Extraction and characterisation of lignin from residues of Mexican Ocote pine (Pinus montezumae Lamb.) for biofuel production

Abstract

The objective of this research was to extract lignin from residual lignocellulosic biomass of Ocote pine softwood (Pinus montezumae Lamb.) in the south-southwestern region of the Mexican Republic and to determine its potential as raw material to obtain biofuels. The lignin obtained was characterised by Fourier Transform Infrared (FT-IR) spectroscopy, Thermogravimetric Analysis (TGA), Higher Heating Value (HHV) analysis and elemental analysis. The Kraft process was applied for biomass delignification because it is most commonly used in the paper industry worldwide, using sodium hydroxide (NaOH) and sodium sulphide (Na2S) to extract the lignin from the fibres of the forest residues (sawdust and bark) in a 600 mL Parr reactor. The lignin extracted from pine sawdust obtained a better calorific value (28.75 MJ kg−1) than that recovered from the bark (23.61 MJ kg−1). The yield of lignin obtained from 50 g of bark, 5 g, was higher than that obtained from 50 g of sawdust, 2 g. The obtained lignin can be further processed to generate higher value-added products such as liquid biofuels.