An environmentally friendly and economical strategy to cyclically produce cellulose nanocrystals with high thermal stability and high yield

Cellulose nanocrystals (CNCs) have been widely used in various industries; however, green, efficient, low-cost and recyclable CNC preparation still presents great challenges. Herein, ferric chloride (FeCl3) solution was used as the solvent to develop a green and recyclable preparation system. Owing to the acidic environment provided by FeCl3, which is a Lewis acid, and the hydrolysis-promoting properties of Fe3+, the amorphous area of the cellulose could be rapidly hydrolyzed under a hydrothermal environment to produce CNCs. More importantly, the used FeCl3 solution could be reused after simple separation. Throughout the entire cycle, the solvent concentration and pH changed only slightly. In the scanning electron microscopy (SEM) results, the prepared CNCs showed a rice-like shape with typical CNC dimensions (diameter of similar to 38 nm and length of similar to 440 nm). The yield was similar to 92%, which was much higher than the yields of previously reported methods of CNC preparation. Furthermore, the produced CNCs also have excellent thermal stability (T-max = similar to 350 degrees C). More importantly, the dispersal performance and large specific surface area of the CNCs were studied by using them as a support for PPy. Owing to the residual Fe3+, Py could polymerize uniformly on the surface of the CNCs. Overall, a green and economical method to achieve sustainable mass production of CNC is provided by this work.

Automated summary

A green and economical method for the sustainable mass production of cellulose nanocrystals (CNCs) was developed using ferric chloride (FeCl3) solution as a solvent. The FeCl3 solution provided an acidic environment for rapid hydrolysis of cellulose to produce CNCs, and could be reused after simple separation. The prepared CNCs showed excellent thermal stability and were able to support the polymerization of Py uniformly on their surface.