Abstract

Cellulose nanocrystals (CNC) have recently received much for their unique mechanical and optical properties, which has led to investigate the best parameters of various processes for CNC production. CNCs are commonly produced by acid hydrolysis of cellulosic fibers. In the literature, an approximation for assessing CNC yield is usually used. Indeed, the method is based in the mass difference of the starting cellulosic material comparing it to the solid residuals (CSR), left by the acid hydrolysis. Hence, assuming that all the missing mass was exclusively transformed in CNC. Chemical oxygen demand (COD) has lately been used for CNC yield assessment using the total Carbon balance of the whole process, ie determining the total carbon of the starting material and the total carbon content of the CNC suspension. This work was aimed to determine CNC yield by COD. The raw material was industrial bleached kraft pulp. Appropriate calibration curves were elaborated using Avicel cellulose. For CNC production, various acid hydrolysis parameters of: temperature, reaction time and acid concentration, were performed and optimized using multivariate experimental design. The best sets of parameters in terms of CNCs were selected. The CNCs yields were between 30% and 50% and evaluated by COD using Avicel calibration curve (R2=0.99). The obtained CNCs were characterized, through Atomic Force Microscopy (AFM). It is concluded that COD measurements are highly reproducible and reliable for the over all Carbon mass balance of the process.