Hairy cationic nanocrystalline cellulose as a novel flocculant of clay.

Hypothesis: The present paper investigates, for the first time, the potential of cationic hairy cellulose nanocrystals (CNCC) to induce the flocculation of a model suspension of kaolinite. CNCC belong to a brand new family of nanocelluloses characterized for presenting a crystalline rod-like body and functionalized amorphous chains at both ends. Given that these chains can be easily tuned, these nanocelluloses present a high potential as fit-to-purpose flocculants.

Experiments: CNCC were produced through periodate oxidation, cationization and thermal treatment of cellulose. Flocculation was monitored by both photometric dispersion analysis and laser reflectance. Flocs were characterized by the determination of zeta potential, supernatant turbidity removal and optical microscopy. A recently developed machine learning random forest regression model was used to estimate fractal dimension (D) from chord length distribution data.

Findings: Although a high efficiency was achieved for CNCC dosages between 7.5 and 75 mg/g, the maximum floc size and the fastest flocculation were found near the isoelectric point (10-30 mg/g). Thus, CNCC acted through charge neutralization mechanism. The model used to estimate flocs D was found very successful to describe the flocculation process. The clay/CNCC flocs D values suggest a relation between floc conformation and CNCC dosage, presenting an opener structure when closer to the isoelectric point.