Liquid and Supercritical CO2 Extraction of Pyrethrins from Chrysanthemum Cinerariaefolium (Trev.) Bocc: Yield and Purity in Function of Extraction Conditions. Kinetic Study of Extraction

摘要

Pyrethrins are characterized by a strong pesticide effect, that can be attributed mainly to the compounds pyrethrins I and II (PI and PII) The interest for compounds of natural origin showing a pesticide effect is growing fast, due to problems correlated with the use of synthetic compounds, that is, build up in the environment, development of resistance in target species, mammalian toxicity and residues on treated crops. The use of pyrethrins, on the contrary, doesn't involve such detrimental effects, as they are labile once dispersed in the environment [1], and have a ratio (LD50 oral mammalian/LDso topical insects) that, for pesticides, is among the lowest [2] This work reports the experimental results obtained in a campaign of PI and PII extraction from dried pyrethrum flowers (Chrysanthemum incariaefolium ) using liquid (20 °C and 10 MPa) and supercritical carbon dioxide (40°C and pressure of 9, 16 and 25 MPa) Both PI and PII yield and their concentration in the extract (product purity) were determined as a function of extraction conditions, This set of experiments were carried out with a laboratory scale apparatus and the obtained results were ;ilso compared to the ones obtained by Soxhlet extraction To study the extraction kinetic, additional experiments were carried out at three different extraction conditions (9 Mpa and 40 C : 16 Mpa and 40°C; 20 Mpa and 55°C) with a pilot plant apparatus.