Assessing the experimental investigation of milk thistle oil for biodiesel production using base catalyzed transesterification

• Biodiesel production from non edible seeds of milk thistle species.
• High percentage of oil extraction (26.14%) and biodiesel yield (92%).
• Reduction in FFA contents via esterification 0.56 mg KOH/g – 0.06 mg KOH/g.
• Quantification analysis of biodiesel using GC, 1H NMR, 13C NMR, FT-IR and AAS.
• Fuel properties comparison with ASTM D6751 and EN 14214 standards.

In the present research work, non edible oil source milk thistle (Silybum marianum (L.) Gaert) plant was investigated for biodiesel production. The extracted crude oil was 26.14% of the total seed dry weight. The free fatty acid content of oil was reduced from 0.56 mg KOH/g to 0.06 mg KOH/g by esterification before the synthesis of biodiesel. The highest conversion percentage of biodiesel was achieved 89.51% and 87.42% using solid base catalyst sodium hydroxide (0.75%) and potassium hydroxide (1.0%), respectively. The protocol for experiment was adjusted as follow: temperature (60 °C); time of reaction (2 h), steering (600 rpm) and the oil molar ratio was fixed 1:6. Qualitatively, the prepared biodiesel was quantified by GC chromatography, 13C & 1H NMR (Nuclear Magnetic Resonance), AAS and FT-IR spectroscopy. The fuel properties of biodiesel were tested and compared with ASTM D6751 and EN 14214 standards.