Waste cooking oil as starting resource to produce bio-polyol - analysis of transesteryfication process using gel permeation chromatography

Abstract

This work presents a possibility of implementing Green Chemistry principles in the synthesis of bio-components. Five out of twelve principles have been highlighted taking into account the reagents used as well as the product analysis method and process monitoring. The influence of different contents of a catalyst (0.15−0.45 wt.%), transesterification agents (ethylene glycol, propylene glycol, diethylene glycol, glycerin and triethanolamine) as well as the reaction time and the properties of the bio-polyols on the transesterification process of used cooking oil (UCO) were analysed.In this work, gel permeation chromatography (GPC) was used for the first time to evaluate the yield of UCO transesterification into di- and monoglycerides as well as the reaction time. It was concluded that alcohols containing two primary hydroxyl groups were more reactive than alcohols containing three hydroxyl groups or two hydroxyl groups including one primary and one secondary group. The most reactive agent was triethanolamine and the transesterification reaction progress monitoring using gel permeation chromatography allowed us to complete the reaction in a time shorter by 75 %. In the case of glycerine, it was necessary to increase the temperature in order to increase the reaction yield. Selected physico-chemical properties: the density, viscosity, hydroxyl value, acid value, content of water as well as molecular weight and chemical structure of the bio-polyols based on UCO were studied too.