IMAM   24519
INSTITUTO DE MATERIALES DE MISIONES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Producción de CMF como alternativa de valorización del aserrín de eucalyptus en un esquema de biorrefinería
Autor/es:
IGLESIAS, MARÍA CELESTE; AREA, MARIA CRISTINA; EHMAN, NANCI VANESA; VEGA, BEATRIZ; VALLEJOS, MARÍA EVANGELINA; FELISSIA, FERNANDO ESTEBAN; PERESIN, SOLEDAD
Reunión:
Workshop; Workshop: Nanocelulosa y nanomaeteriales a partir de recursos agroforestales; 2021
Resumen:
This work evaluates microfibrillated cellulose production from an eucalyptus sawdust pulp (MFCes), obtained by a sequence involving a soda treatment and oxidative bleaching, to be included in a biorefinery scheme. Eucalyptus sp. sawdust, obtained from a sawmill-carpentry, was treated with 22% NaOH on oven-dry wood (O.D.), with a liquid/solid ratio of 6/1, at 170°C, for 60 min. The pulp was bleached by oxidative treatments using an O-Op sequence (oxygen and oxygen-H2O2). Microfibrillated cellulose elaborated from a commercial eucalyptus, elemental chlorine-free bleached (ECF) kraft pulp (MFCcp), was used as a reference. Both pulps, at 2% consistency and pH 7, were mechanically fibrillated using a Supermasscolloider friction grinder MKZA10-15J (Masuko Sangyo Co.). The degree of fibrillation was assessed by the determination of transmittance, turbidity, and viscosity at 0.5% consistency. Degree of polymerization, crystallinity, surface charge by cationic demand, Fourier Transform Infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and surface free energy (SFE), were also performed. Both pulps achieved a similar degree of fibrillation by mechanical treatment using two-disc sizes and different gaps (MFCes: 9 passes and MFCcp: 10 passes). The fibrillation degree was similar for both MFC suspensions. The transmittance and turbidity values were 24.8% and 419 NTU for the MFCes and 21.9% and 495 NTU for the MFCcp. Transmittance values were lower than those obtained with MFC produced by chemical pretreatment (TEMPO oxidation) and colloidal grinder but similar to that of MFC made by a disk refiner. The rheological behavior of both MFC was similar; the samples showed a thixotropic behavior and reached a constant viscosity at 12 rpm. The degree of polymerization was 800 and 1151 for the MFCes and MFCcp, respectively. The cristallinities were 64.0% and 58.0% for MFCcp and MFCes respectively. The decrease in crystallinity in the MFCes sample can be due to the oxidative bleaching treatment, which mainly degrades the amorphous fractions such as the hemicelluloses. The SFE was 41.4% for the MFCes and 41.9% for the MFCcp. The surface charge was higher for the first (166.4 µeq/g) than that of the second MFC (132.5 µeq/g). The thermal degradation profiles of the MFC showed that most degradation events occur from 250°C to 350°C corresponding to the degradation of cellulose (up to 350°C) and hemicelluloses (up to 273°C). However, these values were lower than thermal degradation occurred in pulps (about 284°C to 376°C for eucalyptus sawdust pulp and 290°C-383°C for commercial eucalyptus pulp). The residual masses at 600°C were 21.7% and 19.8% for MFCes and MFCcp, respectively. In terms of properties, the obtained results allow concluding that it is possible to produce MFC from eucalyptus sawdust processed by a soda treatment and oxidative bleaching, adequate to a small scale biorefinery scheme.