the kinetics of old corrugated container (occ) soda-oxygen delignification was investigated. three delignification temperatures (145,165 and 175ºc) were applied. the pulping duration was adjusted at 150 minutes and the measurements were conducted at 10 minutes intervals. the pulping consistency, oxygen pressure and active alkali were constant at 10%, 6 bar and 18% naoh respectively in all pulpi...

In an effort to augment the efficiency of an oxygen delignification stage, we examined the effectiveness of various heterocyclic aromatic nitrogen compounds as possible activators of such a stage. It was shown that a variety of such compounds may act as activators in the presence of hydrogen peroxide, improving the delignification efficiency of oxygen delignification. Among the group of activat...

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 ...

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 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 ...

The objective of this study was to evaluate different pretreatment methods prior to oxygen delignification on extractives removal and O-delignification selectivity. Four different pretreatment methods were used including ultrasonic treatment, hot water soaking, soda addition-preheating, and applying a high-shear mechanical pretretament. Acacia mangium and mixed hardwood (MHW) kraft pulps were u...

Soaking aqueous ammonia (SAA) pretreatment of corn stover was carried out at three temperatures (30, 50, and 70 oC) and three concentrations of ammonia solution (5, 15, and 25 wt.%). The delignification kinetic model, based on three first-order reactions, was applied to describe the kinetic behavior of lignin removal from corn stover during SAA pretreatment. The first, second, and third terms w...

Two types of pure cellulose, Avicel PH-101 and Whatman filter paper, were treated with an acid-chlorite delignification procedure in the presence of varying amounts of incorporated lignin, and the molecular weight distributions and degrees of polymerization (DP) of derivatized cellulose were determined by gel permeation chromatography (GPC). Avicel samples with 0% added lignin showed a DP reduc...

Common metrics for evaluating the efficiency of oxygen delignification include the kappa number and Klason lignin content. As a change in xylan content often leads to a change in HexA content, the kappa number must be corrected for the HexA contribution before evaluating the degree of oxygen delignification when trying to understand the process in detail. Questions could also be raised about th...

The formation of oxalate during oxygen delignification causes a number of operational problems in pulp and paper mills. In this work, the oxygen delignification of wheat straw pulp was carried out under various conditions and the concentration of resulting oxalate in the effluent was determined. The experimental results show that the amount of oxalate in the effluent was closely related to the ...