Sustainable biochars from carbonization of cellulose filaments and nanocrystals

Cellulose filaments (CFs) and cellulose nanocrystals (CNCs) are sustainable nanomaterials with a wide variety of potential applications. In this paper, the effect of thermal aging on CFs and CNCs, both in acidic (CNC-H) and neutralized (CNC-Na) forms, was studied. Prolonged heat exposure results in useful syngases and causes materials carbonization. Tuning carbonization temperature (between 200 and 400 °C), and pyrolysis atmosphere (air or nitrogen) enables the control of biochar properties. Carbonized nanocrystals form condensed aromatic structures, with CNC-H biochars having notable charcoal potential. Elemental analysis revealed that these biochars have compositions that make them suitable either for soil or gas remediation, anodes, or supercapacitors. Emitted gas analysis shows that gases could be captured and reused as fuels. CFs appear especially promising with one third of their mass converted into alcohols. The insight developed in this work may address the recovery of end-of-life cellulose materials to create value-added products. © 2021 Elsevier Ltd