Hemicellulose Extraction from South African Eucalyptus grandis using Green Liquor and its Impact on Kraft Pulping Efficiency and Paper Making Properties

Abstract

The feasibility of enhancing the efficiency of the kraft pulping operations while at the same time evolving the process into a biorefinery, and thus producing hemicelluloses together with paper products, was studied. Hardwood chips (Eucalyptus grandis) were pre-treated with green liquor prior to pulp production. At optimal pre-treatment conditions, the pH of the resulting extract was 7.8, the wood weight loss was 14%, and the hemicellulose extracted was almost 40 kg/ton of woodchips. In the subsequent kraft pulping, the resulting data revealed that the woodchips from which hemicellulose had been pre-extracted could be pulped much faster than woodchips pulped without hemicellulose extraction. As a result, to maintain the target kappa number, a 20% reduction in pulping chemicals was achievable. Hemicellulose pre-extraction led to a 10% reduction in black liquor solid contents. Moreover, the strength properties of the pulps produced with and without hemicellulose extraction were comparable. Industrial acceptance of this concept, however, still requires a more accurate understanding of the effect of specific mill operating conditions on mill energy balance. Careful economic assessment of the options for handling the calcium carbonate scale problem will also be required before the technology can be considered for implementation.

Ionic liquids and deep eutectic solvents for lignocellulosic biomass fractionation

“…28 This discovery was the basis for the first industrial Kraft process for the removal of lignin and hemicellulose from lignocellulosic biomass, to remain with cellulose fibres. 29,30 Nowadays, the Kraft pulping process is used in 80% of the world production of pulp. The wood chips are cooked using a mixture of white liquor and spent black liquor at the temperature of 150-180 °C.…”

Monitoring the Chemistry and Monosaccharide Ratio of Eucalyptus Dunnii Wood by near Infrared Spectroscopy

“…On the other hand, the higher ratio could be attributable to E. dunnii containing more glucomannan or a combination of both. Other hardwoods vary in mean glucose-to-xylose ratio, such as Liriodendron tulipifera (2.18), 48 E. globulus (2.79) 49 and E. grandis (4.20), 50 which are all closer to E. dunnii than L. styraciflua.…”

Chemical Pretreatments of Wood Chips Prior to Alkaline Pulping - A Review of Pretreatment Alternatives, Chemical Aspects of the Resulting Liquors, and Pulping Outcomes

“…The most profound negative effects include the reduced yield of pulp compared to the reference kraft cooks produced without pre-extraction, reduced refining response, and decreased strength (tensile and burst strengths) properties of the produced pre-hydrolysis kraft (PHK) pulps. Alkaline pretreatments in general have only very minor negative effects on modified pulping and pulp quality (Huang and Ragauskas 2013a,b;Johakimu and Andrew 2013;Vena et al 2013a,b) Applying a pretreatment stage prior to delignification has been extensively used in the manufacture of dissolving pulp. In general, dissolving pulp refers to a cellulose product having very high cellulose content (95% or higher) suitable for manufacturing of various cellulose derivatives, such as cellulose esters and ethers, viscose, and cellophane (Biermann 1996;Sixta 2006).…”