EFFECT OF HOMOGENIZATION PRESSURE ON THE OBTAINING OF CELLULOSE MICRO/NANO FIBRILS. INTERACTION WITH A NATURAL COMPLEX.

BASTIDA, GABRIELA ADRIANA; GALVÁN, MARÍA V.; NÚRIA FIOL; QUIM TARRÉS; MARC DELGADO-AGUILAR; MIGUEL A. ZANUTTINI

Girona

Congreso; CIADICYP 2022 Iberoamerican Congress on Pulp and Paper Research; 2022

Riadicyp, LEPAMAP, Universidat de Girona, Ciadicyp

Cellulose-based materials such as cellulose nano/micro fibrilar (MNFCs) can be used in novel applications in various technological fields. The use of CNFs intended for the substantial improvement of paper properties is the one that promises the highest volume of consumption. In this work, the effect of the pressure of the homogenizer on the characteristics of the micro/nanofibrillar celluloses (CMNFs) obtained from a commercial bleached eucalyptus pulp (BEP) was evaluated. For this, a chemical pre-treatment was performed using oxalic acid at two concentrations: 25 wt.% and 50 wt.%, followed a mechanical pre-treatment using a PFI mill refiner at 10,000 revolutions. The fibrillation process was performed using a high-pressure homogenizer at 0.75 wt.% of consistency, with the following sequence: 2 passes at 300 bar, and then, 3 passes at 300, 600, and 900 bar. Therefore, six different CMNFs were obtained, which were characterized with measurements of nanofibrillation yield by centrifugation, transmittance at 800 nm, surface charges using z-potential and size by dynamic light scattering (DLS). The results show that when the pressure of the homogenizer increases and the concentration of oxalic acid (50 wt.%), the nanofibrillation yield, transmittance, and surface charges values of the CMNFs increase and the hydrodynamic diameter decreases. In addition, cationic polyelectrolyte complexes (PECs) were formed by addition the chitosan solution (CS) on xylan (X) solution, at pH 5.0, under continuous stirring and with a mass ratio CS/X of 20/80. The charge and size of the PECs were determined using a zetasizer nano. The results were +4.7 mV and 314.6 nm. Then, the colloidal interaction between CMNFs and PECs were analyzed by curves of turbidity and surface charges. Finally, the retention and drenability of CMNFs when it was added to recycled unbleached softwood fibers and different dosages of PECs was studied in a Britt Dynamic Drainage Jar system at pH 7,0 and 0.01N NaCl. It is desired to obtain high retention values of the CNFs with an acceptable drainage rate in the formation process, aspects that are critical in the application of CNF in paper.