Introduction

Efficient and selective extraction of Pd (II) from multi-metallic aqueous solutions, deriving from Hi-Tech waste leaching or wastewater from industrial processes. The extraction works through Cloud Point Extraction based on the action of a “green” ligand dissolved in a small amount of non-ionic surfactant, and subsequent recovery of Pd in the form of a metal complex from the surfactant phase.

Technical features

This patent provides a sustainable approach to the selective palladium extraction stage from dilute and complex solutions, such as industrial wastewaters or leachates deriving from the non-selective chemical treatment of solid materials containing metals (mineral or secondary raw materials e.g. Hi-Tech waste).
As an alternative to the solvent extraction methods, which use large amounts of volatile organic solvents and require numerous steps, in this invention palladium (II) can be selectively and quantitatively extracted putting in contact the multi-metal solution with a small amount of a non-ionic surfactant containing the selected ligand, then raising the temperature to exceed the cloud point. The Pd complex obtained from the interaction with the ligand is concentrated in the surfactant phase and easily recovered from it.

Possible Applications

• Recovery of palladium from multi-metallic wastewater;
• Selective recycling of the palladium from leaching solutions derived from secondary raw materials (exhausted car catalysts or WEEE);
• Concentration of the precious element from dilute solutions.

Advantages

• Selective Pd extraction from a complex aqueous system;
• Low environmental impact;
• Low cost;
• It avoids the use of large quantities of volatile organic solvents;
• Small amounts of surfactant;
• High efficiency that limits the n. of extraction stages.