Nanocelulose: obtenção de celulose em nanoescala utilizando Líquidos Iônicos de Aminoácidos de Colina (LIs[AA][Ch])

Abstract

Nanocellulose (NC) has stood out in the last decade as a promising raw material in several areas in the scientific field, such as biomedicine, the cosmetics industry, the pharmaceutical industry, among others. Methodologies have been developed for the extraction of this biopolymer, arising within this context, the use of Ionic Liquids (LIs) - solvents with the ability to solubilize lignocellulosic biomass, making it prone to produce NC. The main objective of this research was to obtain cellulose nanocrystals or nanofibers from rice husks (Oryza sativa) and pseudostems of banana (Musa cavendishii) - using Choline Amino Acid Ionic Liquids (LIs[AA][Ch]). The methodology consisted of the chemical characterization of the biomasses to identify the contents of moisture, ash, extractives, lignin, hemicellulose and cellulose; synthesis of three LIs: Choline Arginate ([Arg][Ch]), Choline Glycinate ([Gly][Ch]) and Choline Lysinate ([Lys][Ch]), analyzed by Fourier Transform Infrared Spectroscopy (FT- IR) and; Pre-treatment of biomass using synthesized solvents. The samples resulting from the process were analyzed by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD) and Thermogravimetric Analysis (TGA). Cellulose percentages - the main polymer - were 49.64 ± 0.92% and 35.86 ± 0.70% for rice husk and banana pseudostem, respectively. The FT-IR spectra demonstrated efficiency in the synthesis of LIs. SEM micrographs revealed that ([Arg][Ch]) caused greater disruption in the fibers than ([Gly][Ch]) and ([Lys][Ch]). The TEM images allowed the visualization of cellulose nanofibers with a diameter of 2 to 16 nm. The thermogravimetry curves showed that the samples pretreated with ([Arg][Ch]) showed higher thermal stability. Thus, the pre- treatment under study proved to be effective in the destructuring of the amorphous components, and the action of ([Arg][Ch]) on the fibers was able to generate Nanofibrillated Cellulose (CNF).