title: Potential of hot water extraction of birch wood to produce high-purity dissolving pulp after alkaline pulping.
abstract: The potential of hot water extraction of birch wood to produce highly purified dissolving pulp in a subsequent soda-anthraquinone pulping process was evaluated. After intermediate extraction intensities, pulps with low xylan content (3-5%) and high cellulose yield were successfully produced. Increasing extraction intensity further decreased the xylan content in pulp. However, below a xylan content of 3%, the cellulose yield dramatically decreased. This is believed to be due to cleavage of glycosidic bonds in cellulose during severe hot water extractions, followed by peeling reactions during alkaline pulping. Addition of sodium borohydride as well as increased anthraquinone concentration in the pulping liquor increased the cellulose yield, but had no clear effects on pulp purity and viscosity. The low intrinsic viscosity of pulps produced after severe extraction intensities and soda-anthraquinone pulping corresponded to the viscosity at the leveling-off degree of polymerization, suggesting that nearly all amorphous cellulose had been degraded.
authors.affiliation: Department of Forest Products Technology, School of Chemical Technology, Aalto University, P.O. Box 16300, FI-00076 Aalto, Finland. marc.borrega@aalto.fi
authors.forename: Marc
authors.initials: M
authors.lastname: Borrega
authors.forename: Lasse K
authors.initials: LK
authors.lastname: Tolonen
authors.forename: Fanny
authors.initials: F
authors.lastname: Bardot
authors.forename: Lidia
authors.initials: L
authors.lastname: Testova
authors.forename: Herbert
authors.initials: H
authors.lastname: Sixta
mesh_terms: D000880:Anthraquinones; D029662:Betula / Q000737:chemistry*; D002482:Cellulose / Q000737:chemistry*; D006358:Hot Temperature; D006868:Hydrolysis; D008970:Molecular Weight; D012972:Sodium Hydroxide / Q000737:chemistry*; D014783:Viscosity; D014867:Water / Q000737:chemistry*; D014934:Wood / Q000737:chemistry*
chemical_list: D000880:Anthraquinones; D014867:Water; D012972:Sodium Hydroxide; D002482:Cellulose