Flocculation of Cellulose Microfiber and Nanofiber Induced by Chitosan–Xylan Complexes

Authors:
Open Access
Publisher website
Google Scholar
Abstract
This study aims to provide a comprehensive understanding of the key factors influencing the rheological behavior and the mechanisms of natural polyelectrolyte complexes (PECs) as flocculation agents for cellulose microfibers (CMFs) and nanofibers (CNFs). PECs were formed by combining two polyelectrolytes: xylan (Xyl) and chitosan (Ch), at different Xyl/Ch mass ratios: 60/40, 70/30, and 80/20. First, Xyl, Ch, and PEC solutions were characterized by measuring viscosity, critical concentration (c*), rheological parameter, ζ-potential, and hydrodynamic size. Then, the flocculation mechanisms of CMF and CNF suspensions with PECs under dynamic conditions were studied by measuring viscosity, while the flocculation under static conditions was examined through gel point measurements, floc average size determination, and ζ-potential analysis. The findings reveal that PEC solutions formed with a lower xylan mass ratio showed higher intrinsic viscosity, higher hydrodynamic size, higher z-potential, and a lower c*. This is due to the high molecular weight, charge, and gel-forming ability. All the analyzed solutions behave as a typical non-Newtonian shear-thinning fluid. The flocculation mechanisms under dynamic conditions showed that a very low dosage of PEC (between 2 and 6 mg PEC/g of fiber) was sufficient to produce flocculation. Under dynamic conditions, an increase in viscosity indicates flocculation at this low PEC dosage. Finally, under static conditions, maximum floc sizes were observed at the same PEC dosage where minimum gel points were reached. Higher PEC doses were required for CNF suspensions than for CMF suspensions.
Funding Information
  • Agencia I+D+i (PICT 2018 Nº 4410, PICT 2019 Nº 03246, PICT 2020 Nº 02920, Tipo II-Nº 50620190100135LI, CON-FUTURO-ES (PID2020-113850RB-C22), VALORCON-NC (PDC2021-120964-C22))
  • CAI+D 2020 PI (PICT 2018 Nº 4410, PICT 2019 Nº 03246, PICT 2020 Nº 02920, Tipo II-Nº 50620190100135LI, CON-FUTURO-ES (PID2020-113850RB-C22), VALORCON-NC (PDC2021-120964-C22))
  • CONICET (PICT 2018 Nº 4410, PICT 2019 Nº 03246, PICT 2020 Nº 02920, Tipo II-Nº 50620190100135LI, CON-FUTURO-ES (PID2020-113850RB-C22), VALORCON-NC (PDC2021-120964-C22))
  • Ministerio de Ciencia e Innovación (PICT 2018 Nº 4410, PICT 2019 Nº 03246, PICT 2020 Nº 02920, Tipo II-Nº 50620190100135LI, CON-FUTURO-ES (PID2020-113850RB-C22), VALORCON-NC (PDC2021-120964-C22))

This publication has 55 references indexed in Scilit: