EXPERIMENTAL-DESIGN APPROACH FOR THE OPTIMIZATION OF SUPERCRITICAL-FLUID EXTRACTION OF PYRALENE AND ALDRIN IN SOIL MATRIX

Characterisation and remediation of contaminated soils are crucial iss ues in environmental control. Extraction of pollutants with supercriti cal fluids is a competitive and viable technique on a laboratory scale and is of great interest for the treatment of contaminated soils in t he future. Extraction by supercritical fluids (CO2 or modified CO2) ha s been carried out on a standard soil (EUROSOIL 1), artificially pollu ted by organochloride compounds, i.e. pyralene and aldrin. A commercia lised extraction apparatus has been used in order to determine the opt imal operating conditions for quantitative extraction. A systematic ex traction study has been developed and interpreted according to the opt imal design method. Several parameters influencing extraction have bee n identified and studied: pressure, temperature, extraction flow-rate, type of extracting fluid, water content of soil. The percentage recov ery has been determined for each experiment. Linear regression of the resulting data has allowed the construction of a recovery response sur face, which indicates that high recovery can be obtained over a wide r ange of extraction conditions. (C) 1998 Elsevier Science Ltd. All righ ts reserved.