Simultaneous extraction and separation of phorbol esters and bio-oil from Jatropha biomass using ionic liquid–methanol co-solvents

• Ionic liquid–polar co-solvent systems were used to extract jatropha kernel biomass.
• Ionic liquid co-solvents effectively extracted phorbol esters and bio-oil.
• The extracted phorbol esters remained soluble in the co-solvent.
• The extracted bio-oil separated to its own immiscible phase.
• The jatropha protein remained with the biomass after treatment, thus detoxified biomass has potential for use as animal feedstock.

This work evaluates the applicability of an ionic liquid–methanol co-solvent system to extract phorbol esters from jatropha biomass. The extracted phorbol esters readily solubilized into the co-solvent due to a shared amphiphilic nature. Methyl sulfate anion had superior performance relative to acetate anion, extracting and solubilizing higher quantities of phorbol esters. Compared to traditional methods which only extract phorbol esters, the co-solvent system simultaneously extracted and separated the bio-oil to its own separate immiscible phase and with no appreciable loss of protein – the majority of protein remaining with the biomass and only a small residual amount (∼1 mg/ml) solubilizing into the co-solvent. The optimum co-solvent concentration for simultaneous extraction of phorbol esters and bio-oil was determined to be 30 wt% IL and 70 wt% methanol. With respect to the extracted kernel biomass, the high proportion of protein (68–70%) and low phorbol esters (0.15 mg/g kernel) content suggested a high suitability as an animal feed.