Thermal stability of extracted lignin from novel millet husk crop residue

Abstract

Recent alarming tones regarding the environment and energy crises have resulted in an emergent need for the utilization of bio-based materials. The current study aims to experimentally investigate the thermal kinetics and pyrolysis behavior of lignin extracted from novel barnyard millet husk (L-BMH) and finger millet husk (L-FMH) crop residue. The characterization techniques FTIR, SEM, XRD, and EDX were employed. TGA was performed to assess the thermal, pyrolysis, and kinetic behavior using Friedman kinetic model. The average lignin yield was obtained as 16.25 % (L-FMH) and 21.31 % (L-BMH). The average activation energy (Ea) was recorded as 179.91–227.67 kJ mol−1 for L-FMH while 158.50–274.46 kJ mol−1 for L-BMH in the conversion range of 0.2–0.8. The higher heating value (HHV) was found to be 19.80 ± 0.09 MJ kg−1 (L-FMH) and 19.65 ± 0.03 MJ kg−1 (L-BMH). The results create a possibility for the valorization of extracted lignin as a potential bio-based flame retardant in polymer composites.