Title
Characteristics of lignin precipitated with organic acids as a source for valorisation of carbon products
Authors
MPHO NAMANE FRANCISCO JOSE GARCIA-MATEOS BRUCE SITHOLE DERESH RAMJUGERNATH JOSE RODRIGUEZ-MIRASOL and TOMAS CORDERO

Published Volume 50 Issue 3-4 March-April
Keywords lignin, precipitation, black liquor, valorisation, organic acids, thermogravimetric analysis, carbonisation, scanning electron microscopy

Abstract
Lignin is a by-product of multiple lignocellulosic biomass derived industries. Hardwood and softwood lignin were obtained by precipitation from black liquor. The elemental analysis (EA) of the samples indicated that the sulphur content varied between the wood species, SW (softwood) organic acid precipitated samples showing the lowest sulphur content. FTIR showed differences in the intensities of the absorption peaks for each sample. TG analysis of the lignin samples in the presence of air revealed differences in the main degradation region of the TG/DTG curves. The type of organic acid used for precipitation appeared to influence the thermal degradation of the lignin samples. TG analysis under nitrogen resulted in carbon yields that were acceptable for the lignin samples to be considered as raw materials for carbon preparation. SEM images of the samples showed swelling in the lignin chars and revealed differences in the morphology of their structure, showing that different precipitation media would produce different carbon structures.