Fatty acids recovery from vegetable oil wet sludge by supercritical alcoholysis

In the last decade the production of soybean and sunflower oil has greatly increased worldwide. Together with it, the market of the oil refining by-products, phospholipids sludge (wet gum) and distillates of the deodorizer (DDEO) is rapidly changing. In this work, we performed the direct alcoholysis of the phospholipids and oil enclosed in the wet gum using supercritical ethanol. A statistical design of experiments was carried out to determine the effect of temperature (280–320 °C), ethanol concentration (50–80 wt%), reaction time (20–50 min) and water content (51–2.4 wt%). In all the cases a complete conversion of the lipids was observed. After removal of volatile compounds, the reaction product contained a hexane insoluble solid substrate (around 25%) and an oily phase with more than 50 wt% of fatty esters.

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► FAEE from vegetable oils sludge have been successfully obtained by scEthanolysis.
► The temperature and ethanol concentration have a positive effect on the FAEE yield.
► High content of water in the raw material promotes the formation of free fatty acids.
► scAlcoholysis is a simple technology to recover valuable products from oily sludges.