Adsorption and Assembly of Cellulosic and Lignin Colloids at Oil/Water Interfaces

Abstract

The surface chemistry and adsorption behavior of submicrometer cellulosic and lignin particles have drawn wide-ranging interest in the scientific community. Here, we introduce their assembly at fluid/fluid interfaces in Pickering systems and discuss their role in reducing the oil/water interfacial tension, limiting flocculation and coalescence, and endowing given functional properties. We discuss the stabilization of multiphase systems by cellulosic and lignin colloids and the opportunities for their adoption. They can be used alone, as dual components, or in combination with amphiphilic molecules for the design of multiphase systems relevant to household products, paints, coatings, pharmaceutical, foodstuff, and cosmetic formulations. This invited feature article summarizes some of our work and that of colleagues to introduce the readers to this fascinating and topical area.

Spherical lignin particles: a review on their sustainability and applications

“…Whereas spherical lignin particles have not yet been applied as a dispersant for mineral suspensions, there has been many demonstrations of their applicability as Pickering emulsifiers to stabilize oil-in-water (O/W) emulsions. 84 Such multiphase systems have potential for applications in many technical fields, but mostly in cosmetics, paints, food, and agriculture. Pickering emulsions usually display longer lifetime when compared to surfactant-based emulsions, which is due to the higher resistance against droplet coalescence induced by the particles adsorbed at the O/W interface.…”

Strategies for structuring diverse emulsion systems by using wood lignocellulose-derived stabilizers

“…There are numerous possibilities for converting lignin into chemicals and derivatives. One interesting approach to developing new materials is preparation of lignin particles, as reviewed by Beisl et al 121 and Bai et al 122 For example, alkaline lignin extracted from the residues resulting from furfural production is soluble in basic water. In acidic conditions, lignin becomes insoluble and forms particles that are an effective emulsifier for o/w Pickering emulsions.…”

“…A surface active emulsifier is usually first needed to reduce droplet size. 122 Viscosity optimization is essential for many common industrial applications. To facilitate processing of certain products, such and paints 14 and heavy crude oil, 67 low viscosity is desired, so interfacial stabilization of emulsions is preferred over viscosity increase.…”

Centrifugal fractionation of softwood extracts improves the biorefinery workflow and yields functional emulsifiers

“…In this case, oil-in-water or water-in-oil Pickering emulsions are formed. 32,33 Besides the extraction and purification methods, the particle preparation method also greatly affects the emulsifying performance of lignin particles. 32 Moreover, stable oil-in-water emulsions can be obtained using lignincontaining food grade materials such as cocoa particles 34 and spent coffee grounds.…”

“…32,33 Besides the extraction and purification methods, the particle preparation method also greatly affects the emulsifying performance of lignin particles. 32 Moreover, stable oil-in-water emulsions can be obtained using lignincontaining food grade materials such as cocoa particles 34 and spent coffee grounds. 35 It is evident that hemicelluloses and lignin, extracted using, for example, the PHWE method, can be used to increase the sustainability of the food chain because woods can be grown on, for example, non-arable land, introducing a wood-to-food approach.…”