Green liquor extraction of hemicelluloses from southern pine in an Integrated Forest Biorefinery

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

“…However, when pretreatments were performed at a higher green liquor dosage, such as 3%, more wood was preserved (at a dosage of 3%, wood losses were in the region of only 12% to 18%). The higher wood loss at a lower dosage may be caused by the induced effects of hot-waterlike pre-treatments, which lead to the excessive dissolution of carbohydrates (Yoon et al 2010;Tunc et al 2010;Tunc and Van Heiningen 2008a). On other hand, pre-treating wood chips with green liquor prior to kraft pulping has been shown to stabilize carbohyd-rates towards the peeling reaction (Ban et al 2003b;Olm et al 1996), thus reducing yield loss in the subsequent pulping process.…”

“…Hemicellulose pre-extraction from hardwood chips using various alkaline solutions combined with pulp production has been investigated previously (Helmerius et al 2010;Sixta and Schild 2009;Yoon and Van Heiningen 2010;Jin et al 2010). However, considering a number of factors such as investment and operational costs and compatibility with the existing kraft process, applications of some of the alkaline solutions are limited.…”

“…In order to maximize the hemicellulose yield (in a pure polymeric form) with minimal wood yield loss, a pre-treatment process resulting in a near-neutral pH has been proposed (Ladisch et al 2005;Yoon and Van Heiningen 2010;Zheng et al 2009). Maintaining a near-neutral pH prevents excessive carbohydrate hydrolysis (Ladisch et al 2005;Mao et al 2008).…”

Chemometric Study on Alkaline Pre-treatments of Wood Chips Prior to Pulping

“…Of these alternatives, the alkaline extraction of wood chips is the most promising when combined with an existing industrial alkaline pulping process (Yoon et al 2011;von Schenck et al 2013), as it reduces the cooking times and the need for alkali charge in the subsequent pulping process. In addition, green and white pulping liquors can be used for pre-treatments (Walton et al 2010;Yoon and van Heiningen 2010). However, as in chemical pulping, the reaction mechanisms of alkaline pre-treatments are extremely complex, unselective, and not fully understood.…”

Improvements in Pulp Properties by Alkali Pre-Extraction and Subsequent Kraft Pulping With Controlling H-Factor and Alkali Charge

“…This is usually called 'autohydrolysis', and there have been several studies about its effects on the chemical composition of wood chips (Caparrós et al 2007;Leschinsky et al 2009). Pre-extraction using hot water causes acidic conditions due to the release of acetic acid formed during autohydrolysis of the acetyl groups in the hemicelluloses (Song et al 2008;Tunc and van Heiningen 2008;Yoon and van Heiningen 2008b), and this acidity may accelerate the degradation of the cellulose at high temperatures, resulting in a significant loss in the pulp yield (Yoon et al 2010). The pulp yield is related to productivity and economy, and a decrease in the pulp yield is disadvantageous to any kraft pulp mill.…”