ENHANCING KAOLIN FLOCCULATION BY ADJUSTING SIZE AND CHARGE DENSITY OF CATIONIC CELLULOSE NANOFIBRILS

The search for more environmentally friendly water treatments is crucial for a future with drinking water available. Nanocellulose can ally in water treatment since it is renewable, biodegradable, and abundant. Several studies have addressed using nanocellulose-based materials as adsorbents and filtration membranes, but only a few works have studied nanocellulose suspension as a flocculant.¹ Considering that the coagulation-flocculation process is simple, cost-effective, and widely used in water treatment plants, it is of great importance to apply compounds that are more sustainable than the flocculants currently used. This study investigated the ability of positively charged cellulose nanofibrils to flocculate model suspensions of contaminated water (kaolin suspension). The influence of charge density and size of the nanofibrils were also evaluated. The flocculation performance was assessed through UV-vis spectrophotometry (750 nm) and visual inspection. Our results demonstrated that all cationic cellulose nanofibrils (CCNFs) can interact with negatively charged kaolin particles and promote their flocculation. Phase separation and stability depended on the charge density, size, and amount of nanofibrils. Smaller and highly charged CCNFs were more efficient in floc formation than lowly charged and larger fibrils. CCNF with the highest charge density and smaller size, requested 0.5 mgL^-1 to promote effective flocculation (%T>85%). These findings demonstrated the potential of optimizing fibril characteristics to enhance flocculation performance, improving the environmental friendliness of wastewater treatment.