*2.9. Thermogravimetric Analysis (TGA)*

TGA was carried out on a NETZSH STA 449 F3 Jupiter instruments to investigate the general characteristics of lignin thermal decomposition. A sample of approximately 2.5 mg lignin was loaded into alumina pans, where it was gradually heated from 25 to 900 ◦C at a heating rate of 10 ◦C/min under a nitrogen atmosphere with a constant flow of 60 mL/min. When the Klason lignin was subjected a calcination process, the content of the ashes was negligible.
