Life cycle assessment of cellulose nanowhiskers

Abstract

Cellulose nanowhiskers refer to elongated, single crystalline, rod-like particles that have at least 1 nm-size dimension. Vegetal fibers are an important source of cellulose for the extraction of nanowhiskers that can be used to reinforce the mechanical properties of different polymers. The present study contributes to the environmental performance of cellulose nanowhiskers production processes at their development stage. Thus, particular environmental aspects and related impacts of two cellulose nanowhiskers product systems are evaluated: nanowhiskers extracted from unripe coconut fibers (EUC system) and from white cotton fibers (EC system). The product systems encompassed fiber, electricity, and chemical production processes. All aspects were measured considering the production of 1 g of nanowhiskers. Life cycle inventory analysis was performed while considering the following environmental aspects: energy, water and emissions present in liquid effluents (chemical oxygen demand (COD), biological oxygen demand (BOD), total nitrogen, nitrate, total phosphorus, phenols, furfural, and hydroxymethylfurfural (HMF)). Life cycle impact was also assessed for climate change, water depletion, eutrophication, and human toxicity impact categories. The comparison between the EUC and EC systems showed that nanowhiskers produced in the EC system required less energy and water, emitted less pollutants, and contributed less to climate change, human toxicity, and eutrophication than those produced in the EUC system. Further research to improve the environmental performance of these systems – before scaling up the results from the laboratory to industry – shall focus on improving yield efficiency, reducing energy and water use during the extraction of nanowhiskers, and recovering substances from effluents possessing market value.