Size-exclusion chromatography of the soluble lignin products from hydrogen peroxide brightening of mechanical pulps (original) (raw)

1995, Research on Chemical Intermediates

Abstraet-The molar mass distributions and yields of soluble lignin degradation products formed during the alkaline hydrogen peroxide brightening of spruee mechanieal pulp have been determined. These distributions depend on pH, the extent to which the pulp was subjected to solvent extractions, H202 concentration and reaction time. At and below pH 11, there is an excellent eorrelation between the brightness and b' values on pulp and the amounts of residual peroxide and lignin derived produets in solution. Brightening reactions lead primarily to products with intermediate molecular mass values between 1500 and 6000. During multistage brightening, the products formed are initially those with high ionizable phenolic hydroxyl and low carbohydrate contents, and carbonyl-containing moieties. NMR and UV spectroseopic analysis show that products formed include lignin and carbohydrate-containing species. The lignin-originating produets from the later stages contain a lower relative concentration of ionizable phenolic groups and more visible-absorbing and carbohydrate-containing species. Brightness and b* gains during multistage brightening were exponential with product yield.

Sign up for access to the world's latest research.

checkGet notified about relevant papers

checkSave papers to use in your research

checkJoin the discussion with peers

checkTrack your impact