Utilization of biomass as a chemical resource is a promising strategy for establishing a circular economy. Cellulose, a polymer composed of glucose units, is the most abundant form of biomass, and glucose is a versatile feedstock for chemicals. However, cellulose is a highly recalcitrant material due to its extensive hydrogen-bond (H-bond) network. Kobayashi, Nishimura, and their colleagues discovered that simply dipping cellulose in an aqueous NaOH solution below −28 ℃ makes it more reactive. Thereby, the efficiency of saccharification (the process of breaking down cellulose into sugars) increased 2.2 times.
The NaOH treatment of cellulose, known as mercerization, is a well-established technology to improve the nature of cotton fibers. This process converts the natural crystalline structure of cellulose (cellulose I) to another crystalline form (cellulose II). While it is known that low temperatures increase the transformation efficiency, in this time the researchers found that the condition improves reactivity. This fact indicates that the cold treatment provides another influence on cellulose structure.
Based on these insights, the team analyzed the cellulose sample after the cold base treatment and found that H-bonds that should be included in cellulose II are highly disarranged. The disordered H-bonds no longer effectively protect cellulose from hydrolysis reactions.
This finding will be beneficial for developing improved saccharification technology and for expanding the application of cellulose-based materials.
