Natural deep eutectic solvents as green and homogeneous catalysts for the glycerolysis of stearic acid: Catalytic activity and kinetic studies

Abstract

Emulsifier as the mixture of monoglycerides (MG) and diglycerides (DG) is widely used in the food industry such as bakery products, margarines, dairy products, and confectionary. This emulsifier can be produced by glycerolysis of fatty acids using acid catalyst. In this work, natural deep eutectic solvent (NADES) was chosen as a catalyst in the glycerolysis of stearic acid due to greener and sustainable catalyst with advantages such as low vapor pressure, non-toxic, biodegradable, and easy to reuse. The catalytic activity of the NADES, kinetic constants and activation energies for the reaction were investigated. The reaction was carried out at agitation speed (300 rpm), catalyst concentration (5 wt%), reaction temperatures (120 °C, 150 °C and 180 °C) and reactant mole ratios (1:2, 1:4 and 1:6). Choline chloride-sorbitol NADES has highest catalytic activity on the glycerolysis of stearic acid. The kinetic calculation results using choline chloride-sorbitol NADES as a catalyst validated that the reaction was pseudo second order with an activation energy of 64.04 kJ∙mol−1, and a collision factor of 196,696 L∙mol−1∙min−1. This kinetics data will be useful for reactor design in industrial applications.

Keywords

• Glycerolysis
• Mono-diacylglycerol
• Natural deep eutectic solvents
• Stearic acid