Foaming properties of solvents for use in air-assisted solvent extraction

The air-assisted solvent extraction (AASX) concept uses a solvent-coated bubble to contact the organic and aqueous phases. Compared to conventional solvent extraction, a high contact area can be created using less solvent and the buoyancy provided by the air core promotes phase separation. Solvent-coated bubbles are produced by forming a foam. The foam is injected through a capillary and a solvent-coated bubble is produced at the orifice and released into the aqueous solution. To control foam properties, the effect of some surfactant additives is investigated. Silicone oil is found to have a strong foaming action with kerosene-based solvents. The volume of foam produced was increased substantially without affecting extraction or stripping of copper (with LIX reagents) or zinc (with D2EHPA).