Sonosynthesis of cellulose nanoparticles (CNP) from kenaf fiber: Effects of processing parameters

This study optimizes the isolation parameters of cellulose nanoparticles (CNP) from kenaf fiber using central composite design (CCD). The extraction of CNP was based on three stages (i.e. 3 factors). The independent variables (factors) were NaOH dosage, amount of NaClO2, and sonication time, while the dependent variables (response) were CNP size quality and degradation temperature. Later, size quality responses were fitted with a quadratic polynomial model and degradation point responses with a 2-factor interaction model (2FI). The quadratic model and 2FI models resulted R2 values of 0.95 and 0.79, respectively. In addition, the morphological, thermal analysis, and Fourier transform infrared (FTIR) spectroscopy indicated a progressive removal of non-cellulosic constituents. Furthermore, transmission electron microscopy (TEM) confirmed reduction in fiber diameter from ~170 μm to ~100 nm. The optimal parameters for extraction of CNP were found to be 0.2 g of NaOH/4 g of fiber at first stage, 5 ml of NaClO2/4 g of fiber at the second stage, and 20 min of sonication period during the third stage. Moreover, obtained cellulose nanoparticles were thermally more stable at higher temperature.