TITLE:
Thermal, Morphological and Cytotoxicity Characterization of Hardwood Lignins Isolated by In-Situ Sodium Hydroxide-Sodium Bisulfate Method
AUTHORS:
Ahmed Geies, Mohamed Abdelazim, Ahmed Mahmoud Sayed, Sara Ibrahim
KEYWORDS:
Lignocellulose, Lignin, Sweet Sorghum, Rice Straw, Sugarcane Bagasse, FTIR, SEM, TGA, Cytotoxicity
JOURNAL NAME:
Natural Resources,
Vol.11 No.10,
October
13,
2020
ABSTRACT: In the present work, lignin is isolated from three different agro-industrial waste, sweet
sorghum, rice straw and sugarcane bagasse
using in-situ sodium hydroxide-sodium
bisulfate methodology. Characterization was performed using fourier transform infrared analysis (FTIR), scan
electron microscopy (SEM), thermo gravimetric
analysis (TGA). The SEM micrographs showed sponge-like
structure except for sugarcane bagasse lignin reveals rock-like structure. The FTIR indicates the presence of hydroxyl,
carbonyl and methoxyl groups in the
lignin structure. TGA thermograms were relatively same and sugarcane bagasse lignin was found the most thermally
stable up to 201˚C as compared to both of soda and kraft sugarcane bagasse
lignin and its maximal temperature degradation rate DTGmax was found
at 494˚C while 450˚C, 464˚C in addition to thermal stabilities up to 173˚C and
180˚C for sweet sorghum and rice straw lignins respectively. All lignins
exhibited low percentage of bio-char less
than 10% remained unvalotilized at the
end of the thermogravimetric analysis at 800˚C in nitrogen atmosphere, revealing a high conversion yield into volatiles. Moreover, all lignin samples
depicted higher cytotoxic potential towards lung cancer cell line (A549), IC50:
12 - 17 μg/ml. These findings suggest that the in-situ separated lignins would be good candidates for pyrolysis,
polymer composites preparations and seem
to be promising natural anti-cancer agents despite its main utilization as the caner drug delivery substrates.