Refining of birch kraft pulp before or during xylanase treatment – effect on carbohydrate release and retention behavior OPEN ACCESS
Katja Lyytikäinen and Kaj Backfolk
The effects on resulting pulp properties when refining never-dried bleached birch kraft pulp before or during treatment with a monocomponent endo-1-4-β-xylanase were studied. Moreover, the subsequent effects on first pass, filler, alkyl ketene dimer (AKD), and starch retention were determined in a dynamic papermaking environment. When the pulp was refined during the final stage of enzymatic hydrolysis but before initiating the heat-deactivation step, a much larger amount of xylan-based carbohydrates was released into the pulp filtrates than after xylanase treatment of the refined pulp. Atomic force microscopy (AFM) operated in tapping mode revealed that refining during xylanase treatment resulted in a more homogeneous fiber surface with respect to the surface topography, fibril orientation and diameter of surface microfibril aggregates than the xylanase treatment of refined pulp. When used as a fiber source in papermaking, all the xylanase-treated pulps showed lower retention levels, the highest retention losses being recorded for the pulps showing the largest amounts of dissolved carbohydrates in their filtrates. The observed changes in retention levels showed linear correlations with the cationic demand of the pulp filtrates.
Nordic Pulp & Paper Research Journal (NPPRJ) is an international scientific magazine covering science and technology for the areas of wood or bio-mass constituents, pulp and paper and including new fiber-based materials, recovery and by-products from pulping processes, bio-refining and energy issues. Articles meeting required scientific standards are accepted from any continent. ISSN: 0283-2631