This study assesses the possibility of obtaining regenerated cellulose products (beads and lms) from eucalyptus sawdust dissolving pulps produced by non-conventional processes, compared with a commercial dissolving pulp as a reference. Eucalyptus sawdust dissolving pulps were obtained by soda pulping followed by two different TCF sequential bleaching processes OOpZ and OOp (where O is oxygen, Op is oxygen reinforced with hydrogen peroxide, and Z is ozone), followed by a cold soda extraction. The characterization of dissolving pulps involved alpha-, beta-and gamma-cellulose content, alkali solubility with 10 wt% (S 10 ), and 18 wt% NaOH (S 18 ) aqueous solutions, and degree of polymerization. Fock´s method was used to measure cellulose reactivity and the alkali solubility in a 9 wt% NaOH aqueous solution at -5 °C to evaluate the pulps dissolving capacity. Dissolving pulps presented high cellulose content (> 93 %, expressed as a-cellulose) and good reactivity (almost 84 %). The dissolving pulps were adequate raw materials for regenerated cellulose products (beads and lms) from two cellulose dissolution methods: direct dissolution in NaOH/urea and cellulose carbamate solution. The sequence OOpE (where E is an alkaline extraction) was determined to be a more economically feasible and straightforward process to produce dissolving pulp than OOpZE. The experimental pulps showed the expected characteristics of the dissolving pulp to obtain regenerated cellulose products. However, it is necessary to deepen the study of producing regenerated cellulose lms with enhanced mechanical properties from experimental dissolving pulps, solvents, coagulation, and regeneration conditions.
Regenerated cellulose beads were synthesized for supporting copper as the catalytic active site for environmental remediation reactions. Starting from a commercial dissolving pulp, RC beads were prepared from direct dissolution and both solutions of carbamate and viscose. Copper was added to the supports by a simple green method. The material characterization by FTIR, TGA, SEM and XPS confirmed the successful incorporation of copper in all the prepared supports. The degradation of emerging contaminants (ECs) in water by catalytic wet peroxide oxidation (CWPO) was selected as a reaction test. Phenol was adopted as the EC test molecule in the CWPO reaction at 70°C. The results evidenced that the cellulose regeneration route directly affects catalytic yields. The catalysts containing lower than 1 wt.% of copper converted more than 90% of phenol with almost 30% of total mineralization. The novelty and importance of preparing bead-shape catalysts with cellulose reside in the use of an economical, renewable and biodegradable support, and the simple separation of the structured catalyst from the heterogeneous solid/liquid reaction media.
This study assesses the possibility of obtaining regenerated cellulose products (beads and films) from eucalyptus sawdust dissolving pulps produced by non-conventional processes, compared with a commercial dissolving pulp as a reference. Eucalyptus sawdust dissolving pulps were obtained by soda pulping followed by two different TCF sequential bleaching processes OOpZ and OOp (where O is oxygen, Op is oxygen reinforced with hydrogen peroxide, and Z is ozone), followed by a cold soda extraction. The characterization of dissolving pulps involved alpha-, beta- and gamma-cellulose content, alkali solubility with 10 wt% (S10), and 18 wt% NaOH (S18) aqueous solutions, and degree of polymerization. Fock´s method was used to measure cellulose reactivity and the alkali solubility in a 9 wt% NaOH aqueous solution at -5 °C to evaluate the pulps dissolving capacity. Dissolving pulps presented high cellulose content (> 93 %, expressed as a-cellulose) and good reactivity (almost 84 %). The dissolving pulps were adequate raw materials for regenerated cellulose products (beads and films) from two cellulose dissolution methods: direct dissolution in NaOH/urea and cellulose carbamate solution. The sequence OOpE (where E is an alkaline extraction) was determined to be a more economically feasible and straightforward process to produce dissolving pulp than OOpZE. The experimental pulps showed the expected characteristics of the dissolving pulp to obtain regenerated cellulose products. However, it is necessary to deepen the study of producing regenerated cellulose films with enhanced mechanical properties from experimental dissolving pulps, solvents, coagulation, and regeneration conditions.
The influence of the enzyme addition point on fiber properties was analyzed by treating two industrial recycled pulp sampleswith and without industrial refiningwith a mixture of cellulases and hemicellulases. The effects of the enzyme treatment variablesenzyme dosage, time, and consistencyon the fiber properties were studied. The aim of this work was to improve the drainability and the recovery of the strength properties of recycled fibers. The properties of the pulps treated enzymatically and refined in a PFI mill were also evaluated. According to the statistical analysis, opposite effects on drainability were obtained by varying pulp consistency, enzyme dosage, and enzyme application point (i.e., before or after the industrial mechanical treatment). Drainability and strength properties increased when the enzymatic treatment was applied to the pulp without industrial refining, whereas no improvement was observed for pulp with industrial refining.
Palladium was incorporated into carboxymethylated cellulose fibers as a support, thereby becoming an efficient and stable catalyst for low temperature gas phase reaction. Thus, NO was used as test molecule of Greenhouse Gas to be catalytically reduced with hydrogen on an eco-friendly sustainable material containing palladium as the active site. Prior to the catalytic test, the catalysts were reduced with glucose as an eco-friendly reagent. The material characterization was performed by SEM-EDS, XRD, LRS, TGA and FTIR.The catalytic results showed that at 170°C, NO conversion was 100% with a selectivity of 70% to nitrogen. While NOX species were completely converted into N2 at temperatures higher than 180°C. The starting commercial material Solucell® was also studied, but its performance resulted lower than the ones of functionalized fibers.The use of this strategy, i.e., the functionalization of cellulose fibers followed by in-situ formation of metallic nanoparticles, can be further applied for the design of a wide range of materials with interesting applications for gas and liquid phase reactions under mild conditions.
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