PURIFICATION AND CHARACTERIZATION METHODS FOR LIGNIN BIOMASS AS A POTENTIAL PRECURSOR FOR CARBON MATERIALS

A purification process has been optimized for eucalyptus and sugarcane lignins in order to meet the specification requirements for obtaining high-quality carbon materials free of contaminants. Fluorescence XR was used to determine the inorganic content, comprising Ca, Fe, Al, Si and Na. The ash content after the purification process met the minimum requirements for use as a precursor of carbon materials. Elemental analyses were used to determine the contents of C, N, H, S and O. Fourier transform infrared (FTIR) spectroscopy and the second derivative analysis were used to determine the levels of guaiacyl, syringyl and intramolecular hydrogen interactions. FTIR, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) showed that sugarcane lignin has higher thermal stability and intermolecular interactions than kraft lignin. Carbon-13 nuclear magnetic resonance ( 13 C NMR) spectroscopy was used for the quantitative determination of structural chemical groups and contaminants. The results indicated a large potential for the application of the obtained lignins as precursors for carbon materials.