Characteristics of pickering emulsion stabilized by cellulose nanofibrils in different oil phase polarity

The properties and stability of the emulsion can be greatly influenced by changes in the polarity of the oil used in it. This is due to the characteristics of each emulsifier which has a certain compatibility with polar and non-polar oils or solvents. Here we describe the characteristics of an oil-in-water Pickering emulsion using cellulose nanofibrils (CNF) as a Pickering agent or stabilizer for emulsions with different oil phase polarities: Ethyl acetate, Toluene, and Hexane. The viscosity, distribution of droplet size, and creaming index were investigated to learn the effect of oil polarity on emulsion stability. The result showed that the emulsification process of the Pickering emulsion in all types of oil phase polarity is depends on the CNF concentration. CNF 2% indicates the most suitable concentration for all type of oil phase. The viscosity of Pickering emulsion increases with the decrease in the polarity of the oil phase. It was confirmed by the droplet size distribution of the emulsion, whereas the droplet size for the emulsion with lower oil phase polarity (hexane) was smaller than the droplet size for the emulsion with high polarity (ethyl acetate), about 4.3 µm and 7.67 µm respectively. The CNF was more suitable for non-polar solvents, as seen by the stability of hexane in water emulsion for 30 days of storage, which is better than Toluene and Ethyl Acetate. In addition, the difference in viscosity, droplet size, and creaming index of hexane in water are less than those of the others after storage, which shows better stability. Studying the interaction of the particle as a stabilizer with different oil phase polarity, we can easily alter the viscosity and stability of the Pickering emulsion based on the product concept and requirements.