Jatropha curcas L. oil extracted by switchable solvent N,N-dimethylcyclohexylamine for biodiesel production

Biodiesel, which is a renewable and environmentally friendly fuel, has been studied widely to help remedy increasing environmental problems. One of the key processes of biodiesel production is oil extraction fromoilseed materials. Switchable solvents can reversibly change from molecular to ionic solvents under atmospheric CO₂, and can be used for oil extraction. N, N-dimethylcyclohexylamine (DMCHA), a switchable solvent, was used to extract oil from Jatropha curcas L. oil seeds to produce biodiesel. The appropriate extraction conditions were:1:2 ratio of seedmass to DMCHA volume, 0.3-1mmparticle size, 200 r·min^-1 agitation speed, 60min extraction time, and 30℃ extraction temperature. The extraction ratio was about 83%. This solvent extracted the oil more efficiently than hexane, and ismuch less volatile. By bubbling CO₂ under 1 atmand 25℃ for 5 h, the oilwas separated, and DMCHA was recovered after releasing CO₂ by bubbling N₂ under 1 atmand 60℃ for 2 h. The residual solvent content in oil was about 1.7%. Selectivity of DMCHA was evaluated by detecting the protein and sugar content in oil. Using the oil with residual solvent to conduct transesterification process, the oil conversion ratio was approximately 99.5%.