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...

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...

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 ...

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 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...

The main challenge in the oxygen delignification process is the improvement of selectivity. To further understand the effect of the amount of hydroxyl radicals on the selectivity of oxygen delignification, in this work, the hydroxyl radicals were generated by the improved Fenton reaction system and were quantified by UV spectrophotometry. Antioxidants such as ascorbic acid were applied for the ...

INTRODUCTION There has been a steady increase in the use of oxygen delignification worldwide since the first commercial installation in South Africa in 1970 [1]. The degree of delignification achieved in the oxygen stage is ultimately limited by pulp strength considerations, and averages 40% delignification industrially [2,3]. With greater degrees of delignification, the oxygen delignification ...

Changes in the lignocellulosic composition of four hardwoods, i.e. Eucalyptus grandis camaldulensis (E. gc), E. grandis urophylla (E. gu), E. dunnii and E. nitens, were investigated during different delignification processes using confocal Raman spectroscopy, Cross-Polarization Magic Angle Spinning Carbon 13 Nuclear Magnetic Resonance (CP/MAS C-NMR) spectroscopy and Atomic Force Microscopy (AFM...

HYDROGEN PEROXIDE HAS ALWAYS been a technologically attractive oxidant to the pulp and paper industry, with its significance becoming increasingly important as environmental regulations become more stringent. Beyond its ease of handling and application, hydrogen peroxide is also a versatile and benign compound whose decomposition products are water and oxygen. Among its major drawbacks are its ...