Investigation of the Structural, Thermal and Morphological Properties of Nanocellulose Synthesised from Pineapple Leaves and Sugarcane Bagasse

Background: Nanocrystalline celluloses (NCCs), also known as nanocelluloses derived from natural renewable resources, have elicited much interest from researchers. The annual local agricultural residues of pineapple leaves and sugarcane bagasse are abundant and must be used properly. The detailed comparative analysis of chemical, physical and thermal properties conducted in this work demonstrates that several types of agro-waste can be utilised economically and reasonably for various applications. Methods: NCCs were successfully isolated by the pre-treatment (alkaline and bleaching) and acid hydrolysis of pineapple leaves and sugarcane bagasse. The structural, crystallinity, morphological and thermal properties were evaluated via Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). Results: The FTIR spectra revealed an extensive removal of hemicellulose and lignin from the extracted NCC. Morphological investigations conducted through TEM revealed that the NCC nanostructure had a needle-like shape, whereas SEM showed an irregular rod-like shape. The XRD pattern proved the crystallinity of the isolated NCC from both samples. The crystallinity indices of NCC from pineapple leaves and sugarcane bagasse were 76.38% and 74.60%, respectively. NCC's thermal stability increased in both samples at different purification stages. Conclusion: Pineapple leaves and sugarcane bagasse can be the industry's primary source of raw materials and a possible alternative for costly and non-renewable materials. The use of NCCs from these agro-waste forms is beneficial and can provide considerable biomass to the agricultural industry with nano-energy-based markets.