Life cycle assessment of emerging environmental technologies in the early stage of development: A case study on nanostructured materials

The use of nanostructured materials has been recently proposed in the field of environmental nanoremediation. This approach consists in using nanomaterials not directly, but as building blocks for the design of nano-porous micro-dimensional systems, overcoming the eco- and health-toxicology risks generally associated with the use of nano-sized technologies. Herein we report the use of life cycle assessment (LCA) as an eco-design tool for optimizing the production of cellulose nanosponges (CNS), nanostructured materials recently developed for water remediation purposes. LCA was applied from the acquisition of raw materials to the synthesis of CNS (from cradle-to-gate), considering three production systems, from the lab-level to a modeled scale-up system. The lab-scale LCA identified the main environmental hotspots, namely the energy-consuming steps and the final purification of the material (washing step). In a second lab-scale production, an improvement action could be implemented, switching the washing solvent from methanol to water and decreasing the washing temperature. A second LCA showed a reduced contribution to the impacts from the materials, while the global impacts remained within the same order of magnitude. A simulated scale-up of the process allowed to optimize the energy-consuming steps and the water consumption, through internal recycling. A third LCA assessed the resulting benefits and a decrease in the global impacts by two orders of magnitude. Our study contributes to the discussion of LCA community, providing a focus on the importance of scaling-up of emerging technologies, namely nanostructured porous materials, highlighting the benefits of a LCA based approach since the very beginning of product design (eco-design).