Biodiesel obtained from supercritical carbon dioxide oil of Cynara cardunculus L.

The present work evaluates the use of cardoon (Cynara cardunculus L.) seed oil as a renewable raw material for biodiesel production using an endogenous plant of the Mediterranean Flora. Cardoon seed oil was extracted using supercritical carbon dioxide (scCO2) with different densities. Depending on the employed extraction conditions and/or methods, different oil yields and compositions were obtained. As expected, higher scCO2 densities led to higher cardoon oil yields similar to the Soxhlet one. Two biodiesel synthesis reactions were performed to convert oil esters into fatty acid methyl esters: alkali-based transesterification and acid esterification followed by alkali-based transesterification. All the obtained biodiesel samples were chemically and physically characterized. Results showed that the two-step transesterification led to higher biodiesel yields as well as higher fatty acid methyl ester (FAME) contents. Moreover, other measured properties fulfilled, with a few exceptions, the specified EN14214 values.

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► Cardoon (Cynara cardunculus L.) seed oil is a renewable raw material for biodiesel production.
► Carbon dioxide is an alternative extraction solvent that leads to distinguished oil compositions.
► A two-step transesterification reaction led to higher biodiesel yields as well as higher FAME contents.