Lignin-rich cellulose nanocrystals from coir fiber treated with ionic liquids: Preparation and evaluation as pickering emulsifier

Abstract

Lignocellulosic materials are promising sources of energy and biomaterials. In this context, the biomass from the mesocarp of the green coconut can be used to produce nanocellulose. For this purpose, this work proposed approaches for pretreatment of coconut biomass using protic ionic liquids (PILs), which are solvents that have specific characteristics and less environmental impact, followed by acid hydrolysis to obtain lignin-containing nanocellulose. Thus, three PILs were produced, and two pretreatment methodologies were evaluated. The results showed that, when using the ionic liquid 2-HEAA and Methodology B, there was a delignification of 17.4 %, a reduction of 14 % of hemicelluloses and a gain of 50.8 % of cellulose. Furthermore, acid hydrolysis provided a stable suspension of lignin-containing cellulose nanocrystals (zeta potential of −34.6 mV) with particles in the nanometer scale and more thermally resistant. When testing these lignin-containing cellulose nanocrystals as a stabilizer for oil-in-water emulsions, satisfactory results were obtained at a concentration of 0.50 %, which generated a stable emulsion for 14 days (−47.5 mV of zeta potential and mean diameter of 6.23 µm).