Fractionation of milled pine wood using γ-valerolactone (GVL)/ water solution as a novel organosolv treatment is proposed. Milled pine wood of 0.125 mm was cooked with GVL/water solution of different ratios. The reaction took place at 180 °C for 120 min in a monowave reactor. It was found that the highest delignification in pulp was achieved over the range of 50% to 60% wt. GVL/water. Under the...

Chemical modification of eucalypt lignin was investigated during kraft pulping and chlorine-free bleaching by comparing milled wood lignin, kraft lignin, and pulp enzymatic residual lignins. The syringyl-to-guaiacyl ratio (S/G) from analytical pyrolysis slightly changed during pulping and bleaching (S/G, 3-4) but was higher in the kraft lignin. Semiquantitative heteronuclear single quantum corr...

Laccase-catalyzed oxygen delignification of kraft pulp offers some potential as a replacement for conventional chemical bleaching and has the advantage of requiring much lower pressure and temperature. However, chemical mediators are required for effective delignification by laccase, and their price is currently too high at the dosages required. To date, most studies have employed laccase from ...

Chemical pulps are produced by chemical delignification of lignocelluloses such as wood or annual non-woody plants. After pulping (e.g., kraft pulping), the remaining lignin is removed by bleaching to produce a high quality, bright paper. The goal of bleaching is to remove lignin from the pulp without a negative effect on the cellulose; for this reason, delignification should be performed in a ...

In the past, oxygen delignification studies were mostly performed in batch reactors, whereby the caustic and dissolved oxygen concentrations are changing during the reaction. Also the lignin content and cellulose degradation of the pulp are only established at the end of an experiment when the sample is removed from the reactor. To overcome these deficiencies, a differential reactor system (cal...

Furfural residues produced from the furfural industry were investigated as a substrate for lactic acid production by simultaneous saccharification and fermentation (SSF). Alkaline peroxide was used for delignification of furfural residues to improve the final lactic acid concentration. The residue was treated with 1.3% to 1.7% hydrogen peroxide at 80 °C for 1 h with a substrate concentration of...

A series of kraft pulps were prepared in which the level of calcium was selectively enriched and depleted. These pulps were then oxygen delignified, and the pulps were characterized according to kappa number and viscosity. The residual lignin samples were isolated via acid-hydrolysis and characterized by NMR techniques. The results indicated that the presence of nonprocess elements could impact...

The perspective of the article is to explore kraft cooking at the limits of delignification, i.e. what degree of delignification is needed to obtain fibre liberation and what is the maximum degree of delignification possible in the kraft pulping stage. The reasons for the quite narrow boundaries for sufficient and maximum delignification are explained, and the differences between the behaviour ...

Aalto University, P.O. Box 11000, FI-00076 Aalto www.aalto.fi Author Kaarlo Nieminen Name of the doctoral dissertation Towards a comprehensive model for cooking processes Publisher School of Chemical Technology Unit Forest Products Technology Series Aalto University publication series DOCTORAL DISSERTATIONS 225/2015 Field of research Chemical Pulping Technology Manuscript submitted 23 September...