Physico-Chemical Characterization of a Fractionated Kraft Lignin

Abstract

A kraft lignin was leached from a softwood pulp and fractionated by ultrafiltration. The fractions were characterized in respect to phenolic group content, molecular weight distributions and self-diffusion coefficients. The 1 H-Pulsed Field Gradient (PFG) NMR self-diffusion measurements and the High-Pressure Size Exclusion Chromatography (HPSEC) analysis of the fractions, were seen to correlate fairly well.From the self-diffusion measurements, the mass-weighted median hydrodynamic radii of the diffusants in the fractions, were calculated assuming spherical fragments.Furthermore, the content of phenolic groups in the fractions, was found to decrease by increasing hydrodynamic radius and molecular weight, but the calculated median surface charge densities of the macromolecules, were determined to be constant in the range of oligomers up to at least 65 structural units.

Production of carboxymethylated lignin and its application as a dispersant

“…The main novelty of this work was the production of a dispersant from hardwood kraft lignin via carboxymethylation for clay suspensions. The impact of carboxymethylation on the charge density of the product, which is known to be an important parameter for dispersants (and basically polyelectrolyte systems) [19], is discussed for the first time. In this context, the influence of reaction parameters on the preparation of carboxymethylated lignin from hardwood kraft lignin using sodium chloroacetate under alkali conditions were studied in order to obtain carboxymethylated kraft lignin with a high charge density and solubility.…”

Morphological variation of lignin biomacromolecules during acid-pretreatment and biorefinery-based fractionation

“…Normally, the morphological property of lignin biomacromolecule is determined in various solutions by means of viscometry, size exclusion chromatography, ultracentrifugation, pulsed field gradient spin-echo NMR (PGSE-NMR), etc. (Garver and Callaghan, 1991;Sarkanen et al, 1982;Norgren and Lindstrom, 2000). Information on the morphology of dry lignin could facilitate the understanding of interfacial properties of lignin (Vainio et al, 2004).…”

Characteristics and Properties of Soda Lignin Obtained from Aspen Wood By-Products

“…It can be seen that the distribution of the lignin particles in alkaline medium has a monomodal nature with average hydrodynamic radii of 78 nm. Literature data show that the species with hydrodynamic radii of 3.0 nm are close in sizes to the individual macromolecules of lignin [6,7]. Hence, the observed particles are the associates, consisting of individual macromolecules of aspen lignin.…”

“…2) exhibit a pronounced maximum at 278 and 282 nm at pH 3.5 and pH 12.7, respectively. In strong alkaline media, they represented the integrity of absorption bands in the form of strongly or weakly pronounced shoulders, reflecting the presence of different substitutes in the aromatic rings of the lignin macromolecules, which effect on the intensity and the location of absorbance bands [6]. The pronounced shoulders at 240, 278 and 348 nm on the aspen lignin ionization curve in strong alkaline medium may indicate the presence of aromatic structures, containing non-etherified hydroxyl groups, conjugated carbonyl groups and aromatic carboxyl groups in lignin macromolecules.…”