Comparative Evaluation of the Efficient Conversion of Corn Husk Filament and Corn Husk Powder to Valuable Materials via a Sustainable and Clean Biorefinery Process

Corn husk is usually burned and discarded, resulting in environment pollution and a waste of resources. To make better use of corn husk, in this work, corn husk filament (CHF) and corn husk powder (CHP) were first separated and then the comparative evaluation of efficient conversion of CHF and CHP to valuable materials was carried out via a sustainable route [i.e., one-step formic acid (FA) hydrolysis]. After FA fractionation, over 90% hemicellulose could be removed (mainly converted to xylose), about 80% lignin with high purity could be isolated, and the fractionated cellulose solid residue was used to fabricate cellulose nanofibrils (CNFs) and functional cellulose nanopaper (CNP). Results showed that, compared to CHP, the CHF with lower density, longer fibers, and higher crystallinity could be easier to hydrolyze, and the resulting CNFs had a smaller diameter and higher crystallinity, leading the final CNP to have better mechanical properties. The maximum tensile strength and toughness of the resultant CNP reached up to 177.0 +/- 6.1 MPa and 13.3 +/- 1.7 MJ.m(-3), respectively. Also, the CNP with high crystallinity and great thermal stability exhibited excellent water resistance and good barrier properties. Thus, the present work provides a sustainable and new route to make full use of corn husk through the production of xylose, high-purity lignin, and functional CNP.