Properties of Cellulose Nanofibers Extracted from Eucalyptus and their Emulsifying Role in the Oil-in-Water Pickering Emulsions

Lilian S Martins,Márcia A Silva Spinacé,Ronaldo Gonçalves Dos Santos

doi:10.1007/s12649-021-01498-8

Lilian S Martins, Márcia A Silva Spinacé + Show 1 more

Open Access

https://doi.org/10.1007/s12649-021-01498-8

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Abstract

In this work, nanocellulose particles were obtained from eucalyptus fibers by high-pressure homogenization (CNF) and by high-intensity ultrasound (SCNF). The nanocellulose was applied as a solid emulsifier for soybean oil in water (O/W) emulsions. The adding of 0.25–1 wt.% of both CNF and SCNF produced stable O/W emulsions without conventional surfactants. SCNF emulsions showed the highest stability and displayed the narrowest size distribution. Zeta potential values (− 40 to − 70 mV) indicated an electrical barrier to the droplet coalescence. The rheological behavior of O/W emulsions stabilized with CNF and SCNF was described by the Herschel-Buckley model. O/W emulsions produced with nanocellulose particles behave as shear thinning fluid, and their behavior index ranged from 0.33 to 0.68. Both CNF and SCNF emulsions displayed maximum yield stress at a particle concentration of 0.5 wt.% and 0.75 wt.%, respectively. Besides, the prepared O/W emulsions using 0.5 to 1.00 wt.% CNF or SCNF did not showed phase separation until 30 days of rest. The data point out to the feasibility of using nanocellulose as a natural emulsifier, which can replace conventional surfactants.

Highlights

Biomass-derived products have been pointed out as promising substitutes to fossil products in a variety of applications
cellulose nanofibers (CNF) and sonicated cellulose nanofibers (SCNF) that were submitted to the high-pressure homogenizer (HPH) and high-intensity ultrasound (HIUS) process, showed nanofibers of cellulose with random orientation, as shown in Figure 1a and b
It was not possible to determine the surface tension of the 1 wt.% of SCNF suspension because its high viscosity avoids the suspension droplet insertion into the small opening-diameter syringe. These results indicate a higher surface activity for the sonicated sample (SCNF), which is probably related to the SCNF smaller diameter and higher hydrophilicity that would result in a more adequate surface arrangement and better coverage of the surface area

Summary

Introduction

Biomass-derived products have been pointed out as promising substitutes to fossil products in a variety of applications. Lignocellulosic biomass has a high potential to originate valuable products, because of its intensive energy content. Cellulose extracted from lignocellulosic biomass has found valuable applications, such as the production of nanoparticles with industrial usage. Cellulose nanoparticles have been applied as solid colloidal particles, which could be used as a special type of surface-active agents in emulsion stabilization [4,5,6]. Dispersed liquid systems stabilized by solid particles are termed Pickering emulsions. The particles used in the Pickering emulsions include colloidal silica particles [8], carbon nanotubes [19 9], cyclodextrin [10], poly(lactic acid) microspheres [11] and cellulosic material with at least one dimension in the nanometer scale or nanocellulose [12, 5]

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