Isolation of residual lignin from softwood kraft pulp. Advantages of the acetic acid acidolysis method.
Lignin in kraft pulp was extracted by enzymatic hydrolysis of the carbohydrates, acidolysis with dioxane-water-HCl (conventional method), and acidolysis with acetic acid-water-ZnCl2. The latter method was shown to extract lignin with a better yield than for conventional acidolysis and with a much lower content in impurities than for enzymatic hydrolysis. It was confirmed by 13C NMR analysis of the lignin samples that conventional hydrolysis modified the lignin polymer, causing the cleavage of some aryl-ether linkages. The cleavage was also observed on a model compound submitted to the same extraction conditions. In that respect, the acetic acid-water-ZnCl2 method was less damaging and consequently more suitable for analytical purposes.
Lachenal
Dominique
D
Laboratoire de génie des procédés papetiers, GP2-UMR 5518, Ecole française de papeterie et des industries graphiques, domaine universitaire, BP 65, 38402 Saint-Martin-d'Hères cedex, France. Dominique.Lachenal@inpg.efpg.fr
Mortha
Gérard
G
Sevillano
Rose-Marie
RM
Zaroubine
Michail
M
D019342:Acetic Acid / Q000494:pharmacology*; D007221:Industry / Q000379:methods; D008031:Lignin / Q000032:analysis* / Q000737:chemistry* / Q000302:isolation & purification*; D014934:Wood
C076151:Kraft lignin; D008031:Lignin; D019342:Acetic Acid