Lanoline purification by selective extraction of pesticides using supercritical CO2

The efficiency of supercritical carbon dioxide for the selective removal of the more important pesticides from commercial lanoline was studied. Lanoline solubility values from 0.03 to 2.50 mg/g CO2 were obtained, corresponding to CO2 densities from 498.4 to 857.3 kg/m3, respectively. The original lanoline showed the following pesticide profile: diazinon 66 ppm, methyl-pirimifos 4.6 ppm and ethion 140 ppm. By an extraction carried out at 25 MPa and 45 °C, using a mass ratio solvent to substrate of 19.5 g CO2/mg lanoline, only 3.4% of lanoline was co-extracted and the pesticide concentrations were reduced to 0.47 ppm for diazinon, less than 20 ppb for methyl-pirimifos and 0.2 ppm for ethion.These results shows that supercritical CO2 is a very convenient solvent for the selective extraction of the main pesticides from lanoline, without the occurrence of substantial lanoline losses during the process.