Selective and rapid gold separation from practical e-waste by phosphorus-based ionic liquids

Abstract

With environmental problems and a shortage of resources, it is urgent to recover noble metal from e-waste. Herein, a series of phosphorus-based ILs containing triphenylphosphine groups and alkyl chains of different lengths have been designed for selective extraction of gold from PCBs, further exploring the correlation between ILs structure and their performance. These ILs exhibited fast extraction kinetics, achieving extraction equilibrium within 1 min. Notably, the IL with the shortest carbon chain length emerged as the standout performer, boasting the highest electrostatic potential value, which directly correlates with its superior extraction efficiency, reaching up to 550 mg/g. Most impressively, even under the stringent conditions of high HCl concentration, they have demonstrated remarkable resilience. The extraction mechanism has been elucidated to be anion exchange by spectral characterization and electrostatic potential analysis. The exceptional extraction capabilities, complemented by its commendable reusability, firmly establish its potential for practical application in highly acidic solution.