Efficient and selective extraction of gold from acidic leaching solutions using novel guanidinium ionic liquid.

• A novel guanidine salt ionic liquid ([DIETMG][NTf 2 ]) was synthesized, and its gold extraction capacity was 295.7 mg·g-1. • The system avoids using organic diluents. • The extraction mechanism is anion exchange mechanism. • The extraction process is spontaneous, accompanied by heat release and entropy reduction. • The system exhibited satisfactory selectivity and reusability. As gold is a non-renewable resource, it holds both economic and environmental importance to enhance the recycling of precious metal waste from secondary resources. Herein, a guanidine salt ionic liquid ([DIETMG][NTf 2 ]) with low water solubility and viscosity was synthesized by molecular design of guanidine salt ionic liquid with good biocompatibility and biodegradability, and a solvent-free system of [DIETMG][NTf 2 ]-water was constructed to extract Au(Ⅲ). The findings reveal that the extraction efficiency of Au(Ⅲ) can reach 97.57 % under optimal extraction conditions. Further thermodynamic and kinetic studies revealed that the reaction process is spontaneous and exothermic, with the extraction rate being primarily controlled by interfacial chemical reactions. The system demonstrates remarkable selectivity for Au(Ⅲ) in solutions containing a mix of various metal ions. Finally, ascorbic acid (Vc) was employed as a stripping agent to obtain gold at room temperature. After 8 cycles, [DIETMG][NTf 2 ] still achieved a 90% extraction efficiency. This study provides a new idea and method for recovery of gold from secondary resources. [ABSTRACT FROM AUTHOR]