Synthesis and Characterization of Nanocellulose from Lignocellulosic Agricultural Biomass by Acid Hydrolysis

The present study emphasizes lignocellulosic materials like agricultural biomass such as ragi stalk also known as Finger Millet Stalk (Eleusine coracana), mango wood (Mangifera caesia) and groundnut husk (Arachis hypogaea) were transformed into cellulose by pretreatment with 5% NaOH and 5% NaClO2 solution. In addition, the cellulose obtained was transformed into nanocellulose (NC) using acid hydrolysis, ultrasonication and centrifugation. The X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and thermogravimetry and differential thermal analysis (TGA/DTA) were used to characterize the synthesized nanocellulose. According to the FTIR findings, the chemical structure of cellulose synthesized from these agricultural biomasses was not affected by the synthetic approach, however, the synthetic procedure employed affects the morphology/surface topology of synthesized nanocellulose as confirmed by SEM. XRD studies reveal the crystalline and semi-crystalline nature of the synthesized nanocellulose. TEM monographs illustrate the surface structure and size of the synthesized nanocellulose ranging from 8 to 17 nm. The thermal stability of nanocellulose is revealed by TGA/DTA studies and the obtained nanocellulose shows thermal stability in the range of 240 to 327 ºC.