based solvents that they could potentially replace. The assessment was then extended to evaluate the potential benefits of their application in two processes: the extraction of polyethylene from multilayer plastic waste and the extraction of polyhydroxyalkanoates from bacteria. The impacts associated with the synthesis of the four bio-based solvents were substantially higher than those of fossil-based solvents. These higher impacts translate into poorer environmental performance when bio-based solvents were used in the polyethylene extraction processes but not when they were applied to the polyhydroxyalkanoate extraction. These results suggest that the feedstock renewability alone may not be sufficient to improve the sustainability of chemical processes, mainly because of the challenges associated with converting biomass into useful chemicals. Nevertheless, it should be noted that the bio-based routes were largely reconstructed from literature sources and laboratory-scale experiments, while the fossil-based references are based on mature industrial datasets.