Crude glycerine purification by solvent extraction

MAQUIRRIAIN, MAIRA ALEJANDRA; NEYERTZ, CLAUDIA A.; QUERINI, CARLOS ALBERTO; PISARELLO, MARÍA LAURA

BRAZILIAN JOURNAL OF CHEMICAL ENGINEERING

BRAZILIAN SOC CHEMICAL ENG

Lugar: Sao Paulo; Año: 2021

0104-6632

In this work, a process to remove saponifable matter (fatty acid methyl esters (FAME), free fatty acids, mono-, di-, and tri-acylglycerides) from industrial crude glycerine samples is addressed. The extraction of these impurities with diferent solvents is analyzed in detail, using diethyl ether, methyl ter-butyl ether, FAME, toluene, hexanes, 1-butanol and 1-hexanol. Hexane and biodiesel were chosen as the main candidates in order to be used in this process. It was found that it is necessary to add water to the crude glycerine to efciently remove the saponifable matter. Water increases the polarity of the phase and favors the transference of the impurities to the non-polar phase, e.g. the hexanes. The use of FAME as extraction solvent requires the use of higher temperature than when using hexanes, higher levels of water addition, and pH adjustment before the extraction. The addition of 20 wt% of water, carrying out the extraction at 80 °C with a pH adjustment at 3, and separation by centrifugation represents a good set of process conditions in order to efciently extract the saponifable matter from crude glycerine. UV?Vis analysis proved to be very useful in following the purifcation process, while FTIR carried out directly on the glycerine has not enough sensitivity to follow the extraction.