Effect of the Interactions between Oppositely Charged Cellulose Nanocrystals (CNCs) and Chitin Nanocrystals (ChNCs) on the Enhanced Stability of Soybean Oil-in-Water Emulsions

Chitosan particles modulate the properties of cellulose nanocrystals through interparticle interactions: Effect of concentration

The physical and chemical properties of cellulose nanocrystals (CNC) were regulated by physical crosslinking with chitosan particles (CSp). At a fixed concentration (0.5 wt%) of CNC, varying CSp concentration (0.02-0.5 wt%) influenced the morphologies and chemical properties of the obtained complex particles (CNC-CSp). The results of Fourier transform infrared spectroscopy (FTIR) and zeta potential confirmed the electrostatic and hydrogen bonding interactions between CSp and CNC. At a low CSp concentration (0.02-0.05 wt%), the charge shielding effect induced the formation of particle aggregation networks, thus showing increased viscosity, turbidity and size (153.4-2605.7 nm). At a higher CSp concentration (0.1-0.5 wt%), the hydrogen bonding interaction promoted CSp adsorption onto the surface of CNC, thus facilitating the dispersion of CNC-CSp due to electrostatic repulsion caused by surface-adsorbed CSp. In addition, CSp improved the thermal stability, hydrophobicity (41.87-60.02°) and rheological properties of CNC. Compared with CNC, CNC-CSp displayed a better emulsifying ability and emulsion stability, in which CSp could play a dual role (i.e., charge regulator and stabilizer). This study suggests that introducing CSp can improve the properties and application potentials of CNC as food colloids.

Adsorptive properties and on-demand magnetic response of lignin@Fe3O4 nanoparticles at castor oil-water interfaces

Lignin@Fe₃O₄ nanoparticles adsorb at oil-water interfaces, form Pickering emulsions, induce on-demand magnetic responses to break emulsions, and can sequester oil from water. Lignin@Fe₃O₄ nanoparticles were prepared using a pH-induced precipitation method and were fully characterized. These were used to prepare Pickering emulsions with castor oil/Sudan red G dye and water at various oil/water volume ratios and nanoparticle concentrations. The stability and demulsification of the emulsions under different magnetic fields generated with permanent magnets (0-540 mT) were investigated using microscopy images and by visual inspection over time. The results showed that the Pickering emulsions were more stable at the castor oil/water ratio of 50/50 and above. Increasing the concentration of lignin@Fe₃O₄ improved the emulsion stability and demulsification rates with 540 mT applied magnetic field strength. The adsorption of lignin@Fe₃O₄ nanoparticles at the oil/water interface using 1-pentanol evaporation through Marangoni effects was demonstrated, and magnetic manipulation of a lignin@Fe₃O₄ stabilized castor oil spill in water was shown. Nanoparticle concentration and applied magnetic field strengths were analyzed for the recovery of spilled oil from water; it was observed that increasing the magnetic strength increased oil spill motion for a lignin@Fe₃O₄ concentration of up to 0.8 mg mL^-1 at 540 mT. Overall, this study demonstrates the potential of lignin-magnetite nanocomposites for rapid on-demand magnetic responses to externally induced stimuli.