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| Authors: | Mocchiutti, Paulina |
| Title: | Improvements in The Papermaking Properties of Lignified Recycled Fibers by Application of Enzymatic and Chemical Oxidative Treatments. Advancements in the Knowledge of their Superficial Characterization |
| Keywords: | superficial acid groups / laccases / ozone / unbleached pulp / papermaking properties / |
| Abstract: | The effects of the application of enzymatic and chemical oxidative treatments on unbleached recycled softwood kraft pulps were studied with the aim of improving their papermaking properties and extending their possibilities of application. For the enzymatic treatments, the laccase-mediator system (LMS) was used. The laccases were isolated from the Trametes hirsuta fungus and the mediator used was 1-hydroxybenzotriazole. It was found that the treatments produced a slight reduction in the kappa number in parallel to an increase in the light absorption coefficient showing the oxidative effect of the enzymes on this kind of pulps. The freeness of the whole pulp increased, but the papermaking properties were not modified or decreased. The amount of carbonyl and carboxylic acid groups in the oxidized lignin of the fibrous fraction increased and consequently the tensile strength also increased. Ozone was used for the oxidative chemical treatments, which increased the tensile strength of the whole pulp and the fibrous fraction. Nevertheless, the freeness decreased. Ozone reduced the kappa number and the amount of insoluble lignin in acid medium, indicating that the oxidized lignin was solubilized. In this work, the polyelectrolyte adsorption method, necessary to determine the content of the superficial acid groups of the cellulose fibers, was optimized. An equation was proposed that fits the experimental isotherms and allows obtaining more precise results. |
| URI: | http://bibliotecavirtual.unl.edu.ar:8180/tesis/handle/1/48 |
| Date: | 22-Mar-2007 | | Advisor: | Zanuttini, Miguel Ángel Mario | | Co-Advisor: | Pereira Ramos, Luiz | | Sponsorship: | Agencia Nacional de Promoción Científica y Tecnológica, Consejo Nacional de Investigaciones Científicas y Técnicas, Fundación Antorchas, Universidad Nacional del Litoral |
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