Green and efficient gold recovery from e‐waste: Mechanistic insights into urea‐based deep eutectic solvents

Abstract This study presents a green and efficient method for recovering gold from electronic waste using a novel urea‐based DES system. Among three newly developed DESs, the [TOMAC][DBU] formulation demonstrates exceptional Au(III) extraction performance from hydrochloric acid media, achieving over 97% extraction efficiency and a remarkable capacity of 387 mg/g, with high selectivity and excellent recyclability. Mechanistic investigations revealed that the high extraction efficiency originates from a coordination substitution reaction between the amide groups of the DES and [AuCl₄] − , leading to the formation of stable complexes. Thermodynamic analysis indicated that the extraction is a spontaneous exothermic process, and kinetics followed a pseudo‐second‐order model. The optimal extraction system achieved 87% gold recovery from a real e‐waste aqua regia leachate. These findings highlight the potential of the proposed DES as a sustainable and effective alternative for gold recovery, contributing to the advancement of green technologies for precious metal recycling from secondary resources.