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

Area of Science:

• Materials Science
• Colloid and Surface Chemistry
• Biopolymer Science

Background:

• Cellulose microfibers (CMFs) and nanofibers (CNFs) are crucial biomaterials.
• Efficient flocculation is key for processing CMFs and CNFs.
• Natural polyelectrolyte complexes (PECs) offer sustainable flocculation solutions.

Purpose of the Study:

• To investigate the rheological properties of xylan-chitosan PECs.
• To elucidate the flocculation mechanisms of CMFs and CNFs using PECs.
• To determine the optimal PEC composition and dosage for effective flocculation.

Main Methods:

• Characterization of polyelectrolyte solutions (viscosity, c*, rheology, ζ-potential, size).
• Dynamic flocculation studies via viscosity measurements.
• Static flocculation analysis (gel point, floc size, ζ-potential).

Main Results:

• Xylan-rich PECs exhibited higher viscosity, size, and ζ-potential, with lower critical concentrations.
• All PEC solutions displayed non-Newtonian shear-thinning behavior.
• Effective flocculation of CMFs and CNFs was achieved at low PEC dosages (2-6 mg/g fiber).
• Optimal flocculation occurred at minimum gel points and maximum floc sizes.
• CNF suspensions required higher PEC dosages than CMF suspensions.

Conclusions:

• Xylan-chitosan PECs are efficient flocculants for cellulose nanomaterials.
• PEC composition significantly impacts rheological behavior and flocculation efficacy.
• Low dosages of PECs are sufficient for effective flocculation, indicating their potential in sustainable material processing.