Lignins solvents

Presence of humic acids, lignin Solvent extraction ... 

Kraft lignin (Indulin AT), (2) kraft-cooked Bjorkman spruce milled wood lignin, (S) Bjorkman spruce milled wood lignin. Solvent methyIcellosolve-... 

Poor lignin solvent could not be completely recovered. Satisfactory, but gave no advantage. 

Fig. 5.1.4. Ionization difference spectra (AD,-curves) of spruce lignosulfonate and pine kraft lignin Solvents water (lignosulfonate), methyl cellosolve water (8 2, v/v) (kraft lignin)...

Good lignin solvents (e.g., acetone/water, dioxane/water, pyridine, ethylene chloride/ethanol, and acetic acid) exhibit strong IR bands and therefore are not commonly used for solution state IR investigations. An exception is chloroform. 

Suitable solvents are those which dissolve lignin to the maximum extent possible without interfering significantly with the lignin NMR signals. Usually the solvent is deuteriated. The solvent deuterium NMR resonance is usually used for the field-frequency lock signal. The most common lignin solvents and their relevant... 

Table 5.4.4. nC Chemical shifts and signal assignments for spruce and aspen milled wood lignins Solvent DMSO-dh... 

Table 8.2.1. Common lignin solvents of lignins employed in light scattering measurements...

Set the operating temperature the desired cell temperature should be in a range extending up to about 5 °C below the boiling temperature in order to prevent decomposition of the solvent or the sample. Table 8.3.1 lists the temperature generally employed with the usual lignin solvents. 

Hemicellulose [9034-32-6] is the least utilized component of the biomass triad comprising cellulose (qv), lignin (qv), and hemiceUulose. The term was origiaated by Schulze (1) and is used here to distinguish the nonceUulosic polysaccharides of plant cell walls from those that are not part of the wall stmcture. Confusion arises because other hemicellulose definitions based on solvent extraction are often used in the Hterature (2—4). The term polyose is used in Europe to describe these nonceUulosic polysaccharides from wood, whereas hemicellulose is used to describe the alkaline extracts from commercial pulps (4). The quantity of hemicellulose in different sources varies considerably as shown in Table 1. 

In solution, lignin is most conveniendy analyzed quaUtatively and quantitatively by uv spectroscopy. Typical absorptivity values, D, at 280 nm for milled wood (MW) lignins and other types of lignins are Hsted ia Table 4. These values are used for quantitative determination of the lignins ia suitable solvents. 

Solution Properties. Lignin in wood behaves as an insoluble, three-dimensional network. Isolated lignins (milled wood, kraft, or organosolv lignins) exhibit maximum solubiUty in solvents having a Hildebrand s solubiUty parameter, 5, of 20.5 — 22.5(J/cm ) (10 — ll(cal/cm ) > and A// in excess of 0.14 micrometer where A]1 is the infrared shift in the O—D bond when the solvents are mixed with CH OD. Solvents meeting these requirements include dioxane, acetone, methyl ceUosolve, pyridine, and dimethyl sulfoxide. 

The molecular weight of lignin in the wood, ie, of protolignin, is unknown. In addition to difficulties of isolation and purification, the polymer exhibits strong solvent, ionic, and associative effects in solution. An unequivocal method of measurement has not been developed. The polymer properties of lignin and its derivatives have been discussed (10,16). 

Supercritical fluid solvents have been tested for reactive extractions of liquid and gaseous fuels from heavy oils, coal, oil shale, and biomass. In some cases the solvent participates in the reactions, as in the hydrolysis of coal and heavy oils with water. Related applications include conversion of cellulose to glucose in water, dehgnincation of wood with ammonia, and liquefaction of lignin in water. 

Anionic hydrophobic Sulfonated lignin sodium salt, sodium polystyrenesulfonate Buffer or salt solution with organic solvent (e.g., 20% CH,CN in 0.1 M NaNOd... 

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