One-step extraction of cellulose nanocrystals from high lignin biomass through ammonium persulfate oxidation method

Abstract

Cellulose nanocrystals (CNCs) are one of the emerging nanomaterials that have several interesting and unique properties such as high mechanical strength (Young modulus of 100–140 GPa), low density (1.6 g cm−3), and large surface area (150–250 m2 g−1) that are advantageous in a myriad of applications. In this study, CNCs were successfully prepared from empty fruit bunch (EFB), an agricultural waste from palm oil, using a one-step extraction method using ammonium persulfate oxidation. EFB was directly reacted with ammonium persulfate (APS) at different concentrations (1.0; 1.5 and 2.0 M) at 60 °C for 15 h to undergo the oxidation. The oxidised EFB samples were characterised by dynamic light scattering (DLS), x-ray diffraction (XRD), transmission electron microscope (TEM), Fourier-transform infrared (FTIR), and thermogravimetric analysis (TGA). The FTIR result shows that lignin and hemicellulose in the EFB were successfully removed using one-step extraction method with minimum APS concentration of 1.5 M. The CNCs product has a crystallinity index of 64.1%, a crystallite size of 3.86 nm, and (0 0 2) plane lattice spacing of 3.95 Å. Based on the lattice spacing calculation of all samples, the crystalline structure of cellulose does not change during the oxidation process. The proposed one-step extraction method has been proven to produce the CNCs from EFB with a crystallinity index of 64.1%, a length of 275.9 ± 82.8 nm, and a diameter of 25 ± 5.3 nm.