Acidic Deep Eutectic Solvents as Green and Reusable Catalyst for Emulsifier Synthesis

Abstract

Emulsifiers known as mono- and diglycerides (MDG) are produced when fatty acids are esterified with glycerol (glycerolysis of fatty acids) with the use of an acid catalyst. This work is the first to use non-toxic deep eutectic solvents (DES) as a green catalyst for palmitic acid glycerolysis. The effect of various reaction temperatures and catalyst loadings on the catalyst activity of acidic DES (mixtures of betaine hydrochloride and citric/propionic acid), and reusability test of the catalyst were studied. The reaction takes place at a palmitic acid to glycerol molar ratio of 1:6 at a stirring speed of 300 rpm, reaction temperatures of 120-180 °C, and catalyst loadings of 1-5 wt.% (based on palmitic acid). Conversion of palmitic acid tends to increase with the increasing in reaction temperature and catalyst loading. The highest reaction conversion reaching 90.3% and produce the monoglycerides emulsifier as much as 72.8%. In addition, this catalyst is also very effective for reuse.