Abstract

Lignin was isolated from banana pseudo stem, palm frond and coconut husk. The moisture content of the banana pseudo stem and palm frond was determined gravimetrically. The lignin was isolated by alkaline hydrolysis with NaOH followed by precipitation with 72% H₂SO₄. The isolated lignin was then copolymerized with methyl methacrylate via free radical mechanism. The lignin and the corresponding copolymers were characterised by FTIR analysis.

The lignin content in banana pseudo stem, palm frond and coconut husk were respectively 16%, 14% and 13% while the grafting percentage of the corresponding lignin with methlymethacrylate (MMA) are 24%, 21% and 19%. These implied that production of lignin from agricultural wastes could reduce the latter solid wastes.

The FTIR analysis of the different lignin showed important peaks such as O-H band between 3433 cm^-1 and 3450 cm^-1; C=C band around 1515 cm^-1 was absent in palm frond lignin; and C=O band was only observed in coconut husk lignin at 1696 cm^-1.  There was a significant difference in the absorption band of the C-O (ether) of the lignin between 1107 cm^-1and 1198 cm^-1. The shift in the absorption peaks in the spectra of the isolated lignin for the different sources of the lignin and the grafting percentage corroborate the fact that the properties and composition of lignin depend on the source of the lignin. The FTIR analysis of the copolymers also showed two prominent peaks for C=O band between 1680 cm^-1 and 1708 cm^-1; and C-O (ester) between 1220 cm^-1 and 1320 cm^-1 that were absent in the lignin.  These confirm the presence of the acrylate functional groups.

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