The Solvent Extraction of Solids

Fluid extraction under pressure is similar to super critical fluid extraction, except normal solvents are employed and the extraction rate is increased by operating at elevated temperatures and pressures.

Figure 21 High Pressure Fluid Extraction Apparatus

A diagram of the apparatus used for high pressure fluid extraction is shown in figure 21.The extraction takes place in a heated extraction tube and the solvents, selected from a group of solvent reservoirs, is pumped into the extraction tube under pressure. When extraction is complete, the extract is drained into sample tubes and concentrated by evaporation. Extraction temperatures range from 100°C to 180°C at pressures that span from 1500 psi to 2000 psi. This method is used to extract herbicides and insecticides such as organo-phosphorus and organo-chlorine compounds from dried soil samples.