Hybrid nanocellulose-based foams are a desirable class of low-density and porous materials for their potential in many applications. This study aims at characterizing and understanding the structure-properties relationship of four foam formulations prepared from combinations of cellulose nanofibrils (CNF), cellulose nanocrystals (CNC), and kaolin-microfibrillated cellulose composite. All the foams were crosslinked with a polyamide-epichlorohydrin crosslinker (Polycup) to impart stability under wet conditions without additional functionalization. Foams containing 25 wt% kaolin exhibited excellent shape recovery promoted by a higher load of crosslinker (5 wt%), and superior compressive properties. The addition of CNC at 33.3 wt% and 50 wt% did not seem to enhance the properties of the foam and also reduced the specific surface area. A preliminary comparative study between the four tested formulations was conducted to assess the feasibility of the foam as an adsorbent of methylene blue dye.

The application and optimal operation of nanoparticle adsorbents in fixed-bed columns or industrial-scale water treatment applications are limited. This limitation is generally due to the tendency of nanoparticles to aggregate, the use of non-sustainable and inefficient polymeric resins as supporting materials in fixed-bed columns, or low adsorption capacity. In this study, magnesium-doped amorphous iron oxide nanoparticles (IONPs) were synthesized and immobilized on the surface of cellulose nanofibrils (CNFs) within a lightweight porous aerogel for arsenic removal from water. The IONPs had a specific surface area of 165 m² g⁻¹. The IONP-containing CNF aerogels were stable in water and under constant agitation due to the induced crosslinking using an epichlorohydrin crosslinker. The adsorption kinetics showed that both As(III) and As(V) adsorption followed a pseudo second-order kinetic model, and the equilibrium adsorption isotherm was best fitted using the Langmuir model. The maximum adsorption capacities of CNF-IONP aerogel for As(III) and As(V) were 48 and 91 mg As g-IONP⁻¹, respectively. The optimum IONP concentration in the aerogel was 12.5 wt.%, which resulted in a maximum arsenic removal, minimal mass loss, and negligible leaching of iron into water.

New methods of oil-water separation are needed as industrialization has increased the prevalence of oil-water mixtures on Earth. As an abundant and renewable resource with high oxygen and grease barrier properties, mechanically refined cellulose nanofibrils (CNFs) may have promising applications for oil-water separations. The unbleached form of these nanofibrils, lignin-containing CNFs (LCNFs), have also been found to display extraordinary barrier properties and are more environmentally friendly and cost-effective than CNFs. Herein, both wet and dry LCNF-modified filter papers have been developed by coating commercial filter paper with an LCNF suspension utilizing vacuum filtration. The LCNF-modified filters were tested for effectiveness in separating oil-water emulsions, and a positive relationship was discovered between a filter’s LCNF coat weight and its oil collection capabilities. The filtration time was also analyzed for various coat weights, revealing a trend of high flux for low LCNF coat weights giving-way-to predictions of a coat weight upper limit. Additionally, it was found that wet filters tend to have higher flux values and oil separation efficiency values than dry filters of the same LCNF coat weight. Results confirm that the addition of LCNF to commercial filter papers has the potential to be used in oil-water separation.