Cellulose hydrolysis in liquid medium - such as acid or enzyme solutions - has been the most common setup for cellulose degradation. However, liquid state treatment rarely allows for the visualization of the degradation process itself because the overall morphology of the substrate is altered in several hierarchical levels, thereby interfering with observations at specific length scales. Hydrolysis with gaseous acid, by contrast, usually does not induce any drastic morphological changes on the cellulose substrate. To this end, we were able to visualize the acid hydrolysis with HCl gas on individualized cellulose nanofibers (CNFs) deposited on a flat substrate. Cleavages caused by the acid hydrolysis along the CNFs were clearly observed by atomic force microscopy (AFM) and possible chemical changes were monitored by x-ray photoelectron spectroscopy (XPS). By applying a different set of gas pressures and extending the hydrolysis time, progressive degradation and possible formation of nanocrystal segments in the solid state was revealed. Our study targets in deeper understanding of principles and phenomena occuring throughout the hydrolysis of cellulose.

Visualizing acid hydrolysis of cellulose nanofibers by hydrogen chloride gas

2019 Spring National Meeting

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