Impregnation of cotton fabric with pyrethrum extract in supercritical carbon dioxide

This study discusses a possibility of cotton fabric impregnation with pyrethrum extract as a tick repellent in supercritical carbon dioxide. A solubility of pyrethrum extract in supercritical carbon dioxide has been determined at 35 and 40 degrees C and pressures ranging from 8 to 20 MPa. The highest solubility of 48.69 kg/m(3) was obtained at temperature of 35 degrees C and pressure of 20 MPa. Density -based equations of Chrastil, Adachi-Lu and del Valle-Aguilera were employed to correlate the experimental data. Based on the solubility data, conditions for the impregnation of cotton fabric were selected. Conditions at 40 degrees C and 8 MPa provided targeted quantities of the impregnated extract of 0.5% and 1% after 1 h and 2 h of the impregnation, respectively. The presence of pyrethrins on the cotton fabric's surface was confirmed by FTIR analysis. Repellent activity of both impregnated cotton fabrics (pyrethrum extract contents of 0.5% and 1%) was proven against ticks.