Ultrahigh Capacity and Rapid Selective Recycling of Gold Ions by Organic Intercalated and Exfoliated Few-Layer Ti3C2Tx Nanosheets

For the sustainable development of the ecological environment in gold recycling, it is urgently desired to develop a more efficient and highly selective process for gold ions from e waste or mineral lixivium. As a kind of emerging two-dimensional nanomaterials, Ti3C2Tx has emerged as a rapidly developing novel water treatment material. Herein, the preparation of few-layer Ti3C2Tx nanosheets and their performance for recycling of gold ions were studied. Notably, it exhibits an impressive capacity of 2973.57 mg/g at room temperature, almost 124 times that of commercially available activated carbon (24 mg/g), and an exciting selectivity for Au(III) in the presence of competing ions due to perfectly weak reduction caused by the removal of the Al layer. The Langmuir isotherm and pseudo-second-order kinetic model can accurately depict the rapid adsorption process. Additionally, it can be regenerated effectively by thiourea and exhibits excellent reutilization. A critical mechanism involves an adsorptive-reduction pathway between Au(III) and active Ti sites. Excellent performance in real lixiviums from e-waste and gold-bearing sludge is also exhibited, demonstrating great potential for Au(III) recycling. It may be a sustainable direction for the capture and separation of Au(III) and also lays the foundation for the interface control of Ti3C2Tx and Au NPs as a catalyst and other functional materials.