Strategies Leading to Novel Nanomaterials and Performance Industrial Products, 2011

 

Project Leader

You-Lo Hsieh, professor, Division of Textiles and Clothing, UC Davis

 

In its second year, this project is successfully developing efficient processes to isolate rice straw components and convert them to advanced nanomaterials and performance industrial products.

Electron microscopy of isloated rice straw cellulose (top), self-assembled cellulose nanocrystals (middle), and mechanically defibrillated nanofibers (bottom).

In 2010, scientists streamlined two fractionation routes to isolate four major rice straw components—cellulose, hemicellulose, lignin, and silicon­­­—and derived cellulose nanocrystals from one of those routes. Goals for 2011 were to improve the yield of cellulose nanofibers and to develop functional carbon fibers and silica nanomaterials.

Two distinctively advantageous processes have been successfully demonstrated. Cellulose can be isolated in a number of ways. The optimal method derives pure cellulose in a three-step process involving extraction, acidified sodium chlorite, and potassium hydroxide to remove wax, lignin, and hemicellulose.  In another process using sodium hydroxide and hydrogen peroxide, hemicellulose, lignin, and silicon can be effectively collected—individually and in mixtures.

Cellulose nanocrystals (CNC) with diameters less than 10 nm and lengths ranging from 200 nm to 400 nm have been generated. These CNCs exhibit a self-assembling behavior that has not been seen in other sources of biomass. The self-assembled fibers were highly stable under vigorous stirring or shaking experiments and maintained fiber shape, thus showing great promise for processing into advanced materials.

Several isolation procedures have been optimized to allow versatile and efficient pathways for generation of the four major rice-straw components at high yields. Silica nanodisks and carbon fibers were synthesized from rice straw silicon and hemicellulose/lignin, respectively.

Successful conversion of rice-straw components to cellulose nanocrystals, self-assembled fibrils, as well as silica gel and nanoparticles, validates the proposed concepts and sets the foundation for further development into nanomaterials for value-added industrial products.