Surfactant-free cellulose filaments stabilized oil in water emulsions

Amir Varamesh,Gurminder Minhas,Steven L Bryant,Keith Gourlay,Jinguang Hu,Ragesh Prathapan,Qingye Lu,Ali Telmadarreie,Jia Li

doi:10.1007/s10570-021-04320-9

Amir Varamesh, Gurminder Minhas + Show 7 more

Open Access

https://doi.org/10.1007/s10570-021-04320-9

Copy DOI

Journal: Cellulose	Publication Date: Dec 2, 2021
Citations: 3	License type: cc-by

Affiliation: University of Calgary

Abstract

There has been significant interest over recent years in the production and application of sustainable and green materials. Among these, nanocellulose has incurred great interest because of its exceptional properties and wide range of potential applications, including in Pickering emulsions. However, the production cost of these cellulosic materials has limited their application. In this study, the capability of a new type of cheaper cellulosic material, cellulose filaments (CFs), in formulating stable oil in water Pickering emulsions was investigated and compared with three conventional nanocelluloses, namely cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs) and TEMPO-oxidized CNFs (TEMPO-CNFs). Results showed that CFs can provide stable surfactant-free emulsions over wide ranges of salt concentration (0–500 mM) and pH (2–10), as indicated by the near-constant oil droplet size and dewatering index of the emulsions. This is due to the ability of CFs to strongly adsorb to the oil and water interface, as evidenced by Cryo-SEM and visualized through labelled CFs with engineered carbohydrate-binding module (CBM2a) conjugated with green fluorescent protein (CBM2a-eGFP) under fluorescent microscopy. Compared to the emulsions stabilized by other types of nanocelluloses, the CF-stabilized emulsion demonstrated a larger average droplet size and comparable (with CNFs) or better (than CNCs and TEMPO-CNFs) stability, which is partially attributed to the higher viscosity of continuous phase in the presence of CFs. The results of this study demonstrate the use of CFs as a novel and cheaper cellulosic material for stabilizing emulsions, which opens the door to a range of markets from the food industry to engineering applications.Graphical abstract

Highlights

Emulsions are colloidal systems in which droplets of a liquid phase are dispersed in another liquid phase (Schramm 2014)
To compare the different nanocellulose materials in terms of their surface charge and size, zeta potential and dynamic light scattering measurements were performed at neutral pH (Table 1)
In contrast to Cellulose filaments (CFs), emulsions stabilized by Cellulose nanocrystals (CNCs) and TEMPO-cellulose nanofibrils (CNFs) showed significant coalescence and creaming even though they have smaller average droplets diameter

Summary

Introduction

Emulsions are colloidal systems in which droplets of a liquid phase are dispersed in another liquid phase (Schramm 2014). Depending on the dispersed and continuous phase, emulsions are primarily categorized into oil in water and water in oil wherein water forms the continuous and dispersed phase respectively (Schramm 2014). Stabilizers or emulsifiers are often used to form stable emulsions. Soluble surfactants and polymers are two conventional surface-active stabilizers that have been used for making stable emulsions (Jiang et al 2020). Conventional emulsions that are stabilized by either surfactants or polymers tend to show poor stability when exposed to change in pH, temperature or ionic strength. It has been demonstrated that the usage of surfactants and polymers can be prohibitively expensive for some processes (Khan et al 2018; Gonzalez Ortiz et al 2020; Shi et al.2020)

Objectives

Methods

Conclusion