Obtaining cellulose nanocrystals from pineapple crown fibers by free-chlorite hydrolysis with sulfuric acid: physical, chemical and structural characterization

Brazil is the second-largest world producer of pineapple and generates almost 45% of its initial mass in wastes after industrialization, mainly due to the inappropriate deposition of peel and crown, which contribute to environmental damage. In this study, pineapple crown fibers (PCF) residues were investigated as an essential alternative to produce cellulose nanocrystals (CNC). It was used a free-chlorite hydrolysis reaction combined with sulfuric acid using different times and acid concentrations to obtain CNC after obtaining of the bleached cellulose. CNC`s were characterized by zeta potential, TGA, XRD, FTIR, and TEM. The main results showed that the chemical treatments were efficient in the removal of amorphous components, increasing the fiber whiteness and the crystallinity index. The best result obtained was for a concentration of 64% of H2SO4 for two hours with values of particle size of c.a. 140 nm and Zeta potential of - 47.96 mV, validating the use of the PCF for CNC.