title: Thermogravimetry study of xylanase- and laccase/mediator-treated eucalyptus pulp fibres.
abstract: Thermogravimetric analyses (TGA) was applied to study the effects of enzymatic bleaching of eucalyptus pulp with xylanase and a laccase-mediator system. The thermal degradation profile of the pulps was sensitive to the enzymatic treatments. Xylanase treatment produced an ordered and clean microfibril, whereas laccase oxidized surface cellulose chains and increased the amorphous (paracrystalline) cellulose content. In this case, pulp viscosity decreased from 972 to 859 mL/g and apparent pulp crystallinity calculated from TGA data decreased almost 50%. Alkaline extraction was necessary to recover pulp crystallinity and to remove oxidized lignin in the laccase-treated samples. TGA data allowed differentiating and quantifying crystalline and amorphous cellulose. This thermogravimetric approach is a simple method in order to monitor superficial changes in cellulosic microfibrils.
authors.affiliation: Chemical Engineering Department, Campus El Carmen, University of Huelva, 21071 Huelva, Spain. agustin.garcia@diq.uhu.es
authors.forename: Agustín G
authors.initials: AG
authors.lastname: Barneto
authors.forename: Cristina
authors.initials: C
authors.lastname: Valls
authors.forename: José
authors.initials: J
authors.lastname: Ariza
authors.forename: M Blanca
authors.initials: MB
authors.lastname: Roncero
mesh_terms: D002851:Chromatography, High Pressure Liquid; D043364:Endo-1,4-beta Xylanases / Q000378:metabolism*; D005052:Eucalyptus / Q000737:chemistry*; D042845:Laccase / Q000378:metabolism*; D010209:Paper; D018547:Plant Stems / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013818:Thermogravimetry / Q000379:methods; D014961:X-Ray Diffraction
chemical_list: D042845:Laccase; D043364:Endo-1,4-beta Xylanases