title: An improved TCF sequence for biobleaching kenaf pulp: influence of the hexenuronic acid content and the use of xylanase.
abstract: Enzymatic delignification with laccase from Trametes villosa used in combination with chemical mediators (acetosyringone, acetovanillone and 1-hydroxybenzotriazole) to improve the totally chlorine-free (TCF) bleaching of kenaf pulp was studied. The best final pulp properties were obtained by using an LHBTQPo sequence developed by incorporating a laccase-mediator stage into an industrial bleaching sequence involving chelation and peroxide stages. The new sequence resulted in increased kenaf pulp delignification (90.4%) and brightness (77.2%ISO) relative to a conventional TCF chemical sequence (74.5% delignification and 74.5% brightness). Also, the sequence provided bleached kenaf fibers with high cellulose content (pulp viscosity of 890 g·mL(-1) vs 660 g·mL(-1)). Scanning electron micrographs revealed that xylanase altered fiber surfaces and facilitated reagent access as a result. However, the LHBTX (xylanase) stage removed 21% of hexenuronic acids in kenaf pulp. These recalcitrant compounds spent additional bleaching reagents and affected pulp properties after peroxide stage.
authors.affiliation: Chemical Engineering Department, ETSEIAT, Universitat Politècnica de Catalunya, Colom 11, E-08222 Terrassa, Spain. Electronic address: gloria.andreu@upc.edu.
authors.forename: Glòria
authors.initials: G
authors.lastname: Andreu
authors.affiliation: Textile and Paper Engineering Department, ETSEIAT, Universitat Politècnica de Catalunya, Colom 11, E-08222 Terrassa, Spain.
authors.forename: Teresa
authors.initials: T
authors.lastname: Vidal
mesh_terms: D057919:Biological Oxygen Demand Analysis; D001709:Biotechnology / Q000379:methods*; D057886:Bleaching Agents / Q000494:pharmacology*; D002713:Chlorine / Q000737:chemistry*; D043364:Endo-1,4-beta Xylanases / Q000378:metabolism*; D006603:Hexuronic Acids / Q000032:analysis*; D031584:Hibiscus / Q000737:chemistry* / Q000187:drug effects*; D042845:Laccase; D008031:Lignin / Q000302:isolation & purification; D055454:Trametes / Q000201:enzymology; D014783:Viscosity; D014865:Waste Disposal, Fluid
chemical_list: D057886:Bleaching Agents; D006603:Hexuronic Acids; C095263:hexenuronic acid; D002713:Chlorine; D008031:Lignin; D042845:Laccase; D043364:Endo-1,4-beta Xylanases
keywords: Hexenuronic acids; Kenaf; Laccase-mediator system (LMS); TCF bleaching sequence; Xylanase