ISOLATION OF RICE HUSK OIL AND PREPARATION OF FATTY ACID MONOGLYCERIDES

Abstract

Rice husk, a widespread by-product of agro-industrial production, contains residual vegetable oils rich in unsaturated fatty acids. In this study, an eco-friendly and efficient strategy is presented for converting rice husk biomass into monoglycerides — compounds of significant industrial relevance. The process began with extraction of the raw material in a semi-automatic Soxhlet apparatus (ASV-6M) using ethyl acetate, which demonstrated the highest efficiency among six tested solvents, providing an oil yield of up to 2.82%. The obtained oil was subjected to catalytic glycerolysis under moderate pressure and temperature conditions (220 °C, 4 h) in the presence of potassium hydroxide, resulting in approximately 68.87% monoglyceride formation. Product purification was carried out by a two-step method: crystallization in an acetone–water system followed by column chromatography on silica gel, which enabled isolation of monoglycerides with a purity of up to 93%. Structural and compositional analyses were performed using gas chromatography–mass spectrometry (GC–MS) and infrared (IR) spectroscopy, which confirmed the presence of key esters — monoglycerides of palmitic and oleic acids. Mass spectrometry data confirmed molecular weights consistent with the structures of the monoglycerides, while the IR spectra revealed characteristic absorption bands corresponding to ester and hydroxyl functional groups.